Behavioural Ecology Flashcards
Explain difference between proximate and ultimate causes of behaviour.
Perhaps use red squirrels or butterfly/moth eyespots as examples
Proximate describes HOW organisms act this way such as their mechanisms and development (ontogeny).
Ultimate describes the root cause, ie. the WHY. This looks at the evolutionary cause and tje function (selective pressure)
What are these 2 main proximate causes for animal behaviour:
1. G——dev——– mechanisms
2. Se——-mo— mechanisms
Try and give examples of these.
- Genetic-devleopmental mechanisms: Such as effect of heredity on behaviour, sensory-motor system development through their environments
- Sensory-motor mechanisms such as nervous systems, hormone systems and skeletal-muscular systems for the response
What did Tinbergen (the creator of the ultimate / proximate causes) do to the wolf-bee? Wa this testing a proximate or an ultimate hypothesis?
Baffled it by moving pinecones away from it’s nest hole when it was out hunting to see if it did indeed circle to identify landmarks before it left home. Tested an PROXIMATE hypothesis.
What was Tinbergen 19– doing with all those eggshells? Was this testing an ultimate or a proximate hypothesis?
- Tested an ULTIMATE hypothesis by seeing that gulls did indeed move eggshells further away from their nests to reduce chick mortality from crows finding their nests.
https://brill.com/view/journals/beh/19/1-2/article-p74_3.xml
What was the experimental design for Vallin et al. 2005 study on Peacock butterflies.
One had no eye spots and sound.
One had eyespots and no sound
One had both
One had both and control paint around the spots
One had niether
One had both and control chunks taken out of the wings.
What were the findings of V—– et al. 20– studies on Peacock Butterflies.
Vallin et al. 2005: Eyespots were what mattered to reduce bluetit predation. Hissing did not matter for bluetits much at all. Hissing may be for bats.
How can we identify the evolutionary history of behaviours?
Can use Apidae bees as an example
Apidae bees.
You look at living members of the phylogeny and see which ancestors share this behaviour. Sometimes they appear to have evolved this behabviour convergently. As we must use the most PARSIMONIOUS methods with phylogenies, this can mean that we have got the phylogenies wrong, as perhaps with the Apidae bees, where swarming n nectar storing seem to have evolved twice, in them and in the honeybees
Which of these bees swarm? Which of them are eusocial? Which transfer nectar?
Euglossinae - Orchid bees
Apinae - Honey bees
Bombinae - Bumble bees
Meliponinae - Stingless bees
All but euglossinae are eusocial
Apinae and Meliponae both show swarming and nectar transfer from foragers to reciuevers.
Eusociality appears to have a single evolutionary origin, but problematically swarming & nectar transfer appear to have evolved twice in apinae and then meliponae. Bombinae evolved before meliponae confusing the phylogeny.
There are many proximate and ultimate hypothesis as to why humans eat sweet things. Give a couple.
These things taste sweet and nice - Proximate
Sugar is an energy source - ultimate
Our ancestors depended on sugar-rich fruits and we inherited them - Ultimate
Our genes shape the development of nerve cells that perceive sweetness and pleasure - Proximate - DEVELOPMENT of nerve cells
The sensory input from taste in the tongue to brain cells reinforces sweetness - Proximate and mechanistic.
Why do Hanuman langars likely commit infanticide?
A new dominant male will commit infanticide to father it’s own children sooner before being overthrown.
Group selection suggests populations with more s–r—– individuals would survive better. Group selection would thus be favoured if i—- compeititon is important and if groups are relatively l–l—– in relation to individual lifespan
self-restraining, intergroup, long-lived
Infanticide is also found in l—, giant w—- and j—–. The last 2 examples are committed by the females.
lions, waterbugs, jacanas
How did Young & Clutton Brock 2006 add to Bell et al. 2014 study on meerkats
Showed that dominant female litters less likely to survive is subordinate females have pups at the same time, thus infanticide made sense
Young and Clutton-Brock 2006 showed that if s—– AND d—— pregnant, litter survival went down even further to –%
subordinate, dominant, 10%
Why may honeybees sacrifice themselves with their stings?
Honey bee workers rarely reproduce anyway
Sacrifice saves their reprodiuctive investment
When sting is impeded, pheromone alerts other bees of intruder to protect nest.
Why may —— fish change sex?
Anthias fish. If NO dominant male, a female stepping in to take his place can suddenly increase her chances of reproductive success
How do garden spiders reduce risk of being Consumed during sex? 2 ways
- Nuptial gifts
- Crab spider may tie down female
The R—– spider shows some unusual behaviour. Why?
The male will place himselves in the (much larger) females jaws as iti is shown that canibalised males copulate longer and have higher paternity than those which do not.
- Mayliane Andrade studied this.
Search images in animals:
How did bluejays react when shown 2 different species of criptid moth compared to just one?
Improved when presented with images of 1 species, not both
What did Tinbergen observes about Passerine birds (bluetits and that) and search images?
Tinbergen observed that when a new type of caterpillar appeared in woodlands, birds rarely brought it back to nest. When a couple had been found, many more collected then.
Thus hypothesised the birds were building up a search image.
What did young skunks show us about how they find food by smell?
Could find & detect food from longer distances as they gained experience
Looking at lizard phylogenies can show us when vision/a—- foraging and olfaciont/s—– foraging diverged. A rooted o—- is used for comparison
ambush, searching
How are social insects and other group animals different in their foraging techniques? D——– Vs i——- foraging
- Insects are related. Wolves and such often aren’t.
- Insects use deliberate communication
- Wolves and such use incidental communication instead (watching foragers). They can thus take on prey bigger than themselves.
K— v– F—- investigated the waggle dance.
The r—– dance is done if food <50m
The f—–of e—– dance is done if food is >50m.
D—— obtained by angle of bee on vertical cones transposed to the sun.
D—– is obtained on how long it takes to perform dance
Karl Von Frisch, Round, Figure of eight, Direction, Distance
Karl Von Frisch saw how bees communicate distance by creating irregularly p—– tunnels to confuse bees. These bees thought the distance was l—— than it actually was so did significantly less r—- dances. Thus we know bees use visual cues to determine distance. What mechanism did bees do this by\?
patterned, longer, round.
- Showed that it was a NEUROMECHANISM in bees which was used to infer distance
T/F bee foragers found food faster when waggle dance was used.
FALSE, just found better QUALITY food. Thus colony only benefits from this behaviour in winter when prey is scarce.
How do researchers know that ospreys rely on eachother for direction of a fish shoal?
Saw that signifiantly more ospreys headed off in the direction of one which has eeturned with an alewife fish than just a random one.
Informed birds found food faster than naive ones.
Why don’t swallows benefit from getting ‘help’ finding prey? Clue: t—— e—-
Their prey is TEMPORARILY EPHEMERAL. Flies move about loads.
Why don’t groups of female lions and other hunting carnivores disband in times of food scarcity, even though their strategy stops being useful then? Who studied this on what species
Creel & Creel hypothesised that it may REDUCE energy cost from chasing prey etc. African wild dogs DFO show that net energy gain INCREASED in larger packs.
Special reading 2: B— et al. 20–, Suppressing subordinate reproduction provides benefits to dominants in cooperative societies of meerkats.
What did they do to maje this study?
What did they find?
Bell et al. 2014
They used contraceptive injections to stop subordinated reproducing
Weight and health of dominant meerkats pups then shown to significantly increase.
Showed that doms benefitted when they were aggresive to subs to stop them reproducing.
Foraging more effective & aggression lower when subs had no pups.
Showed this behaviour was indeed an adaptive strat for the dominant meerkats.
Special Reading 3: D— et al. 20–. About sand goby and infanticide.
1. When do male sand gobies commit infanticide?
2. Why do they?
3. What does this show?
Deal et al. 2017
1. Signifcantly more likely to when shown more ‘predator cues’. Reduced offspring investment & effort attracting mate.
2. When predators around, prioritise own survival thus may engage in filial cannibalism
3. Shows role of dangerous and uncertain environments in eliciting different levels of paternal investment in this species.
What is sexual deception? Give an example.
Mimicing a sexual signal of another species to exploit it. Such as the Bolas spider using female moth pheromones to attract the male.
Name the 3 main ways in which communication can be honest
- There are common interests in which both parties benefit.
- There is a cost to the signal given out.
- The signals are an index of quality which CANNOT be cheated.
How does common interest communication cause ravens to yell?
Yelling at a carcass if you were NOT in your own territory attracted other non-resident ravens and stopped territory holder from repelling all the others.
Tested by leaving carcasses in woods and observing that the resident ravens did NOT yell if they found a carcass.
How does a cost for communication stop chicks always begging?
Tested on fake nests. A well-fed chick would bhave a SMALL increase in survival for the same amount of food if it kept begging when full. Thus it would not be worth the predation risk to keep squawking when full.
Under what conditions do bird chicks beg louder?
- If this bird species shows extra-pair parentage, so brrod less closely related.
- If brood parasites are present.
In both of these examples, there is a lower risk of their relatives being eaten. - If they are a tree-nesting species.
Ground nesting birds shown to beg at a ——- frequency perhaps to be less hearable to predators than tree nesting ones.
higher
Why are sexual ornaments in bird species often honest signals of quality?
It is more costly for low quality males to show snazzy ornamentation. Thus it is only an affordable option for the high quality males.
How do certain toad calls give evidence of honest communication due to uncheatability?
Stuyd have shown that bigger toads of a species produce deeper calls, making them an honest signal for male size & ability deterring rivals.
How can species cheat honest communication of size, to an extent?
Inflating abdomen, puffing out chest, making hair stand on end, elongating larynx to make a deeper call.
Hamilton’s rule evolved around the idea of i—– fitness for a species. Under this rule, a behaviour was favoured if c<br.
What are the letters in this equation?
inclusive fitness
c= cost of behaviour to actor
b = benefit to recipient
r = relatedness
In Hamilton’s rule, what is an example of a positive c and b ?
Giving AWAY food
So STEALING food would therefore result in negative values
Under what 3 conditions can cannibalism in the Tiger Salamander evolve?
- Many members of species in population.
- Variation in larval size, so lots of small ones around to eat
- Mostly UNRELATED individuals.
Under Game Theory, why does the sex bias end up around 50:50 eventually?
It is of benefit to the parent that their offspring stand the best chance of producing grand-offspring.
They have the best chance of doing this if population has around a 1:1 sex ratio.
If a species can choose offsprings sex and there are lots of females currently, they may produce sons.
This would fluctuate, and overtime it’d be the best ESS for all broods to be around 50:50 between the sexes.
What does ESS stand for?
An Evolutionary Stable Strategy
Under Game Theory for sex ratios, what an i—– of a species is doing depends on what o—- members of the population are doing
individual, other
Definition: One indivdual directly interacting with another individual for a resource
Pairwise Contests. Thought up by John Maynard Smith
Hawk-dove interactions:
Hawks get …
Doves get …
all or nothing
less, or nothing when a hawk is there
Doves can win against hawks when c>v. What does this mean?
Doves can win against hawks when fighting cost is greater than the resource itself.
Hawks win against doves when v>v/2. What does this mean?
Hawks win against doves when resource to hawks is greater than the resource the doves get on their own.
What happens to the hawks and the doves if c>v and v>v/2 are both true at the same time?
We can get a mixed ESS
In the b—— strat within hawk-dove theory, an individual plays —– when it is the OWNER / RESIDENT of the resource but —- when it is an intruder
Bourgeois, hawk, dove
What are the 2 considered outcomes in rock-paper-scissors game theory?
- 1/3 of a population adopts each strategy
- Members of the popualtion cycle through each strategy, as demonstrated with male side-botched lizards of different morphs n mating strats.
John Maynard Smith introduced Pairwise Contests and he ALSO introduced the idea of o—– f—- theory, in which animals should ba;ance the benefits (energy) of getting a resource with the cost (time & effort) of adquiring it
optimal foraging theory
John Maynard Smith introduced Pairwise Contests and he ALSO introduced the idea of o—– f—- theory, in which animals should ba;ance the benefits (energy) of getting a resource with the cost (time & effort) of adquiring it
optimal foraging theory
What support did —- 1— find for optimal foraging?
Zach 1979 North-Western crows drop optimally sized whelks from the optimal height to get food.
Fill in these scenarios in which cost-benefit logic may NOT be met.
1. Animals — well adapted
2. Observations made were ——–
3. Important —— not considered in model
4. ——- were not valid
1.NOT
2. Innapropriate / unsuitable
3. Factors
4. Assumptions
How did oyster catchers show that an invalid assumption had been made under cost-benefit logic?
Oystercatchers initially predicted to go for largest mussel.
However, these cannot be opened.
Thus they went for an optimal size of 50mm instead.
Belovsky 1978. A classic study. What 3 constraints do moose need to balance?
Energy, rumen volume and sodium from food.
- Aquatic veg has high sodium and little energy.
- Trees have the opposite.
Thus moose eat both.
What does Charnov’s MVT stand for?
His Marginal Value Theorem
Which theory predicts that animals should LEAVE their current foragaing patch when the energy intake rate becomes lower than the average energy-harvesting rate.
The Marginal Value Theory
Why may energy returns from a food patch diminish after an individual has spent a certain amount of time there?
- Food may be depleted, or an animal gathering food for it’s young may be encumbered by the food it has already collected.
If you take a shorter/longer time to arrive at a patch, you should spend longer at it
LONGER time. Think of a strategically placed Big Aldi Shop
Kacelnik 1984 trained starlings to feed at different stations, showing that load size did / did not increase with distance from nest, in line with MVTs
DID increase
(Some) Assumptions of MVTs:
1. Travel time between patches IS —– by the species
2. Travel costs = patch costs… what if a species sits down to nibble?
3. Patch p———– is known by species
4. No ——
And more
- Is KNOWN
- Profitability
- Predation / effects of predation
In great tits (—– 1—) it was found that travel cost was ——- than the cost of being in that patch, thus not meeting the assumption of MVTs that travel cost=patch cost.
Cowie 1977 greater. Birds sat down to eat.
In (what) species found that they did minimized search costs and maximized energy intake, suggesting that the MVT assumption that patch profitability is known was true
Downy woodpecker
What can we do when optimal foraging models fail to predict observations?
- Ignore them
- Accept animal is sup-optimal (unlikely)
- Rebuild model
What are some benefits of oprimal foraging models (3)?
- Provide testable and quantitative predictions
- Make some explicit assumptions
- Illustrate GENERAL nature underlying animal decision making
Give 3 reasons why some behavioral traits are non-adaptive
Trait evolved in past conditions which dont exist today
Trait incidental side-effect of beneficial adaptation
Trait maladaptive consequence of a very recent change in the environment
What is the comparative method? Why is it used?
A method for testing evolutionary hypotheses by comparing different taxa to see who does what, and correlating trait occurrence with benefit
Used when not possible to compare trait presence within a species
Mobbing behaviour in gulls has been studied by comparing within species and by taking a c—— approach - looking & comparing phylogenies
comparative
Fill in the 4 main antipredator behaviours:
1. Anti-d——-
2. Anti-a——
3. Anti-c—–
4. Anti-c——
- Anti-detection
- Anti-attack- stotting
- Anti-capture- escaping
- Anti-consumption - feigning death / fighting etc.
Give an example of anti-detection
The decorator crab. May preferentially choose a special algae as it contains a repellent chemical for predatory fish
Some key points:
1. C—– may involve a– of the senses
2. Both p— and p—– may be camouflaged
camouflage, prey & predator
Caro 1986 - why stot?
Less stotters chased than none-stotters. Stotters never killed. Studied Thompson’s Gazelle
Why would selfish herding be advanteageous? Which study is cited?
May INCREASE total predation risk but DECREASE individual risk - Hamilton 1971
Selfish herding must OUTWEIGH increase in c——– to predator
conspicousness
To avoid predation, species may also show s—— so as to stand a better chance of s—– predators. Shown in mayflies, fish spawning and seabird egg laying.
Synchrony, satiating
As well as the dilution effect, selfish herding may also increase v——. Demonstrated in pigeons, where this was higher in larger groups.
vigilance
The trade-off between f—/ s—- and s—— herding is shown in Sparrows
food / safety, selfish
Define secondary sexual charecteristics
A character which distinguishes between the sexes but is not used for intercourse. Sexual dimorphism
What was the original basis for sexual selection?
Anisogamy between female and male gametes
Why do females (usually) choose a mate?
Limited by number of eggs/ offspring they can produce, leading males to compete instead.
There is a GREATER correlation between body size / antler size etc. in p——- species than m—–
polygynous, monogamous
Key points on sexual selection:
1. Sexual selection does NOT always lead to sexual d——-
2. Sexual dimorphism can arise from processes other than sexual s—— such as different sexes inhabiting different ecological niches
dimorphism, selection
A problem in identifying outcome of sexual selection is that it is hard to tell if it was due to m—-m— competition or f—– c—-. Must use experimental m—— to do this, such as on the widowbird
male-male, female choice, manipulation
Match these up:
1. Lower investment in offspring =
2. Higher investment in offspring =
3. Equal investment in offspring =
Both compete & choose, choice, competition
- Competition
- Choice
- Both compete & choose
Why do crested auklets BOTH show sexual selection?
Both invest heavily in offspring, thus both choose and select.
Mutual sexual selection is…
possible but quite rare - crested auklets as example
Give some examples (2) of sex role reversal, wherin male investment is higher
- Pipefish - they carry the babies
- Katydid insects - they produce massive spermatophores
What does OSR stand for?
The operational Sex Ratio
Explain WHY anisogamy evolved
A large embryo has a higher chance of surviving. Relationship is NOT linear however
Creating many small gametes, or a few large ones takes same amount of resources.
SMALL gametes stand better chance of fusing
HOWEVER 2 smalle gametes fusing is disadvantaegous.
Therefor, 2 gametes of the sexes diverge from eachother so they can only fuse successfully with other, different sized, gamete.
Definition: The competition between 2 or more male gametes within the reproductive tract of the female
Sperm competition. Post-copulation compeition
Fill in these 3 examples of sperm competition:
1. R—– sperm of rivals with an elaborate penis: Mayflies
2. P—— males producing more v— sperm than m—– males: Many insect species
3. Extra-p— c—–: Adelie penguins
4. P—— p——: Magpies guarding mates
Removing, polyandrous, viable, monogamous, pair, copulation, protecting paternity
How does much copulation in birds such as the Fulmar protect paternity?
Ensures the optimal timing of insemination relative to fertilization
DEFINITION: Female manipulation of the sperm of more than one male WITHIN her reproductive tract, allowing a chosen male to fertilize the egg
Cryptic Female Choice
How do some females carry out cryptic choice (2) ?
- Hens keep sperm in tubules in their tract. Can EJECT the sperm of suboridnate males from cloacas and ACCEPT the dominant ones.
In invertebrates, may also STOP copulation forcefully after her snack has been finished, such as in the hanging fly
How may a male bird try and prevent female choice?
Peck cloaca if other male has been near to force her to eject sperm
Why do females engage in CFC? 2 reasons
- Get higher quality offspring
- Get more offspring from a more compatible mate
Give the 2 types of mating strategies for males which lose:
- Equally rewarding, such as beta isopods living with other betas and an alpha. Betas mimic females, and alpha fight. Gamm hide.
- Unequally rewarding, such as the medium and small males in scorpion flies, which try and force copulations, or give shitty nuptial gifts from their saliva
What did the Albo et al. 2013 paper study?
Female Cryptic Choice in Nursery Web Spiders.
Found that better nuptial gifts increased
1. Mating
2. Sperm storage by females
Nuptial gifts also got higher egg-hatchy success, even under equal copulation length.
Nuptial gift under positive selection by females.
Experiment controlled for copulation length & made it the same for with / without nuptial gifts
What did Pryke et al. 2017 study? Which bird? Why?
The Gouldian Finch
It has 3 colour morphs, and sexes are more compatible with the same colour morph as them
They participate in extra-pair copulation, which the females allow more when male is same colour.
Female can manipulate sperm in tract, thus more eggs fertilized from compatible males.
Shows role of CFC and benefits of extra-pair copulations to females too
In the female adelie penguin, e—– must be drawn in for insemination to occur
ejaculate
What are the 2 sources of sperm competition in the adelie penguin?
EPCs and mate switching
Why did female adelies engage in prostitution (3) ?
- Gained good nest materials (STONES), good genes (sexy sons?) and fertility assurance
How can male Adelies fail at insemination?
They may fall off or not finish. Their sperm may also get dislodged. They may run out of ejaculat
In what two ways can male Adelies cope with running out of ejaculate? How do they do this?
- Keep copulating anyway.
- Staretgically allocate matings
- They strategically allocate the matings to EPCs by withholding ejaculates from their partner
Why do male Adelies participate in EPCs when pair males father the vast majority of their offspring?
Benefits so high it makes it worthwhile, and additionally some of the fathers may be infertile anyways.
What 4 things does a mating system include?
Copulation behaviour
Social organisation
Parental care
Competition
What are the four main mating systems?
Polgyny
Mongamy
Polyandry
Promiscuity . polygynandry (everything all at once)
Species can show multiply of these systems at once, such as the dunnocks.
Males are limited primarily by ——- and females are limited primarily by ——. Demonstrated in G— V—-. Males follow females. Females do not follow males.
females, resources. Grey Voles
Female m—— by males depends on:
1. Female g—- s—
2. Female r—– s—
group size, range size.
What may a male (eg. an orangutan) do when he has a large range size?
Assosciate with fertile females by following them around in his territory
Female social groups can have a d—— range in small (colobus monkey) and large groups (lions).
A large range may NOT be d—– for large u—- groups like topi, resulting in behaviour like l—–
defendable defendable, lekking
Evidence has shown that when the female range is very small/big male range is very small/big
big, small.
How may males attract females to them for once (2)?
By controlling a resource she likes, such as tent-making bats making little leaf tents, wherin the bigger tents are the better.
They can also show parental care.
Males may ‘prefer’ p—— wheras females may ‘prefer’ p——, leading to conflict over the mating systems.
Polygyny, polyandry.
An example of this is marmots, wherin females prefer small groups to raise offspring, and males prefer large groups to raise them.
What taxa is cooperative breeding mainly seen in ? Give examples of species which use cooperative breeding
Insects. Also seen in some birds and a few animals. Examples-
- Florida scrub jay
- Silver-backed jackal
- Naked mole ratsa
Definition: P—- B——- Several males n females sharing a nest to raise a communal brood. Shown in banded mongoose, and acorn woodpecker
Plural breeders
Explain the ecological constraints hypothesis. There are 3 steps
- independent breeding is constrained, perhaps due to habitat satuaration or ecological constraints
- grown offspring thus delay dispersal and stay at home. The fitness benefits of helping exceed that of not helping
- grown offspring help to rear later broods
What are some direct benefits of cooperative breeding (3)? Includes g—- a——- h——–
- less predation
group augementation hypothesis: bigger group, more benefit to current and future reproduction / survival thus cooperative breeding is favoured - direct reproduction ie. by sneaky egg laying
give experimental support of the group augementation hypothesis
banded mongoose kidnapping other members to join their groups
What is the increased experience / skills hypothesis? What species gives us an example of this? s——- w——
Breeders who helped in past have more breeding success. Shown in seychelles warbler. HOWEVER hard to tell if this is a benefit of cooperative breeding or the breeding pairs just ‘being better’
Give some indirect benefits of cooperative breeding (2). Give examples.
- increased reproductive success of relatives as shown in long-tailed tit and white-fronted bee-eaters wherin more helpers produce more fledglings. Birds reproducing may just have more experience anyways tho and may not be down to cooperation :(
- increased survival of related breeders
What is strange about the ECH for cooperative breeding?
Some species face these constraints but still do not demonstrate cooperative breeding
Which one out of ants, bees and wasps is only ever eusocial?
Ants
What are Homoptera? Are they eusocial?
They are aphids which show some eusocial characteristics, such as some cooperative brood care, some non-reproducing individuals and an element of specialized roles. Don’t have elaborate caste systems however
What are Isoptera?
Termites. Most species eusocial
Give the three key features of eusociality
- Cooperative brood care
- Sterile castes
- Overlapping generations - offspring do not leave
Eusociality is ecologically important as it can be so a——. How can colonies like insects get so large?
abundant. Able to get this large because of sophisticated communication (pheremone trails, waggle dance…)
How do sterile castes benefit a colony?
Sterility means that energy meant for repro to be used towards extreme specialisation instead
What is the general 4 stage lifecycle of a lot of eusocial insect?
queen founds nest –> production of sterile female workers –> production of winged females n males ~ 9 years later –> nuptial flught and REPEAT
What is the subsocial hypothesis for eusociality?
Some offspring do no disperse and remain to help female guard nest o reduce predation / parasitism risk. Eventually these young evolve to never breed. Benefits breeder as she is more related to her own offspring than if they were to go off and have grandchildren
What is the parasocial hypothesis for eusociality?
Sisters buils nest close together and have cooperative defence but seperate reproduction. One female eventually dominates reproduction & the young females become workers
How does relatedness predispose eusociality to evolve?
Relatedness of offspring to parent and sibling to sibling is both 0.5. Grandchildren to grandparent would be just 0.25, thus parents benefit from children staying and not reproducing
Which sex is which in eusociality?
1. develop from unfertilised egg so genetically identical - h——
2. develop from fertilised egg so show variation - d——
- Male, haploid
- Female, diploid
In eusocial ANTS, sister and brother have a relatedness of 0.– (0.50.5 + 0.50.0) (maths = bit of DNA females get from mum multiplied by bit of DNA males get from mum)
and sister to sister has a relatedness of 0.– ( 0.50.5+0.51). This is as fathers give ALL their haploid DNA to offspring and females just give HALF (0.5*1)
0.25
0.75
As sisters are more related to eachother than to their brothers it thus…
Makes sense for workers to be female and help eachother out
how are termites and aphids workers different in terms of relatedness?
Termites: Males and females equally related to siblings and both sexes become sterile workers
Clonal aphids: All clones
How is the sex ratio in conflict in ant colonies?
Queen wants an even ratio as sons n daughters equally related to her, but workers want yet more sisters.
So, who wins this conflict?
Would think the queen would win because she fertilises the eggs, she can choose between creating sons or daughters. She just has to fertilise half the eggs to create the ratio (rememebr she stores the sperm, thats why she has that control)
However, workers could neglect looking after males and prefer females to change sex ratio
Give an example of intraspecific vs interspecific brood parasitism
Intra: Starlings throwing out eggs of other parent n replacing it. Hard to tell when this happens
Inter: Cuckoo catfish laying eggs in cichlid fish clutch. Cuckoo hatches early in cichlid’s mouth n devours it’s own offspring
Give some natural history traits of the cuckoo (6)
- Lay fast
-Lay more eggs than normal - Remove host egg
- Lay small egg
- Lay in afternoon
- Mimic specific bird species - 1 species per ‘gen’
D—- and B—- 1—- investigated cuckoos with model eggs. What did they find? Tested mimetics, speed, timing etc.
Davies & Brooke 1988
Model egg always rejected if placed in before host lays.
Model egg more than ½ accepted if put in nest in morning, and not in afternoon.
Why lay so fast? 45% of eggs rejected when stuffed cuckoo placed beside nest
Why lay small egg? Large egg much more rejected
Why lay mimetic eggs? Much more rejected if eggs are of different gens
Rejection of cuckoo egg by host happens more in…
s—– areas
p—— species
When a parasite is introduced to an area, there can be an arms race between the evolution of m—– by the parasiyte and the hosts d——. When the hosts defences ‘win’, they may unfortunately weaken again as there are no hosts, thus the cycle continues
sympatric, parasitised, mimicry, defences
Evolutionary arms race in (what species) showed that nest parasite t—– the hosts eggs p——- overtime
Prinia bird. Based on big collection of birds eggs over decades.
tracked, phenotypes
Give 3 reasons why mimicry and defences may vary across bird species
Rejection due to error is costly
Ejection of egg could damage own eggs
Hosts may evolve other defences like nest defences
What is selfish herding studied in?
Whirligig beatles
