Behavioural ecology Flashcards
Clown fish sex change
breeding pair plus sub male
female dies, big male become female (females bigger than males)
sub male can’t do anything before this situation because lives in their anemone (reproduction limited by ecology)
link between size and fecundity
Blue-headed Wrasse sex change
Thallassoma bifasciatum
females have lower max RS but will always have some
good males have high RS, bad none
better to bide time as a female until big enough to compete as male
Angler fish mating
extreme ecology leads to extreme mating system
males attach to females and merge bloodstream, some male organs dissolve
females can have multiple
Cory mating (Callichthyidae- armoured catfish)
‘classic T position’
female drinks sperm which pass through digestive tract and deposited into pouch with eggs
male sperm have to survive digestive tract therefore costly for males, they run out of sperm before females run out of eggs
Seahorse mating system
males invest more in young care therefore males are choosier
Macaque mate choice
Young males will try to look after young of others to show good father
=competitive altruism
Baboon offspring survival
Increased for females with stronger social relationships (maybe other females less aggressive?)
Vampire bat reciprocal altruism
Females regurgitate blood for others who haven’t fed in a while (have v high metabolism need lots of food)
Later reciprocation
Hermaphroditic flatworm
Pseudoceros bifurcus
fight with penises over which one assumes male role in mating
each wants to be male because less effort
winner will puncture body cavity of the other and will be male, can mate again more quickly
the loser has to recover puncture before remating
Pinniped mating systems
Species which haul out on beaches will have greater density of mating individuals, increased chance for males to command big harems in comparison to species which haul out of ice (can go anywhere), therefore more likely monogamous
Testing female choice in long-tailed widowbird
Andersson, 1982
Male birds have ~1m long tails
Modified male tails: unmanipulated, cut and add longer, cut and stick back on, shorten
Longest had most nests, shortened had reduced
Sage warbler songs
“acoustic peacock’s tail”
males with most complex song mate earlier in season
females in cages react more strongly to more complex playbacks
Vogelkop Bowerbird male attraction
males create weaved twig huts and decorate with flowers, fruit, dung etc
remove decorations, don’t attract as many females
signal of genetic quality: sensory and motor capabilities. Can collect and defend effectively
Peacock eyespot experiment
Petrie, 1994
Semi-wild population in Wipsnade
8 males with varying number and area of eyespots, allocate ~40 females at random for mating
eggs raised by chickens
males with greater mean eyespot area had more surviving offspring two years on
Gray tree frog experiment
Hyla versicolor
Welch et al., 1998
females prefer males with long calls
experimentally fertilise female eggs with sperm from males with different call lengths
offspring sired by long-calling males produced tadpoles 2x as fit as those with short calls
Dung fly study
Geoff Parker (1970)
females often mate with several males
females store sperm in spermathecae
sperm competition (sexual selection continues post mating)
explains mate guarding, frequent copulating behaviour, mate plugs and testis size
Sperm competition in primates
Chimpanzees- polygynandrous
multiple males, competition for mating when female into oestrus (sexual swellings)
females mate with many males
testes nearly as big as brains
Gorillas- polygynous
single male controls group and has sole paternity
Drosophila melanogaster sexual conflict
male accessory proteins (Acps) with sperm
harmful to females, cause increased egg laying rate and decreased ability to remate
females mating with genetically engineered males lacking Acps or males with external genitalia ablated survive ~1 week longer
Selection experiments, intense sexual selection line and none (by enforced monogamy) line
Remove sexual selection, females survive longer- males don’t use as many Acps and don’t mate as frequently
Mate females from monogamous line with males from sexually selected line, females do less well than those in the line, have evolved decreased defences
Antagonistic coevolution
Water strider sexual conflict
Gerris spp.
males grasp females to mate
mating multiple times costly to females because decreases mobility so decreases feeding success and increases predation
females get enough sperm in one mating to last life
but males compete
males adapt to increase grasping abilities- armament on abdomen
females have increased spine length in these pops to resist mating
diff pops have different levels of armament (differences in benefits and costs?), and corresponding spine length (coevo)
Red-winged blackbird EPCs
20% of a males RS through EPCs
Effect of EPCs on offspring success in Blue tits and coal tits
Blue tits- offspring from EPCs more successful- but small sample size
coal tits- 3000 chicks form 400 broods (larger)- no difference found
But could be due to seasonal effects- females seek more EPCs later in season so maybe offspring of these at advantage when resources scarce
Antechinus polyandry
semelparous marsupial
experiment:
monandrous females- mate with same male 3x
polyandrous female- mate once with 3 males
polyandrous female had better RS
certain monogamous did as well (those with high quality males)
polyandry therefore increases chances of good genetic sire
Collard flycatcher EPC experiment
remove female from nestbox for an hour during fertile period
male thinks EPCs and decreases paternal care
therefore is tradeoff for females
Effect of attractive mate on offspring fitness in crickets
Less attractive males produce more fit daughters
More attractive males produce more fit sons
Do females need to temper mate choice to ensure all offspring fit?
Bias sex ratio in collard flycatchers
Females heterogametic - WZ
Can potentially control sex ratios of offspring
Females mated to males with larger forehead patches (more attractive) have ratio biases towards sons
Experimentally increase patch size- female has more sons
Dungfly paternity (& insects generally)
Double mating experiments
2nd male gets 80% parentage (displaces first males sperm from storage sacs)
therefore mate guarding
Female sperm choice in field crickets
Used genetic markers to look at sperm storage when females doubly mated with a different combos of nonsib and sib
when both males sib- inbreeding depression
when at least one nonsib, female bias in favour of choosing sperm of nonsib (less likely to store sib sperm)
Stalk eyed fly runaway selection
females prefer males with longer eyespan
selection lines in lab for 13 generations- select only for eyespan
female preference coevolved with it
clear genetic correlation
Chase away selection in ducks
penis driven by lymphatic system, inflates inside of females and corkscrew shaped
female reproductive tract also coiled
spirals are in different direction to make it harder to males to inseminate
increasing phallus length drives greater number of female coils and an increased number of pouches(dead ends) in reproductive tract
Brennan et al., 2007
Swordtail characin cost of resisting male charms
Kolm et al., 2012
males have long extensions to operculum with blob on the end to attract females
blob shape reflects food preferences in females
eg. forest pond, ant shaped
eg. open pond, beetle shapes
higher proportion of ants in diet, greater shape similarity of ants and lure
females fed ants in lab direct more bites at male ant shaped lures than those fed other things
potentially too costly for females to resist lures because could compromise foraging success
Chase away selection in swordtail fish
female preference for sword tails stronger in species that lack swords
suggests that males evolved swords to exploit pre-existing female preference
but as they evolved, female preference decreased
Natterjack toad inferior male tactic
loudest shouts best at attracting females
small males can’t shout loud enough
=satellites, sit near calling male and try and get female when she arrives
usually get ~50% of matings
therefore, should decide to parasitise neighbour if calling 2x as loud as you
90% of decisions as predicted by this
Dung beetle male tactics
Onthophagus
large males with horns
small males look like females
which phenotype depends flexible developmental programme- depends on size and how much food as larva
horned males guard nests with female inside
small males dig into nest in attempt to sneak matings
switch point at ~5mm pronotum width
laboratory experiments show that threshold size for switch can be changed via selection
select smaller sized, decrease threshold and vice versa
European earwig male strategies and ecological conditions
2 male morphs- large forceps (better at fighting) and small forceps
UK mainland, almost all small forceps
UK islands, greater proportions with big forceps
allometric sigmoidal relationship-switch at a certain body size
island switch size is lower due to higher population density- greater payoff for fighting even at smaller size
Alternative strategies in scale eating cichlids
2 strategies: mouth twisted left, or twisted right
2 morphs present in 7 different species
ESS= 50:50 proportion, because each host has two sides
Human handedness strategies
10-13% population left handed
left-handed, very slightly lower life expectancy
left handed people have slight advantage in fights because rarer opponent harder to defend against
eg. higher proportion of boxing champions left handed than predicted by chance
Frequency dependent selection in figwasps
Fighting males with big jaws
dispersing males with wings
If all males fighters, good to be disperser because could mate with all females that emerge from fig that didn’t include fighter wasp
& vice versa
3 genetic strategies in male Ruffs
Philomachus pugnax
dark ruffs- territorial, attract females
white ruffs- sneak matings at edges of others’ territories
female mimics (only recently discovered)
Don’t know equilibrium between because disperse, can’t tell mating success
3 genetic strategies in side-blotched lizards
males:
orange throats- guard many females
yellow throats- sneaks, look like females
blue throats- guard one female
oranges to best when high blue
yellow do best when high orange
blue do best when high yellow
no equilibrium in wild, cycle between differing proportions
can’t change tactics in this eg. because morphological specialisations
Golden eye ducks female tactics/ strategy
nest in woodpecker holes in trees, chicks jump out when hatch
some females parasitise nest and lay eggs in someone else’s
experimental tracking of chicks- can tell whose eggs are whose because characteristic shape
Tag chick feet just prior to hatching to track
Reproductive success tracking suggests that represents strategy not a tactic, because equilibrium value of 17% of eggs are parasitic (no sig. diff. from 20%, as predicted by equilibrium modelling)
But females don’t stick to same role throughout life- there may be a genetic propensity for one over another- does it depend on other individuals in pop?
Potentially LRS of parasite better- don’t have to care or guard box
Dunnock mating system
Prunella modularis
have different mating systems:
Polygyny, female RS= 3.8 per season, male= 7.6
Monogamy, female=5.0, male=5.0
Polyandry, female= 6.8, alpha male= 4.1, beta male= 2.7
Polyandry best for females, will solicit matings with any new males they encounter
Monogamy better for females than polygyny, fights between females for full territory
Polygyny best for males, try to stop females fighting, and in polyandry, alpha consistently trying to chase off beta in polyandry
Often see polyandry in dense vegetation
Polyandry in Dunnocks
females wants equal chances of paternity from her chicks- 50:50, increases amount of paternal care chicks receive
Normally, female tries to increase mating with beta to reach ratio
If alpha male experimentally removed for period of time, will mate more with him when he’s returned
Males can’t distinguish own chicks, therefore use mating share as indirect cue of paternity
If beta mates, he will care
Even if experimentally reduced brood to 1
No paternity markers- chicks and mothers don’t want them, because they would reduce amount of care given (genetic suppression by both chicks and mothers?)
Cooperative brood care in monogamous birds
Houston-Davies model- “sealed bids”- evo game where efforts fixed and optimal investment of each carer reached over evo time
Individual’s best effort in reaction to partners effort decreases with shallow gradient and partner puts in more effort
4 different outcomes:
ESS- stable equilibrium between two optimal
ESS- male sole carer
ESS- female sole carer
Unstable - overcompensation of one, depending on starting effort
eg. starlings
together, male provides 12 feeds per hour, female 13
weigh down female, she provides only 7, male provides 14
weigh down male, he provides 7, female provides 15
Incomplete compensation- are they responding to partner’s reduced effort or indirectly via increase in chick begging?
Great Tits feeding chicks (cooperative brood care)
broadcast extra begging calls from speaker at nest box
ensuring that playback didn’t affect actual chick begging
increased calls = increased parental effort
playback to one of the two, ensuring not heard by other partner, both increase effort (more feeds per hour)
both chick begging, and what other partner is doing affects care
Superb fairy wren EPCs
males have iridescent feathers
76% young sired by EPCs
social monogamy, with previous offspring as helpers
Extra males bring yellow petals to female when in fertile period
Females go to territories of other males in early morning to copulate
5% of the males in a pop get 50% of matings
1 “super stud” has sired 450 out of 1800 chicks genetically profiled
females with many helpers- more EPCs, they will care for young even if male detects
Tasmanian native hen altruism
Tribonyx mortierii
Dominant male allows subordinate bother to copulate- more offspring can be raised (9.6 compared to 6.6 with a pair) with three parents helping
Whereas is subordinate alone LRS = 0
Because brothers, r=1/5, greater benefit to alpha male to keep brother because larger genetic profit from altruism than selfishness
Fraternal polyandry in humans in Ladak, Tibet
Can raise 5.2 children with polyandry compared to 3.75 with monogamy
Hamilton’s rule, dominant brother should share wife if
3/4 N2 > N1
Here 3.9 > 3.75 BUT very close
Under harsh conditions, may pay to have younger brother around, help increase farming productivity, enables more children, might offset paternity loss
Is female in control- for her advantageous as long as N2>N1
Importance of culture eg. Buddhists permit polyandry, but Hindus and Muslims don’t
Florida Scrub Jay kin selection
Young stay at home and help parents raise future broods
Seychelles warbler kin selection
Brood sizes v small (1 or 2)
Live only on Cousin Island
Pair of breeders raise 0.8 young to dependence each year, with a helper, 1.2
Stay because full habitat on island (ecological constraint) and indirect fitness gain
Translocation of birds to nearby Aride Island
within weeks, birds breed and pops expand, no helping
As habitat begins to fill up, start to have helpers again
DNA profiles show that 40% chicks are sired by EPCs
and female helpers lay some eggs
female helpers only care if their mother is present - she produces 85% of the chicks in a nest, therefore if she is present, helpers probably related to chicks (0.85x0.85=0.72)
But only 60% of chicks are produced by primary male, so if just he is present, chances of being related to chicks is 0.6x0.6=0.36
Long tailed tit kin recognition
Live in clans of 30 plus- breeding parents plus their sons and immigrant wives
at a point in the season, split into pairs to breed
magpie predators can destroy nests, if no time to rebuild, will go to help other nearby pairs (immigrant females won’t help though, because no kin)
16/17 choices, sons chose close kin to help over unrelated individuals
Recognise by signature calls of family (learnt from parents/carers)
broadcast churr calls, approach kin calls, and reply aggressively to non-kin
Ruby spot damselfly eavesdropping
Hetaerina Americana
Grether & Grey (1996)
male bright red spot at base of wing=sexual signal
But makes easier for prey to detect and avoid it (conspicuous)
Catch and manipulate females, though with red spots added had lower relative gain rate, even when controlled for age and size
Grass anole head bobbing displays
Fleishman, 1992
Anolis auratus
territorial males defend with head bobbing display, bright dulap pulses in and out
visually striking and attracts other males’ attentions
to maximise detectability, bob at high frequency different to that of background tree/leaf movement
Vine snake cryptic movement patters
Mimics background movement eg. branch in wind, similar f to background, harder for prey to detect
Narrow mouthed toads character displacement
2 species in different Southern US states
1 zone found together
mate attraction by calling
G. olivacea higher f than G. caroliensis
in sympatric overlap zone, diff in f exaggerated to minimise confusion, G. caroliensis lowers call f
Antbird song character displacement
Neotropical suboscines (innate, not complex songs) Sympatric species tend to have greater character displacement in song that allopatric species selection against inappropriate mating
Antithesis principle in dogs
Different behaviours are as maximally distinct as possible- hostile vs affectionate, change in tail/ears/back/face etc, greatest contrast
North American Wren song stereotypy
Most species repeat the same song multiple times
Three species (Short and long-billed marsh wren and rock wren) don’t repeat consistently, switch rapidly between song types, larger repertoires
These three live in habitats where there aren’t many other bird species and not much noise- where species recognition poses few problems
Redundancy in Jackson’s widowbird mating signals
Long tail, jumping display, courtship bower
Anole head bobbing alerting components
Spontaneous assertion display grabs attention of receiver with high amplitude and frequency movements (little information, no pattern), before moving onto informative display
Ord & Stamps (2008)
robot programmed to have:
-no display
-alert component and typical display or
-alert component and novel display
recorded receiver responses:
-in bright light and at close distance, no difference in time it takes for robot to get attention
-in dim light, takes longer when there was no alert
Plus, lizards in dimmer conditions and environments with more background noise, tend to increase rate of alert components
Warbler plumage and habitat
8 species in forests of Kashmir
small and green
vary in amounts of ornamentation (bright plumage patches) across species
patches play role in male individual territory defence
high patch size and number means larger territory size
(number of patches and the total reflectance at the feather tip is lower in higher light areas, when controlling for phylogenetic effects)
Colour patterns in guppies depending on environment
Male colour patches have different levels of conspicuousness in different levels of light to predators and other guppies
eg. prawns don’t detect orange well, therefore guppies often orange when prawns around, but less orange if fish is main predator
Nestling mouth colours
Davies & Kilner , 1998
gape colour in passerine chicks varies with light at nest
(red in reed buntings, yellow in robins)
Darker nest= wider mouth flanges that are whiter and less densely coloured relative to mouth, but mouth didn’t change colour (increasing contrast, more detectable)
Golden-collared mannequin background modification
males golden colour with black crown and back, display to olive females
creates display court, clears away leaves, helps show off plumage by increasing contrast with forest floor
Uy & Endler, 2004, colour and brightness contrast of golden patches greater against cleared court than adjacent leaf litter
Asian whistling thrushes UV signals
look deep blue-black but reflect UV strongly, therefore brightly coloured to conspecifics (mammals can’t see)
evolved because of habitat- high altitude forested streams and gorges that receive high levels of skylight rich in UV wavelengths, but nest and forage on ground so pays to be cryptic to mammalian predators
Honey bee waggle dance
female workers recruit others to food resource
figure of 8 and waggles abdomen in centre on vertical wax plane
angle of centre part of dance to vertical = angle between sun and direction of food source from hide
duration and intensity of waggle informs on distance and resource value
fully cooperative behaviour
Bolas spider chemical lure
pheromonal lure that mimics female sex attractant of moths, spiders catch and eat male moths that arrive
Motion sensitivity in jumping spider
Maevia indemens
2 male morphs: dark bodied and striped
have different courtship and display at different differences
dark morphs raises itself and front legs up
striped flattens self
females don’t seem to prefer either morph, approach first male to move
Fiddler crab sensory biases
Uca beebei (Christy, 1988) in a number of species, males build vertical pillar next to burrow exploits bias for crabs to detect things that break line of horizon(hide from predators in) eyes have narrow vertical pseudopupils where ommatidia densely packed = superior visual activity in vertical plane
experimentally, vertical rectangular shapes more consistently elicit spontaneous approach than horizontal rectangles of equal area
Christy et al., 2003
arena with male burrows, some pillars are removed
female approaches pillars in mating context
females also run towards pillars when scared by predator (sensory bias evolved in non mating context)
this bias also seen in predator situation for species that don’t use pillars (mating preference before trait evolution)
Aversion to aposematic colours in domestic chicks
Rowe et al., 1996
offered rtificially coloured food, one colour made distasteful
when pyrazine odour present, even at beginning of experiment, do better when learning to avoid brightly coloured than duller coloured
biased against bright colours even when not distasteful
Motion sensitivity in water mite
Neumani papillator
Proctor, 1991&92
‘courtship trembling’
ambush predators, grab prey items when detect water vibrations
males approach waiting females and vibrate water so she grabs him and sees potential mate
females deprived of food more likely to orient to and clutch vibrating males
nuptial gifts in nursery web spider
Stalhandske, 2002
Pisaura mirabilis
male provides silk wrapped prey item to mate
gift mimic female egg sac, which she has propensity to protect and carry around
males take advantage of this instinct?
Experiment:
paint courtship gifts to be as white as egg sacs (normally darker than them), latency of female to grab it reduced the brighter it gets
Túngara frog calls
Engystomops pustulosus
Ryan & Rand, 1993
calls have chucks and whines
individual males have own calls
different related species have different versions of call- all have basic ‘whine’ with specific additions
splice together different call elements of different species’ calls
females have preference for different elements
different species take advantage of ancestral female preference (perhaps one broad ranging bias?)
Crickets pre-existing preference for nuptial gifts
provisioning of food gift eg. spermatothylax (elaboration of spermatophore that contains sperm), eating spermatothylax by female increases time the ampulla is attached to her and transferring sperm
therefore bigger gift = more sperm
suggested that preference for gifts evolved in common ancestor predating evo of gift giving– not all species crickets have gifts but some appear to have preference
experiment:
artificially supply spermatophylax for specis who don’t normally have
when present, spend more time eating and more time before she removes sperm ampulla, and less sperm left it in after
Pre-existing biases in swordtail fish
Basolo 1990, 1995
investigating female preference for sword on males in related fish
female choose males with longer tails in green swordtail
attach sword to southern platyfish (closely related but no tails), female preferred
therefore preference must have evolved first in common ancestor
but new molecular data suggest with revised phylogeny that either evolved together and tail first (Mayer et al., 1994)
Therefore unsure
Mexican house finches honest colouration
Mill et al., 2002
males have red plumage, determined by carotenoids and therefore indicating information about foraging success and nutritional condition (most animals cannot make carotenoids)
males in population vary in colour intensity, poor quality males have less colour
mate choice experiment, females prefer most intense colours- conveys honest information, gives fitness benefits to female
brighter red males moult earlier and grow feather more quickly, and have higher carotenoid concentration in gut
Thompson’s Gazelle stotting
FitzGibbon & Fanshawe, 1988
vertical jumping as a pursuit deterrent
predator approach => stotting rather than running straight away
predators choose gazelle with worst stot
more vigorous stotting = better condition and harder to run down (reliable info about stamina and endurance)
Chick begging as honest signal
Magpie- Pica pica
Redondo & Castro, 1992
high pitched calling and brightly coloured gape in some birds
amount of begging in magpie = honest signal of nutritional need
greater time since fed to satiation, greater gape area and rate of calling (higher to older chicks)
parental visit and feeding rates both increase when more chicks added or playback of more chicks added
honest because cost of begging
But McCarty, 1996 “the energetic cost of begging is surprisingly low”
But measured energetic costs and not costs to fitness- need to actually know how begging costs affect growth
Cost of wolf spider drumming
Mappes et al, 1996
Production cost
attract females by drumming abdomen on ground (tiring)
manipulate intensity with which males drum by exposing them to many for few females
encourage to drum more = lose weight more quickly and lower fraction survive, therefore clear fitness cost
males of low weight and low natural drumming intensity don’t survive long in high drumming treatment
Cost of swallow tail streams
Hirundo rustica
Maintenance cost
male streamers for mate choice
but aerodynamic cost
measured performance in a flight maze after tail manipulation
tail has costs- typical streamers exceed aerodynamically optimal length by approx. 12mm
Spotted bowerbird bower destruction
Chlamydera maculata
Madden (2002)
corridor of twigs with court infront
females prefer solanum berries, therefore males collect many
manipulate by adding berries = elicits more aggressive attacks and stealing from other males (can’t maintain bower with too many berries)
when offered free supply of berries, number of berries they had at start positively correlated with how many they take
appears to assess social standing in relation to neighbours and modulates display accordingly
Black kite nests
Sergio et al., (2011)
territorial
decorate nests w eg. plastic waste
old and young individuals have few nest ornaments
middle aged have the most and more likely to take free offered ornaments
nest decoration correlates with trespassing on territory by ‘floaters’
manipulate nest by adding ornaments, individuals in prime of life can defend off increased attack rate but others cant deal with increased aggression
Pheromones in tiger moths
Utetheisa ornatrix
Dussord et al., 1991
male sex attractants
during mating, male transfers chemicals n seminal fluid (toxic alkaloids) too female, who incorporates them into eggs (protects) - female wants males that provide lots of chemicals
pheromone similar chemical composition to described chemical- therefore = informative of quality of how much alkaloid male can provide
selection for reliability
(males also want to provide alkaloids to offspring- therefore amount released relative to overall amount available)
Variation in passerine chick begging volume
Strategic
Increased extra pair paternity -> in nest with half sibs
selected to be more selfish and misrepresent hunger
louder begging for food
feeding and sexual response in Goodeine fish
Garcia & Ramirez, 2005
terminal yellow band on male tails, looks like worm when moved
elicits feeding response in females (exploitation of feeding bias in mating context)
more elaborate band decreases feeding response but sexual response remains (because costly and therefore honest signal - males and females with yellow bands suffered more damage confined to area of band when kept in outdoor ponds)
Therefore initial evolution was exploitative but has become honest
Cuckoo low frequency exploitation
eg. in reed warbler nest
as cuckoo grows, gape increases, but doesn’t grow more than overall gape size of al other chicks in nest
therefore compensated by begging more intensely for a given level of hunger (Kilner et al., 1999)- have no genetic interest in future RS of adoptive parents
Parents attend to begging calls- cuckoo parasitisation sufficiently rare that still pays to attend chick begging
Mantis shrimp deception
Adams & Caldwell (1990)
continues to display threat displays to repel intruders entering burrow, even when just moulted and unable to fight effectively
intruders do best to respect signal, because in most cases represents real threat
Cleaner wrasse
Stations where larger fish/ turtles come to have parasites cleaned from gills
have local client fish with small territories and free ranging fish which have multiple options of cleaning stations they could visit
cleaners would prefer to eat the mucus and scales of clients (Grutter and Bshary, 2003)
but if take a bite= lose a client, bad for rest of cleaner group
more likely to cheat and take a bite out of local fish, because they have no choice of cleaning station
Cleaners often work in pairs, number of mechanisms to reduce cheating eg. partner switching, punishment plus threat of reciprocity by client
2 different, unfixed strategies of cleaners:
- low interest in small clients and rarely cheat larger clients
- small minority cheat large non-predatory clients with 6x higher frequency (Bshary, 2002)
cheaters give tactile stimulation with their fins, lowers basal and acute cortisol levels in clients- use to build new relationships with clients, to reconcile after cheating and as a pre-conflict management strategy with predators
Observation of a cleaning interaction without conflict attracts new larger clients, so tactile stimulation of smaller fish can falsely entice larger that are then bitten to obtain mucus
Injection of fish with cortisol or blocking of their glucocorticoid receptors increases this ‘cheater’ behaviour (Soares et al., 2014)
Vervet monkey alarm calls
semantic communication in nonhuman animals
acoustically different alarm calls to different predators
each call causes different, seemingly adaptive responses
Monkeys on the ground respond to leopard alarms by running into trees, to eagle alarms by looking up, and to snake alarms by looking down
Seyfarth et al., 1980
played recordings of alarm calls in absence of predators and observed responses
alarm length, amplitude and alarmist’s age/sex class had little effect on response quality
But, calls similar sounding in aggressive context
eg. overlap between female calls given to snakes, eagles and during aggression
eg. male barks in leopard and aggressive contexts
Price et al., 2015
semantic properties of alarm calls bear little resemblance to human words, but acoustic variation, possibly with additional contextual information, allows listeners to select appropriate responses
Complex communication in orcas
field observations of killer whales have documented the existence of group-differentiated vocal dialects that are often referred to as traditions or cultures and are hypothesized to be acquired non-genetically
Abramson et al., 2018
subjects were able to make recognizable copies of all familiar and novel conspecific and human sounds tested and did so relatively quickly
suggests vocal variants observed in natural populations of this species can be socially learned by imitation
Mammalian large brain size evolution
All three ‘peaks’ of large brain size evolution in mammals (odontocetes (esp. dolphins and sperm whales), humans and elephants) shared a common selective environment: extreme mutual dependence based on external threats from predators or conspecific groups
In this context, social competition, and consequently selection for greater cognitive abilities and large brain size, was intense.
Tandem running in rock ants
Form of teaching (fulfils all requirements)
Tandem leaders know food location, tandem followers naïve
leader only continued the tandem run when frequently tapped on her legs and abdomen by followers antenna
The tandem leader therefore modifies its behaviour in the presence of the follower
Imposes cost on leader because can move 4 times faster without follower- tandems slowed by frequent pauses where follower loops round, probably in search of landmarks (speed of run higher in presence of conspicuous landmarks than when absent)
Followers found food more quickly when tandem running than when foraging alone
Bidirectional feedback between the leader and follower is evident from their patterns of acceleration and deceleration as a function of the strength of the stimuli they present to one another- when gap between them too large, leader slows and follower speeds up
Lessons learned by followers transferred when they become leaders for others- therefore propagates time-saving knowledge between individuals
Bidirectional feedback distinguishes it from broadcasting in other ant species (eg. pheromone trails)- effective in big groups
teaching works better in smaller societies, where info is valuable and easily lost
(big brain is not a prerequisite of teaching)
Great Tit care depending on clutch size
David Lack- add or remove eggs
Parents provide less food per offspring to enlarged broods- reduces offspring mass and survival (survival to 1 year reduced in enlarged clutches) - Smith et al., 1989
Parents act at optimal rate of feeding in each treatment
Burying beetle parental care manipulation
Larvae raised either in absence or presence of parents
Better off when parents present (Eggert et al., 1998)
Comparison between biparental care and sum of male and female uniparental care treatments- offspring grew larger and were more likely to survive to adulthood in biparental (first empirical evidence of synergistic effects of biparental cooperation on offspring fitness) - Pilakouta et al., 2018
Effects of noise pollution on Spiny Chromis offspring survival
Nedelec et al., 2017
repeated motorboat-noise playback compared to ambient noise increased defensive acts and reduced feeding and offspring interaction of brood-guarding males
noise didn’t affect offspring growth, but reduced the likelihood of survival
(6/19 nests with motorboat noise suffered complete nest mortality, whilst all with ambient treatment survived)
Strawberry poison dart frog parental care
Females deposit tadpoles in separate pools eg. bromeliads
Lay unfertilised trophic eggs for developing tadpoles to feed on- survive better and growth larger with more trophic eggs provided (Dugas et al., 2016)
Parental care had costs to both sexes, either through reduced productivity of reduced parental longevity
Red deer costs of reproduction
Isle of Rhum
Females that successfully reproduced one year experienced survival and fecundity costs in the next breeding season- but results were partially dependent on population size
Weaver bird costs of parental care
Individuals whose clutches had been experimentally removed had reduced oxidative stress and increased weight compared to breeding birds
But these costs of reproduction only accrued by individuals breeding in groups with few or no helpers
Wandering Albatross terminal investment
Froy et al., 2013
Long-term data set to relate measures of parental care to reproductive success (offspring survival and quality, parental age) - care for over half a year per chick
Generally improved their parental performance early in life likely due to increasing experience, but then showed decline in performance, likely due to senescence
Very last reproductive attempt, invested heavily and achieved high reproductive success
Senescence and terminal investment in rhesus macaques
Hoffman et al. (2010) examined relationships between maternal age and activity, mother and infant body condition, interbirth intervals, measures of behavioural investment in offspring, and offspring survival and fitness
older mothers had lower body mass indices and were less active, had longer interbirth intervals, and spent more time in contact with infants, but had infants of lower masses and survival rates- mostly consistent with senescence, but some results consistent with predictions from terminal investment hypothesis
Mantid sexual cannibalism
Praying mantid- female cannibalises male during mating
Brown & Barry (2016) - males and females fed differently radiolabelled crickets and allowed to mate- half pairs progressed to sexual cannibalism, other half stopped
Assessed relative allocation of both male-derived somatic materials and ejaculate materials into the eggs and soma of the female- male somatic investment does contribute to production of offspring
eggs and reproductive tissues of cannibalistic females contained significantly more male-derived amino acids than those of non-cannibalistic females, and there was an increase in the number of eggs produced subsequent to sexual cannibalism- therefore increases male material investment in offspring
In absence of cannibalism, males still 25% of their radiolabelled amino acids via the ejaculate
Terminal investment in frogs with infectious disease
gametogenesis in two endangered frog species susceptible to Bd fungal pathogen
Increased when infected
Corroboree frog - infected males have thicker germinal epithelium, and a larger proportion of spermatocytes
Whistling tree frog - infected males had more spermatic cell bundles in total, and a larger proportion of spermatozoa bundles and infected females ovaries and oviducts were larger in infected animals, and there were more cells present within the ovaries
because mounting immune response costly and can reduce investment in other life history traits eg. reproduction - terminal investment hypothesis predicts will increase reproductive effort when threatened by disease
However, if infected animals are increasing reproductive efforts and producing more offspring before succumbing to disease, it is possible that population-level selection for disease resistance will be minimized
American passerine parental investment
Species that live in harsher, northern habitats had lower annual survival and laid larger clutches than species in more benign southern habitats
Northern more willing to risk lives at benefit of offspring
Where residual reproductive value is low, parental investment into current reproduction should be high and vice versa
Cortez Damselfish parental care
males sole carers, females lay and desert
Males eat small clutches/eggs at earlier developmental stage - weigh up costs of caring for egg vs benefits
Females benefit from males caring, but males eat eggs they don’t sufficiently benefit from
Females avoid conflict by choosing males that already care for a clutch still at a v early stage
Scissortail sergeant parental care
Males sole carers
Will eat if doesn’t think caring will sufficiently benefit him
females appear to test whether a male will provide care by laying a few eggs and returning later to see whether eaten before providing with rest of eggs (Manica, 2010)
Genomic imprinting in mammals
Conflict between maternally and paternally inherited genes in the offspring (some genes, only maternal one expressed, others, only paternal)
Paternal genes favour taking increased resources from mother whilst maternal genes counteract them
eg. insulin-like growth factor IGF2 and its receptor IFG2r
IGF2 paternal, increases growth, IGF2r maternal, decreases reception of IGF2
Black-headed gulls manipulative androgen hypothesis
females deposit androgens in eggs which affects offspring begging behaviour and can manipulate males into providing more care
males responded more to testosterone mediated begging than females (Noguera et al., 2013)
manipulate testosterone in egg, increases begging 2.5x that of unmanipulated
Female enforced monogamy in burying beetles
Males can increase RS by attracting second mate when they encounter a large carcass
Females don’t gain from this, lowers her RS
When male attempts to attract another female by lifting abdomen and emitting pheromones (sterzeln behaviour), mate will knock him over to prevent and bite and bully him to stop future attempts (Eggert & Sakaluk, 1995)
Lion/Gorilla infanticide
Kill current offspring of a female to get females that are still caring for young to enter oestrus again
Less likely to see infanticide in seasonal breeders, females can’t resume reproduction
Coercion strategy to force partner’s parental investment away from current and towards future offspring
Paternity confusion viable counter strategy for females, reduced likelihood of infanticide (Lukas & Huchard, 2014)
Penduline tit manipulation
Each parent can increase RS by leaving mate to care and remate
Females lay an egg per day and copulates with chosen male each day
But timing of desertion crucial- if male leaves too early, mate may not finish clutch or mate with other males but if they wait too long, face female deserting (and then have to choose whether to care or desert)
If female leaves before completing clutch males more likely to desert as well, but too late more likely male deserts
Each tries to deceive other
eg. female covers eggs with nesting material, making male believe clutch at earlier stage and therefore confuse when he should leave
Cardinalfish filial cannabilism
Females increase apparent size of clutch at reduced cost by producing dummy eggs that don’t contain yolk and don’t hatch- but cheaper to produce while potentially deceiving males into investing into clutches they might otherwise eat
Patriarchal human societies that ensure paternity
Many religions incorporate rules to ensure paternity
eg. the Dogon of Mali traditionally expect women to sleep in special hut when menstruating, advertising their approach of fertile phase to whole community (esp husbands family)
Results in lower extra-marital paternity
Lake Tanganyika clown cichlids negotiations over care
Negotiate amount of mouth brooding- influenced by male’s state
males expend less investment when in worse condition
Can’t feed when brooding
Eggs exchanged from female to male once, when she signals for him to take over
But if starve male before, female cares more before he takes over (ignores her signals)
Other way round doesn’t happen- he chooses when to take brood
But, even when starved he still always cares for longer overall
Convict cichlid parental care
No bias for male or female to care more
larger fish more likely to desert because more attractive
Rhesus macaques parent offspring conflict
Offspring suckling prevents mothers conceiving
Both determine rate at which offspring gain access to nipples
as offspring get older, rate of milk feeds reduced from ~15 per hour at 4 months to less than 5 at 12 months
Result of decrease in offspring attempts and increase in mothers rejections (rises from 40 to 80%)
Gomendio et al., 1991
Expect to be in conflict over timing of weaning
But strongest determinant of the reduced rate due to reduced number of attempts- therefore maybe not at conflict? Actual fitness correlates of behavioural changes weren’t determined
Galapagos fur seal parent offspring conflict
Females wean offspring after two years of lactation
But some females give birth to pups in two consecutive years- suckle a yearling and newborn simultaneously
Older offspring often aggressive towards younger
Female aggressively interferes with elder’s attempts to subdue younger- sometimes causing actual injury to elder (Trillmich & Wolf, 2008)
Appears mothers actually use aggression towards yearlings to assess how they should optimally distribute investment (yearlings already survived a year so their interests should align more)- if yearlings persist despite aggression= sign of need is honest- in mother’s best interests to feed yearling at new-born’s expense
Actual conflict between mother and newborn
But also sibling conflict
Sex allocation in haplodiploid monogamous insects
Haplodiploid, monogamous, queens equally related to male and female reproductive offspring
But worker daughters more closely related to females (young queens) r=0.75 (brothers r=0.25)
Queen wants 1:1 ratio, workers want 3:1
Hymenopteran systems, queens lay eggs at 1:1 ratio, but actual sex ratios are closer to 3:1 - workers skew survival of eggs/larvae towards their best interests
But in polygamous, workers become equally related to brothers and half sisters (r=0.25)
Split sex ratios in social insects
Species where some colonies produce predominantly male reproductives and others mostly female
eg. wood ants- colonies tend to invest more into females when queen singly mated, into males when mating with multiple males
Queen lays ratio 1:1 but colony bias it one way or the other
Turtle egg parent offspring conflict
Janzen & Warner, 2009
Mother’s fitness (clutch hatching success) maximised at a lower individual egg mass than offspring fitness (individual hatching success) in two out of three species
Observed egg masses closer to mother’s optimum in these 2, suggesting that offspring have very little scope in influencing egg investment
Soay sheep parent offspring conflict
Life bearing animals balance offspring number and size
Offspring provisioned continually may have more power compared to in egg-laying species
Soay sheep- mothers benefit from giving birth to twins, which increases their LRS, but twin offspring have lower birth weight- reduces own survival and lifetime fitness (Wilson et al., 2005)
But have no data on fat content of mother’s milk, suckling frequency, maternal behavioural care - don’t have all evidence of parental investment
And no data how these affect parental future reproduction
Poecilid fish parent-offspring conflict
Placental, live bearing fish (matrotrophy)
most maternal investment after egg fertilised, embryos may be able to influence amount of investment they receive
2 populations that differ in offspring number vs offspring provisioning:
Moore Lake(ML)- more offspring than Wakulla Springs (WS)
In gestation phase, ML offspring gain less weight than WS- difference in offspring demand of resources
Offspring quality (weight) greatest for WS x WS
But female fecundity (offspring #) greatest for WS fathers x ML mothers (suggests offspring in control of offspring provisioning)
Coadaptation in canaries
mother’s influence offspring behaviour in nest by supplying different levels of hormones in the egg
Cross foster birds, increased fecundity cost to mothers the greater the mismatch between the begging level of their own brood and cross fostered brood
Suggests that in natural conditions, mother’s provisioning behaviour and offspring begging levels coadapted (would be difficult to detect conflict here)
Spadefoot toad sibling cannibalism
tadpoles can have different phenotypes- omnivores that feed predominantly on detritus or carnivores that feed on larger prey (incl. conspecifics)
Morphs often facultative- can switch between depending on diet- by supplying certain hormones a carnivorous diet induces and maintains morphological and behavioural changes
When large prey (and therefore the hormones) rare, revert to omnivorous
Ability of tadpoles to discriminate between kin and non kin varies with degree to which they are cannibalistic- individuals from more carnivorous species less likely to eat kin
(S. bombifrons obligate carnivores, S. multiplicate has the two morphs)
Sand tiger shark sibling cannibalism
First offspring to hatch in each uterus consumes all younger siblings and all unfertilised eggs in uterus- therefore only two end up surviving
Offspring seem not to differentiate between full and half sibs- devour all (Chapman et al., 2013)
Parasitoid insect offspring resource competition
Some species- gregarious larvae w multiple larvae on one host, others aggressive larvae- fight and kill each other until one remains
Comparative study showed that both species are capable of fighting, but gregarious larvae have reduced mobility during early larval stages- therefore if either species encounters another larva, 50% chance of survival- gregarious sp just don’t encounter each other
Increases number of eggs that become adults per host- but tend to be smaller
Siberian jay territory sibling rivalry
siblings fight over which gets to remain in natal territory
Philopatric birds have higher survival than those forced to disperse (Ekman et al., 2002)
Lake Tanganyika daffodil cichlid territory sibling rivalry
Individuals only gain considerable fitness once dominant breeders in their group
Dominance typically established via aggressive interactions among potential sibs
(Stiver et al., 2006)
Mascularisation of female mice in uteri
When flanked by male mice on either side
The testosterone diffusing from male embryos changes development of genetically female fetus towards more masculine traits
More aggressive, shorter lives, lower RS
Spotted Hyaena offspring begging
Submissive behaviour increased subordinate offspring’s suckling success
Subordinates did better as they got older- training effects?
Blue footed booby facultative brood reduction
Females typically lay 2 eggs- one hatches 4 days earlier than other
When food levels insufficient to sustain both chicks, one dies as direct or indirect consequence of aggression from senior chick
Aggression modulated by hunger of senior
Prevent from eating for a few days- tape throat- aggression increased as mass decreased
Suggests facultative changing of aggression, based on perceived costs of having sibling
Being aggressed doesn’t seem to affect juniors’ behaviour into adulthood
If conditions favourable and both survive- both show similar levels aggression as adults
Parasitoid wasp sibling discrimination
Individuals appear to target aggression towards less related sibs and unrelated conspecifics
C. floridinam- females lay up to 2 eggs into moth eggs- usually an unfertilised male egg and a fertilised female egg
Eggs then clonally reproduce up to over 1000 embryos each- create a polymorula
Some embryos from female egg develop into soldiers (elongate, huge mandibles)- roam caterpillar and kill other embryos
Soldiers sterile and die before caterpillar reached fifth instar, when other embryos consume host and disperse
Giron et al. (2004)- two artificial parasitism experiments:
resource limitation (and thus increased competition) doesn’t alter soldier behaviour - both situations soldiers avoided killing members of their own clone
But didn’t spare brothers, likely because relatedness = 0.25
But killed brothers less than unrelated
Otsuki et al., 2019
Mass killing of male clone larvae suggests intersexual conflict between male and female larvae, but mass killing is adaptive to all the killed males as well as the female soldiers that have conducted the killing because the killing increases their indirect fitness by promoting the reproduction of their clone sibs
Models indicate that optimal number of surviving males for both male and female larvae is very small but not zero - matches field data, optimal killing rate of approximately 94–98% of the males in a mixed brood
Maternal control of the sex ratio during oviposition, which is well known in other hymenopterans, is impossible in this polyembryonic wasp, therefore mass kill is necessary to maximize the fitness of the female killers and male victims, which can be seen as an analogy of programmed cell death in multicellular organisms
Banded mongoose cooperative begging
Overall amount of begging by a litter influences the amount of food each litter mate receives- more begging, more food
Thus overall supply not fixed, begging cooperative act
Individual increase of in begging can cause weight loss
Seychelles Warbler sibling rivalry
Most young raised alone, but sometimes two-chick broods (Bebbington et al., 2017)
Being raised with sibling has apparent costs of offspring- fed at lower rate and have lower body mass, negative effects on survival esp for subordinate
Birds that survive these adverse conditions had at least similar RS as adults- tendency for those w siblings to live and breed longer
Sibling rivalry affecting life histories
Mammals- how litter size and nipple number affect competition between siblings and influence growth patterns
In species with more offspring per nipple, prenatal growth higher in carnivores and insectivores
Postnatal growth showed reverse effect- females in full control of milk supply
Behavioural syndromes in 2 pops of sticklebacks
Bell et al., 2004
2 Californian populations of stickleback
examined the developmental stability of single behaviours (activity in an unfamiliar environment, aggressive behaviour and boldness under predation risk) and correlations between these behaviours
Single behaviours unstable through time but some correlations between behaviours remained stable eg. boldness and aggression in one pop but not other
Correlation emerged in those surviving trout predator (selection favours)
Certain correlations apparent at some developmental stages but not others
Therefore behavioural syndromes don’t necessarily limit behavioural plasticity & ecological and developmental circumstances might favour different suites of traits
Interaction between personality and hunger in fish
When given choice between joining shoal of bold or shoal of shy fish, bold and shy fish both prefer bold shoal
But when hungry, shy fish more likely to go to shy
(no hunger difference in bold fish when hungry)
Spontaneous emergence of leaders and followers in foraging pairs
eg. sticklebacks
Rands et al., 2003
State-dependent, dynamic game model of foraging by a pair- each chose whether it should rest or forage at a given moment (to maximise own survival)
When advantage to foraging together, equilibrium behaviour of both becomes synchronised, which causes differences in the energetic reserves of the two individuals- causes them to take on different roles
Individual with lowest reserves = pace-maker, determines when pair should forage according to own needs
Group coordination needs no knowledge of the state of others- use own state
If low resources, go forage
If relatively high resources and partner forages, join, because (depending on resource abundance) will be advantageous to you (usually positive feedback)
Only if really high resources don’t need to forage
How life history trade offs favour evolution of personalities
Wolf et al., 2007
Trade off between current and future reproduction => polymorphic pops where some individuals put more emphasis on future reproduction that others (may be related to resource levels)
Individuals with high future expectations have much to lose will be more risk-averse than those with low expectations
Causes different behavioural types, behavioural consistency and correlations of behaviours across contexts.
Explains common finding that explorative behaviour and risk taking traits such as aggression and boldness are common characteristics of animal personality
How resources affect boldness in hermit crabs
Bolder (less time to reemerge from shell after scared) individuals have smaller spermatophores than shy
Fewer resources, less to lose, less careful
Consistent at 2 different locations
Evolution of intrinsic leadership
Johnstone & Manica, 2011
Leadership is solution for maintaining group coordination when members of a group differ in preferred course of action
intrinsic leadership = lambda, determines probability of choosing own preference over following another individual
cost, k, determines cost of following
Repeated coordination games
Benefits maximised when individual imposes its choice on a group and is followed
selection leads to evolutionary branching and diversification in intrinsic leadership among the members of a population even in the absence of any variation in state
changes in k don’t affect lambda much unless extreme
in groups of 2, multiple equilibria exist
in groups of more than 2, 2 equilibria appear- leaders and followers evolve (dimorphism)
Personality types maintained by frequency-dependent selection (leaders gain by imposing their preferences on followers, but fail to coordinate effectively when interacting with other leaders)
Fraction of intrinsic leaders in group increases with decreasing conflict - low conflict, many intrinsic followers and coordination achieved by random convergence on one leaders option
High conflict- most intrinsic leaders and coordination can break down
Co-evolution of behaviour and state variables
eg. changes in aggressiveness with metabolic capacity
Wold & McNamara, 2012
Hawk-Dove game, where metabolism affects aggressiveness:
When cost of high metabolism is high, all have low metabolism
When costs aren’t too high, coexistence of some individuals with high and some with low metabolism
High aggression can give gains needed to afford high metabolism- but only if costs limited and chances of winning in game are high ie. likely to come up against low aggression individual
=Mixed ESS
Can lead to behavioural syndromes
Therefore, coevolution of behavioural and physiological traits also gives rise to adaptive physiological differences that are systematically associated with behavioural differences
Personality and transcriptomics in zebrafish
Rey et al., 2013
Consistent behavioural differences in WT= proactive and reactive (bold and shy) - persist over time and context relates to underlying differences in regulated gene networks and predicted protein–protein interactions - differences can be mapped to distinct regions of the brain
variation in gene expression between individuals accounts for >9% of observed variation in the brain transcriptome
Interactome analysis of personalities
Rev et al., 2013
Focus on groups of genes that interact
For proactive and reactive individuals, certain pathways have similar levels f upregulation eg. Notch signalling
But others have different levels eg. DNA replication/DNA strand elongation
These levels different in fore and hind brain
Sub-networks specific to different brain parts are expressed differently in the 2 behavioural types (but what does this actually mean?)
Pace of life syndrome
specifies that closely related species or populations experiencing different ecological conditions should differ in a suite of metabolic, hormonal and immunity traits that have coevolved with the life-history particularities related to these conditions
consistent individual differences also covary with life history and physiological differences at the within-population, interpopulation and interspecific levels (Reale et al., 2010)
eg. in domestic dogs (which have undergone extensive artificial selection) life history relates to personality:
obedient (or docile, shy) breeds live longer than disobedient (or bold) ones and that aggressive breeds have higher energy needs than unaggressive ones
these correlations likely due to correlated responses to artificial selection on personality (Careau et al., 2010)
eg. boldness predicts predation of pigeons by raptors
data from 27 GPS tracked homing pigeons - very strong effects despite small sample size
Larger and darker pigeons more likely to be predated, plus when shorter flight initiation distance, and lower escape reaction time
genetic correlations between animal personalities and nonbehavioural traits in zebrafish
Kern et al., 2016
Associations between personality, morphology and locomotor performance
Zebrafish caught in wild and then selectively bred to have proactive or reactive stress-coping style
After 4-7 generations, morphology and locomotor performance differed between personality lines: bold zebrafish exhibited a larger caudal region and higher fast-start performance than fish in the shy line
Stronger difference in females
Correlated response of locomotor performance likely due to pleiotropy or physical gene linkage
Correlated response of body shape may be due to linkage disequilibrium
Boldness and catchability of bluegill sunfish
Kern et al., 2016
Size-selective harvesting associated with commercial and recreational fishing practices has been shown to alter life history traits through a phenomenon known as fishing-induced evolution
due to direct or indirect correlations between behaviour and life history
Juvenile Bluegill Sunfish caught by using seine net or a lure (angled) tested for boldness, water column use and activity
Fish caught by angling more timid and had fewer ectoparasites
Therefore fishing techniques can affect population demographics -conservation implication
Evolutionary consequences of personalities in social spiders
Grinsted et al., 2013
Indian cooperative spider
Task differentiation in simulated prey capture attempts cross 10-day behavioural assays in the field, independent of developmental stage
Participation in prey capture positively correlated with level of boldness but not aggression
Body size positively correlated with being the first spider to emerge from the colony as a response to prey capture but not with being the first to attack
Boldness and aggression are positively correlated, but neither correlate with body size or developmental stage
Spider groups of all asocial or all social problematic, need a mix for highest RS
within mixed colonies, social and asocial equally successful because of task specialisation
asocial= aggressive- prey capture and group protection
social=parental care, raining offspring
having a high density of asocial even in a mixed colony is bad because aggressive to each other
Behavioural synchrony in chacma baboons
Leading individuals get large foraging benefits (first to arrive at food)- dominant individuals tend to lead, social affiliation to leader mediates arrival order
King et al., 2008
probability of a group being synchronized increased with the number of pregnant females, but decreased with the number of sexually swollen females in a group
Synchrony also declined throughout the day
Due to changes in activity budget of both sexes related to reproductive strategies & changing levels of satiation in individuals
synchrony was highest in a ‘closed’ woodland habitat, and lowest in ‘open’ desert habitat
due to habitat differences in food patch configuration and/or predation risk
Social feedback in emergence of leaders in sticklebacks
Harcourt et al., 2009
2 chambered tank- one fish either side, each has safe area and open feeding area
with opaque barrier, can establish which are bolder, which are shyer
Experimental set up with transparent barrier and randomly paired fish of different boldness either side
Markov chain model to infer the individual rules underlying their joint behaviour
Each responded to each others movements- if one foraging, other more likely to forage, if one returns to cover other more likely to follow
But bolder individuals displayed greater initiative and less responsive to partners (and more determination-out for longer), shyer individuals the opposite- followed faithfully
Shyer individuals, as followers, also elicited greater leadership tendencies in partner (therefore positive social feedback)
Nakayama et al., (2010)- success in recruiting a partner affects an individual’s tendency to initiate the next trip, if successful, more likely to initiate subsequent trip and be less responsive to partner
bold fish were unaffected by failures to initiate a joint trip, shy individuals were less likely to attempt another initiation after a failure
How hunger affects leadership roles in sticklebacks
Nakayama et al., 2012
Measured tendency to initiate foraging trip in bold and shy individuals before and after satiating just one of them
Before- bold = leader
After, depending on which fed
If fed shy, became less active but bold didn’t change behaviour and continued to lead
If fed bold, it initiated fewer trips, so shy began to initiate more more frequently
In pairs that only differed a bit in temperament, observed role reversal
Foraging initiation dynamics in groups of sticklebacks
3 fish, 1 bold, 1 shy, 1 focal
2 treatments: focal= shy and focal= bold
Shy focal fish:
no fish out, tendency to leave low
bold fish only out, tendency to follow
shy fish only out, greater tendency to follow
both fish out, greatest tendency to follow
Pay more attention to those with similar personalities
Bold focal fish:
similar pattern by more noise, not as statistically clear
Conflicts over direction of foraging in sticklebacks
Harcourt et al., 2010
Pairs prefer to synchronise trips because reduces perceived predation risk
fish trained to expect food at one of two alternate locations, paired fish with different expectations
Compared to isolated individuals members of a pair showed increased tendency to alternate between foraging sites, taking it in turns to visit each one’s preferred site
Markov chain model suggests that fish respond to a partner that breaks the pattern of alternation by themselves reverting to less regular behaviour
Here, pattern of alternation is actively monitored and maintained
How personality affects collective behaviour
Groups must be 5+
Jolles et al., 2017
Open arena,
sociability predicts spatial positioning and leadership in social contexts, no effect of boldness
more social fish, more time in centre and less in periphery
less social more likely to lead
level of sociability in group can affect its aggregation- if all sociable, would cause swarm because overly responsive to each other
If add food patch of area of cover into arena, now there is a goal
Both sociability and boldness predict foraging success
bolder and less sociable fish get the most (more time away from group, can find more), more sociable, just follow others round and achieve less (boldness has less of an effect in more sociable individuals)
Decision making in honeybee nest sites
use waggle dance to indicate potential locations
if 1 nest box available, quick decision made
but if eg. 5, can take ~5 hours to reach decision
Quorum sensing:
Scouting
Dancing (info passed from scouts to naïve) once reached a certain level…
Piping (by queen- makes continuous noise)
Leaving and head to new nest
Process figures out which site preferred overall
Quorum sensing, ants looking for nest
Progressive
Decision made once threshold reached
Scouts start with tandem runs (lead naïve individual to nest)
Follow up with transporting eggs and other individuals
Then nest moves (phase shift)
=shared decision but only part of pop involved in scouting (2/3 of pop don’t recruit others)
Decision based on number of ants in new nest
System very stochastic
Quorum decisions in sticklebacks
Benefits of consensus decisions: maintenance of group cohesion, enhancement of decision accuracy compared with lone individuals and improvement in decision speed
Sumpter & Pratt, 2008
Choice between 2 model fish (1 more attractive than other)
Given time, choose attractive one
But if show very quickly, some will pick other one
If more individuals in a group shown, more likely to follow attractive model
An individual’s probability of exhibiting a behaviour is a sharply nonlinear function of the number of other individuals already performing this behaviour
Results match well with quorum-consensus model (based on the concordant theorem)
Directional decisions in baboons
track movements with radio collars
Decision to follow is dependent on number of initiators and whether they all initiated in same direction or not (more likely to follow if many in same direction)
Compromise vs choice depends on angle between initiations - is low angle, compromise, if large, go with majority
Role of uninformed individuals in group decision making eg. golden shiners
uninformed individuals can prevent a few opinionated individuals from hijacking decisions- still have to reach a majority decision
eg. release fish from holders- aim for blue or yellow target
minority trained to go to incorrect target
increasing number of uninformed prevents overruling, group goes to preferred despite strongly opinionated individuals
Group level consistency in ants
Aphaenogaster senilis
correlation between exploratory activity and brood rescue behaviour
Brood rescue predicts colony growth
Personality vs experience in foraging sticklebacks
Leaving cover and crossing dangerous area (when leaving and how quick to cross) to feed affected by social context and experience
Groups cross faster, feel safer (larger group = faster)
Groups w experience of group cross faster than individuals with experience
Leaving cover on first social trial affected by personality, but effect disappears on second trial (no effect on crossing)
Increasing experience with group, build up group behaviour, becomes more and more different from individual behaviours
Crossing= experience trumps personality
But boldness still predicts feeding success irrespective of experience
consistent individual difference depend on context
Buchnera
primary symbiont of aphids
not in other insect groups
aphids do poorly without it
Pasteuria parasite of Daphnia
significant genetic variation in Daphnia clone susceptibility and Pasteuria infectivity
strong reciprocal selective pressure because infected Daphnia sterile and parasites need host to transmit
Pasteuria castrates host and redirects resources to growth- larger hosts can contain more parasite spores
intermediate virulence optimal because too low= too slow, too high= can’t get as many spores in host
Caterpillar - ant mutualism
Lycaenid caterpillars secrete honeydew that ants drink
ants defend caterpillars against parasitic wasps
co-adaptations
Crossbill beak coevolution
Prefer smaller lodgepole pine cones because easier to de-seed
Driven increased cone width, mass and length where only crossbills present
Causes increased crossbill beak size, those with bigger beaks better survival
Unless squirrels also present- grater selection pressure on lodgepole cones because remove cone from tree and eat it from base (crossbills eat from opposite end)
Therefore haven’t driven larger cones when both present
Snail and trematode coevolution
New Zealand
Freshwater snails infected by castrating trematode (Microphallus spp.) parasite (snails not definitive host, infective stage released into ducks when they eat snails)
snails infected by eggs, larvae develop in snails- duck consumption needed to complete life cycle, therefore snails inaccessible to ducks (deep) may be less affected
Experiment:
expose shallow and deep snails to sympatric (coevolving w shallow snails) and allopatric (non-evolving) parasites- measure infection prevalence
parasites only adapted to and able to infect shallow snails
Parasites best at infecting the most common snail genotypes
Host genetic background therefore changing over time
Jokela et al., 2009
cycling of gene frequencies in snail pop appears to be driven by parasites- evolution of more resistant snails and loss of most vulnerable
The Red Queen hypothesis postulates that high infection rates in the common asexual clones could periodically favour the genetically diverse sexual individuals and promote the short‐term coexistence of sexual and asexual populations
In study of snails, within 7–10 years, the most common clones were almost completely replaced by initially rare clones in two different habitats, and sexuals persisted throughout
Sexuals more common in shallows and asexuals more common in deep, supports Red Queen (King et al., 2011)
Parasites that encounter a resistant host are often killed (strong reciprocal selection)- secondary infections (needed for parasite survival) only happen in <3% of cases
Experimental coevolution in Bacteria and Phage
Pseudomonas bacteria and phi-2 phage
Poullain et al., 2007
The ability of coevolved phage isolates to infect coevolved bacteria host varies across populations
At the phage population level, coevolution led to the evolution of broader infectivity range, but without an associated decrease in phage growth rate relative to the ancestor, whereas phage evolution in the absence of bacterial evolution led to an increased growth rate but no increase in infectivity range
Brockhurst et al., 2007
Time shift assay:
bacteria from past, present and future (1 transfer difference) were exposed to phage taken from a single transfer
bacteria evolved increased resistance to phage infection over time - both resistance and phage infectivity increased with time
Paterson et al., 2010:
coevolve Pseudomonas and bacteriophage, monitor phage molecule evolution
pathogens evolve more rapidly in coevolution that when alone
Future bacteria best at resisting contemporary parasites
Predator prey arms race- newts and snakes
Rough-skinned newts have powerful anti predator toxins (TTX)- 100x more powerful than necessary to kill
Garter snakes= their major predator- evolved resistance to TTX (Brodie et al., 2002)
snake resistance is predicted by newt toxicity
some pops have drastically increased TTX resistance, others haven’t (hotspots with 100% snake resistance, others with 0% resistance)- depends on arms race & importance of ecological effects in different geographic locations
Red Queen coevolution in snails and trematodes
trematodes can only infect snails with specific ‘matching’ genotype
rare snail genotypes therefore should be less frequently infected than common
Red queen coevolution in Daphnia and Pasteuria
if infected, not reproducing
if don’t infect, don’t pass on therefore v strong reciprocal evolution
Decastecker et al., 2007 experiment:
Resting eggs and bacterial spores fall to bottom of lakes- covered in lake sediments
produces fossil record
extract ‘sediment core’, contains isolated hosts and parasites from over a 4 year period
Do past and future parasites match contemporary host?
Contemporary parasites best at infecting (because coevolved to)
Never see resistance or infectivity ever reach 100%
Snail resistance to past and future parasites decreases with increasing resistance to contemporary
Reciprocal selection in interspecifically competing three spined sticklebacks
Inhabit post glacial lakes in British Columbia
2 morphs:
Limnetic (shallow)
Benthic (deep)
some lakes have both, some have 1 solitary intermediate morph
Measured fitness effects of competition between ‘ancestral’ intermediates and limnetics (biggest ecological competitor) from a lake w both (Schluter, 1994)
Expect competition with limnetics, selection towards benthic form
Tested for:
stabilising selection without competition
directional selection towards benthic form w competition
coexistence- reciprocal selection for divergence in body size
Competition promoted v rapid morphological diversification in just 3 months- strength of comp between mediated by phenotypic similarity
E. coli character displacement
Richard Lenski’s E. coli- 12 flasks of E. coli in glucose-limited environment, since 1988, transfer 1% into new flask every day, by about 50k generations, 70% of pops fitter
see same genes mutating and phenotypic changes in different populations- lots of synonymous mutations, all occurring in same genes, suggesting natural selection was finding the same path and potentially the genes had good pleiotrophy
at 30,000 generations, Cit+ evolved, bacteria booming- strain evolved mutations to metabolise citrate in medium
Co-phylogeny of birds and feather lice
see 7 cospeciation events and 3 host switches (may be due to extinction)
Co-phylogeny of aphids and Buchnera
intracellular endosymbionts
synthesise essential amino acids, can’t survive outside cells, genes completely interlinked in metabolic processes
100-250 My association
co-phylogeny v well matched (Clark et al., 2000)
Sap feeders and mutualists for essential amino acids
Aphids and Buchnera Psyllids and Carsonella Mealybugs and Tremblaya Sharpshooters and Baumania Whitefly and Portiera Cicadas and Sulcia and Hodgkinia Hoppers and Sulcia
Vertebrate blood suckers and mutualists for B vitamins
Tsetse fly and Wigglesworthia
Assassin bug and Rhodococcus
Bed bug and Wolbachia
Secondary endosymbionts in pea aphid
Fungus resistance - Hamiltonella
Parasitoid resistance - Rickettsia, Ricketsiella, Spiroplasmia
Heat tolerance - Serratia, Hamiltonella, Regiella
Body colour - Ricketsiella
Host plant adaptation - Regiella
Wolbachia as parasite and mutualist
Thought to infect over 60% of insect species
mutualist in nematodea
male embryo killer in blue moon butterfly (in some pops, female: male =100:1)
mutualist in bed bugs- vitamin B provider (Hosokawa et al., 2010- development stunted when Wolbachia experimentally removed w antibiotics- eggs fail to develop- rescued by providing vitamin B)
Helicobacter pylori
causes stomach cancers and stomach ulcers
but protects against oesophageal cancer
Microbiome in lepidotrichia on mutualist-parasite continuum
Bt insecticide for lepidopteran pests- rapid death from punching holes in gut not from starving to death but microbiome entering blood and causing sepsis (treat w antibiotics prior to Bt- mortality down from 100 to ~10%)
Broderick et al., 20066
Systemic inflammatory response
response to mitochondria in wrong place eg. with severe cut or bruise and cells split open=> bloodstream
Huge inflammatory response
Myxomatosis in European rabbit
Release of 24 wild rabbits, 1859- ate all vegetation
fencing, poisoning, hunting all unsuccessful to control pops
Pox virus that killed European rabbits identified- released in 1950, spread 2000km in 3 months
1900 - 3 million rabbits
1959 - 24
99% fatality rate
pop reductions of 40-99.8%
Comparison of original released pox strain w that in rabbits later- had evolved to different strains with lower virulence- had been to virulent to transmit (stabilising selection)
through time, evolution of rabbit resistance
compare museum and wild-caught samples from last 150 years (1800s-2013), same genetic adaptations in 3 different parts of the world (UK, mainland Europe, Australia)
sequenced nearly 20,000 genes to pinpoint mutations that emerged since 1850s- many of the genes that have changes played a key role in rabbit immune system
Transmission strategy in nematode parasites of fig wasps
wasps oviposit offspring into fig ovule, which develop, emerge and mate
wasps pollinate figs
nematode parasites infect female wasps and kill
released from female cadaver and infect offspring (vertical) and others (horizontal)
vertical only, if 1 female oviposits inside egg
variation in strategy depends on fig wasp behaviour (eg. number wasps per fig)
greater proportion of figs with 1 wasp = increased relative fecundity
worms that infect wasps that produce single foundress broods have lower virulence (because not horizontal)
???
Ancient asexual lineages
how do they avoid death from coevolving pathogens?
eg. bdelloid rotifers- dessication to esape pathogens on dispersal (anhydrobiosis)
If disperse ‘dry’ by wind, lose fungal pathogens
During anhydrobiosis, genomes physically fragment and generate novelty- repair includes lots of environmental DNA- use this novel material in adaptation
Parthenogenetic vulnerability to pathogens
Moritz et al., 2001
Part of the Red Queen hypothesis suggests that sexual reproduction is maintained in populations because of the need to continually create genotypes that confer resistance against rapidly evolving pathogens and parasites
Parthenogenetic individuals of the prickly gecko, Heteronotia binoei, are much more prone to infection by mites than are their sexual relatives
This is consistent across localities with different combinations of parthenogenetic genotypes and sexual chromosome races and occurs despite the unusually high genetic diversity of the parthenogenetic form
Kin discrimination egs.
Slime moulds -depends on surface adhesion proteins (direct)
Long tailed tits- vocal patterns (imprinted, indirect)
Ground squirrels - olfactory cues w genetic component (armpit hypothesis- direct and indirect)
Malarial parasites - ??? (know they do somehow, adjust their investment into male and female transmission stages according to the number of conspecifics sharing host)- maybe via host immune response?
Virulence differences in malaria
mixed genotype infections cause lower RBC count and greater weight loss in mice- more virulent
suggests immune system less able to control antigenic diversity
mounting immune response against more than 1 parasite genotype more costly (Taylor et al., 1998)
due to increased replication of transmission stages of Plasmodium- overwhelms immune system
Public goods cooperation
Pathogenic bacteria Pseudomonas aeruginosa
produces costly siderophores= iron-scavenging molecules, beneficial to growth
Cooperation favoured by high relatedness of infecting bacteria and low competition between them- more related, increased siderophore production
Relatedness determining quorum sensing in Pseudomonas
Mouse system
Quorum sensing favoured by high relatedness of bacteria in mouse
Mouse mortality rate higher in high relatedness treatment
Infections by QS bacteria grew to higher densities
Coevolution with diverse pathogen communities
experimental evolution of 5 different phages in different mixes and monoculture
determined whether coevo took place using 13,500 time-shift assays (Betts et al., 2018)
diverse parasite communities accelerated host evolution
parasite from future more infective
hosts evolved increased resistance
diverse community therefore = increased community
more diverse communities more likely to contain high selective force
Bacteria evolved resistance by modifying cell surface making pathogen attachment harder
In response, phages modified structures so can attach
Increased parasite diversity drove shifts from Red Queen dynamics to arms race dynamics
Characterised by a selective sweep of SNPs for generalist resistance mutations in genes of host bacterium cell surface lipopolysaccharide (bacteriophage receptor) - strategy suitable for variety of enemies, maintaining resistance to specific parasites slow and less effective
drove faster molecular evolution in host pops and greater genetic divergence among pops
therefore exposure to multiple parasites influences rate and type of host-parasite coevo
parasites also evolve greater infectivity
parasite communities = hotspots for antagonistic coevolution
increased parasite diversity = more alleles reaching fixation (stronger arms race)
Interspecific competition of malaria and hookworms
Mass de-worming programmes to treat hookworms exacerbated intensity of malaria by 2-3x
study of 4000 people in Indonesia w coinfection
competition for RBCs
Also strain effect, P. vivax less competitive than P. falciparum
therefore modify treatments accordingly- in areas where P. vivax common, should test for malaria before giving deworming treatment
Interspecific competition of bacteria in nematodes
Microbe mediated host defence drives evo of reduced pathogen virulence
In C. elegans, infect w Staphylococcus aureus (“bad”) and “good” gut bacteria (defensive mutualist) Enterococcus faecalis
When coinfected, good defends against bad and use siderophores, causes bad to reduce siderophore production, evolve to be less harmful
Adaptive mutualism evolves
Staph kills ~50-100% after 24hrs
Enterococcus kills ~1% after one week
But together, intermediate virulence- worm survival from 52% to 82%, occurred quickly (can see changes by generation 5)
Good could defend against different staph strains
Found mutation in E. faecalis associated with superoxide production, harmful to staph
Therefore coinfections drove C. elegans evo
Coevolving bacteria with nematode= changes in in both worm and its gut bacteria- in presence of parasite, all three evolved together to increase worm survival
host adapted by accommodating increased number of protective bacteria (more susceptible)
If amount of host protection too low, also still slightly virulent so not worth having
but if too high then other microbes may be wiped out, removing the need for protection
????
Effect of phage on horse chestnut trees and bleeding canker
sampled 4 leaves from each of 8 trees
looked at interior and exterior bacterial diversity (much higher within due to phage control)
isolate bacteria from surface and inside, expose to phage
Phage do much better on their local bacteria (p<0.0001)
No difference in scale of interactions between leaves within same tree
Time shift experiment to determine whether coevolution:
6 time points, 8 trees, 24 bacteria per tree:
bacteria evolved increased resistance to phages of past than future
phages do best on bacteria from same month or recent past
Horse chestnut trees with lower microbiome bacterial diversity more likely to have canker, and related to disease severity
shifting bacterial community composition associates with disease (not driven by any one in particular)
Bacteriocytes in insects
Stoll et al., 2010
have repeatedly evolved in several lineages with same function of containing and controlling bacterial symbionts- hide them from immune system and stop them spreading into other tissue
but these beneficial symbionts can be harmful elsewhere in body
Phage and mucus in controlling vertebrate symbionts
mucus is quite impenetrable
phage 15x more likely to find bacteria host if stuck to mucus
mucus universal to all animals; phage universal to all mucus (always more phage than bacteria)
original immune system
Cooperation as anti predator response in algae
3 different algae have 3 different predators, but if predators present, algae group together
exposure to predator poo also induces grouping
Correlations between symbiont function, transmission mode, genome size and host dependence
106 symbioses- bacterial symbionts and host
MCMC glmm comparative analysis and bacterial host phylogenies used
both transmission mode and symbiont function correlate with host dependence - vertical transmission and nutritional symbionts = higher host dependence
decrease in host fitness greatest for loss of nutrient provisioning, vertically transmitted removed
negative correlation of host dependence and symbiont genome size in vertically but not horizontally transmitted- therefore function and pop structure important in driving irreversible dependence between hosts and symbionts
Cicadas and Hodgkinia symbiont
13 years underground as nymph, emerge, reproduce and die
Symbiont has split into separate completely complementary species within cicada (now ~ 15-70)- only survive if all present
reduced genome because in tight coevolution (black queen hypothesis)
risky because now ocked in coevo dynamic
Speciation by symbiosis
Symbiogenesis
eg. 2 spp of wol+ fig wasps, Nasonia giraulti and longiconis
Have different strains of Wolbachia
Reproductive isolation curable with antibiotics- death by distorted hologenome
normally, mating => cytoplasmic incompatibility due to clashing wolbachia strains
Or could it just be because hybrids have faulty immune systems that leave them vulnerable to any bacteria?
shouldn’t be able to change a genotype with an antibiotic
Ant - acacia twisted symbiosis
ants defend from grazers in return for honeydew and protection
BUT appears mutualists, but enzyme prevents ant digesting other sugars, enslaved
examples of indirect harm from good microbes
Inadvertent lures released by aphid microbes for predatory hoverflies
Poliovirus attaches to microbiome bacteria to gain access to host cells
Mouse mammary tumour virus attaches to microbiome to disguise from immune system
Dysbiosis in coral
Coral bleaching
Warming causes coral to expel algae, makes coral weaker
Acidification decreases saturation state of aragonite, not as energetically favourable/available to build coral skeleton
Get diseases eg. white pox, black band, pink line, red band
Banana clones
Gros Michel banana clone wiped out by 2 fungi
New Cavendish clone, but now a new worse fungus has developed- risk
Infectious diseases from animals to humans
influenza H1N1 from pigs and birds, <0.1% fatality rate
HIV-1 from primates, 100% fatality rate
SARS Corona virus from bats, 10% fatality rate
more likely as species ranges change with climate change
Loss of coevolutionary hotspots
Climate change = range changes
As geographical range of a parasite increases, becomes maladaptive to host
Parasite adaptation is inversely proportional to fraction of a host’s range it occupies
Loss of hotspots
Fecal microbial transplants (FMT)
harnessing coevolution
to restore beneficial microbial gut community eg. for people on long-term antibiotic treatment/chemotherapy
But is it a drug or organ donation? will affect its availability- how food and drug administration regulates procedure, how much it costs and who profits
Harnessing defensive symbionts in Drosophila
infected by nematodes and Spiroplasma
Spiroplasma provides resistance to nematodes by encoding a Ribsome Inactivating Protein which cleaves specific sequences of ribosomal RNA of nematode but not insect
Symbiosis so beneficial that it has spread trough many pops - enhances fertility 10-fold compared to unprotected flies
Wolbachia in Drosophila
Wolbachia increases Drosophila resistance to broad range of RNA viruses, but also manipulated host reproduction by inducing cytoplasmic incompatibility
Transmitted vertically from infected female to offspring (males = deadend)
When male infected, sperm modified so embryo dies early in development
But in females, encodes a 2nd factor that rescues embryo
Therefore Wolbachia infected females have reproductive advantage, bacterium can invade pops and be maintained
Wolbachia as biocontrol
Wolbachia decreases ability of mosquitos to carry and transmit Dengue and Zika virus
Large scale releases of Wolbachia infected mosquitos underway
Soil bioremediation
Siderophores scavenge metals (free iron) from environment
a ‘public good’ in microbial communities
can lead to cheating in P. fluorescens
But community species sorting selects for high producing species- so intermediate levels of cooperation favoured
Heavy metal contamination global problem
In nature,
94 samples across heavy metal gradient
samples analysed for heavy metal content, pH, bacterial composition, proportion siderophore-producing bacteria per sample, bacterial density (16S RNA)
positive correlation between heavy metal content and siderophore production
cheating probably doesn’t matter (but only a correlation)
In lab, Hesse et al., 2018:
experimental evolution of natural compost communities
after 3&6 weeks, sampled 24 clones per microcosm for siderophore production
Production higher in cooper contaminated microcosms
no obvious effects of cheating
????
Darwinian medicine
Manipulate natural pathogens to decrease virulence
eg. C. diphtheriae causes dihtheria, there are multiple strains
virulent strains produce toxin, avirulent don’t
toxin is costly to produce but helps it to obtain resources
Vaccinations that target toxins means net cost of producing, therefore outcompeted by avirulent
But danger they might increase virulence
vaccines against Plasmodium slow parasite growth but don’t stop it
could cause it to evolve higher intrinsic replication rate in compensation, could make it more virulent to unvaccinated people
Shrimp and goby symbiosis
Blind shrimp digs burrow
Goby guards and when predator comes warns shrimp with tactile communication (flick w tail), hide together
don’t know enough to call coevo
Moray eel and grouper symbiosis
cooperative hunting in coral reefs
grouper = fast
moray eel can fit between rocks
corner prey
referential gesture of grouper with face to indicate where prey is
to demonstrate that gesture is due to coevo need to show = an adaptation (that grouper does because of association and that eel responds because of association)
Sibling conflict in Egrets
Mock, 1987
Siblicidal species
sibling aggression was significantly lower in two-chick broods than 3-chick broods
when larger broods, parents don’t interfere with sibling fights but their presence seems to subtly decrease aggression (fewer “sever” fights occurred when parents were present)
No favouritism of food distribution to dying chick victims
Interpretation difficult, could mean one of two things:
Either evolutionary conflict exists and offspring are winning or there is no conflict
If no conflict, parents create asymmetries between offspring (eg. via hatch asynchrony) then leaving sibling conflict to run its course without further intervention – siblicide and other investment-skewing selfish chick behaviours may serve parental interests well (equal allocation of resources likely to not be parental optimum)
Mating in house cricket
(Head et al., 2005)
Acheta domesticus
Mated females with attractive or unattractive males, fitness components combined to give relative estimates for number of grandchildren produced
females mated to attractive males incur a substantial survival cost, however costs are cancelled out and may be outweighed by the benefits of having offspring with elevated fitness
Mostly due to increasing attractiveness of sons
This reveals the value of estimating the net fitness consequences of a mating strategy by including measures of offspring quality in estimates of fitness
Dishonest signalling in green frogs
Bee et al., 2000
Rana clamitans
Males broadcast calls to conspecifics in order to defend their territories
Smaller male frogs have been observed to lower the dominant frequency of their calls in response to the low
frequency calls of large male frogs, in order to give the appearance of being larger than in reality and maintain territory dominance
when played the calls of smaller frogs, the relative lowering of frequency is less extreme, demonstrating that this behaviour isn’t a standard response to territorial contests, and instead a dishonest signal they
produce to manipulate the outcome of contests that are not in their favour
Alarm signals in cichlid fish
Rubenstein et al., 2012
Injured fish produce alarm signals that signal danger to nearby conspecifics, increasing their chances of responding and surviving
In fish that shoal with close kin, such communication could have inclusive fitness benefits to the signaller
Status signals in Harris’s sparrows
Halliday & Slater, 1983
black patches on a bird’s throat and
breast signals its status.
Experiments- pale birds’ breasts are dyed black = increase their success against subordinates,
but dominant birds are able to detect them from their behaviour and are more aggressive towards them as a result
therefore cost selecting against dishonesty
Scorpionfly frequency dependent dishonesty
Halliday & Slater, 1983
females choose males to mate with dependent on the size of the nuptial gift they present
Occasionally, males manipulate rival
males into handing over their gifts by mimicking a sexually receptive female and subsequently use
the gift as their own to acquire matings- but this only happens infrequently compared to encountering receptive female, less costly to be deceived occasionally
Frequency dependent cheating in cooperative leaf cutter ants
Hughes et al., 2008
most significant potential conflict in social insect colonies is over which individuals become reproductive queens rather than sterile workers
individual larvae will maximize their fitness by becoming queens whereas their nestmates will generally maximize fitness by forcing larvae to become workers – evolutionary constraints are thought to prevent cheating by removing genetic variation in caste propensity
However, one-fifth of leaf-cutting ant patrilines cheat their nestmates by biasing their larval development toward becoming queens rather than workers
Mechanisms = general tendency to become larger adult, and relating to worker-queen developmental switch
“royal” genotypes are rare both in the population and within individual colonies, to avoid suppression by cooperative genotypes, the efficiency of which is frequency-dependent
Therefore cheating can be widespread in even the most cooperative of societies
Piwi-interacting RNAs
piRNAs, in mammalian cells
mainly in spermatogenic cells in testes, but also ovarian somatic cells and neuron cells in invertebrates, as well as in many other mammalian somatic cells – endogenous system for silencing the expression of selfish genetic elements such as retrotransposons and thus preventing the gene products of such sequences from interfering with germ cell formation
Dark-eyed group vigilance
Pulliam et al., 1982
cooperation in vigilance increases overall group vigilance. Potential for ‘cheating’ and not being vigilant? But, remains as ESS with everyone sharing vigilance, but for selfish reasons- spotting predator first allows
greater chance of escaping.
Yucca - Yucca moth coevolution
Yucca plant pollinated exclusively by yucca moth, which depends entirely on feeding on the plant for survival
Yuccas also provide protection deep within flowers for moth to lay eggs
Rediviva bee - Diascia flower coevolution
Steiner & Whitehead, 1990
South Africa, bees use forelegs to collect oil from Diascia floral spurs, pollinating them in the process
Studies have shows that in several populations mean foreleg length in bees correlates with spur length of specific Diascia population visited
Coevolution of cuckoos and host birds
Between cuckoo trickery and host defences
Host patterns evolve - signatures that are replicable, distinct and hard to forge eg.
Spottiswoode & Stevens, 2012:
egg polymorphisms are extreme in the African tawny-flanked prinia and its parasite, the cuckoo finch
used models of avian visual perception to analyse the appearance of prinia and cuckoo finch eggs from the same location over 40 years
Egg colours of both species have diversified over time, expanding into avian colour space as expected under negative frequency-dependent selection
Host and parasite appear to be closely tracking one another’s evolution, since parasites showed closer colour mimicry of contemporaneous hosts
eg. (Lahti & Lahti, 2002)
Village weaverbird eggs very different between individuals, hypothesised due to cuckoo parasitism
Found that (1) interindividual egg variability permits individuals to discriminate between own and foreign eggs by rejecting eggs in proportion to the difference in appearance from their own; (2) village weavers remember the appearance of their own eggs and do not require a discordancy within their clutch, nor even the presence of one of their own eggs, in order to distinguish a foreign egg as such; and (3) colour and speckling contain the signature information by which village weavers can distinguish their eggs from foreign ones; whereas shape and mass, being less reliable, do not
Lahti, 2005
Introduction of village weaverbirds onto islands lacking cuckoo parasitism, eg. Mauritius one century ago
Here, between-individual variation and within-clutch consistency in egg appearance have both decreased compared to mainland birds
supports the hypothesis that egg appearance in the African village weaver has been maintained by natural selection as a counteradaptation to cuckoo brood parasitism
Enhanced foraging efficiency in cliff swallow colonies
(Brown, 1998)
Nest in colonies that serve as information centres in which unsuccessful individuals locate and then follow successful individuals to aerial insect food resources
In larger colony size:
-increased number swallows departing colony per hour (individuals did not wait as long to locate appropriate foraging associates in large colonies as in small colonies)
-decreased waiting time between an individual’s arrival at its nest and its departure on its next foraging trip
-returned with food for their nestlings more often and brought more food per trip
-nestling body mass at 10 d of age increased significantly with colony size
-adult body mass late in the nesting season during the period of feeding of nestlings increased
Experimental reduction of large Cliff Swallow colonies to the approximate size of small colonies suggested that nestling and adult body mass in these colonies did not vary with colony location
Coevolution of swarms and predator vision
one reason swarms arise is because the presence of multiple moving prey in swarms causes confusion for attacking predators
Using an evolutionary model of a predator–prey system, Olson et al., (2013) show that predator confusion provides a sufficient selection pressure to evolve swarming behaviour in prey
Plus, evolutionary effect of predator confusion on prey could in turn exert pressure on the structure of the predator’s visual field, favouring the frontally oriented, high-resolution visual systems commonly observed in predators that feed on swarming animals
Biofilm cooperation
hard/durable matrix that bacteria live in, produced by quorum sensing
bacteria reliant on it
bacteria in centre can e protected from eg. antibiotics
but hard to get nutrients when in centre
open K+ channels and release K+ to direct glutamate from outer bacteria into centre
=cooperative mechanism
if all bacteria were clones, could it be considered multicellularity?
Background matching and disruptive colouration in crabs
Price et al., 2019
background matching = resembling the colour and pattern of the environment
may be ineffective in complex habitats where matching one patch may lead to increased visibility in other patches
disruptive coloration = disguises body outlines, may be effective against complex backgrounds
tested camouflage strategies of shore crab in rock pools and mudflats (species = highly variable, capable of plastic changes in appearance, and lives in multiple environments)
predator (bird and fish) vision modelling and image analysis to quantify background matching and disruption in crabs from rock pools and mudflats
rock pool individuals had significantly higher edge disruption than mudflat crabs, whereas mudflat crabs more closely matched the substrate than rock pool crabs for colour, luminance, and pattern
expression of camouflage strategies dependent on the visual environment
Costs and benefits of social relationships in the collective motion of bird flocks
Ling et al., 2019
Current understanding of collective behaviour in nature is based largely on models that assume that identical agents obey the same interaction rules, but in reality interactions may be influenced by social relationships among group members
show that social relationships transform local interactions and collective dynamics
tracked individuals’ three-dimensional trajectories within flocks of jackdaws, a species that forms lifelong pair-bonds
flocks contain internal sub-structure, with discrete pairs of individuals tied together by spring-like effective forces
Within flocks, paired birds interacted with fewer neighbours than unpaired birds and flapped their wings more slowly, which may result in energy savings
But, flocks with more paired birds had shorter correlation lengths, which is likely to inhibit efficient information transfer through the flock
This reveal a critical tension between individual- and group-level benefits during collective behaviour in species with differentiated social relationships
Variation in mobbing calls of great tits to different predators
Kalb et al., 2019
Study of great tits in the field presented with taxidermy mounts of predators - tawny owl (low risk), sparrowhawk (high risk)
observed them vary the number of D elements and the interval between those elements;
produced significantly longer D calls with more elements and longer intervals between elements when confronted with a sparrowhawk, as well as a greater number of D calls
suggests that the basic D calls are varied depending on threat intensity
Strategic sperm allocation
When a female is sexually promiscuous, the ejaculates of different males compete for the fertilization of her eggs; the more sperm a male inseminates into a female, the more likely he is to fertilize her eggs. Because sperm production is limited and costly, theory predicts that males will strategically allocate sperm (1) according to female promiscuity (2) saving some for copulations with new females, and (3) to females producing more and/or better offspring
Pizzari et al., 2003
Male fowl show status-dependent sperm investment in females according to the level of female promiscuity; they progressively reduce sperm investment in a particular female but, on encountering a new female, instantaneously increase their sperm investment; and they preferentially allocate sperm to females with large sexual ornaments signalling superior maternal investment
