Behaviour and adaptation Flashcards
proximate vs ultimate explanation
- define
proximate = immediate explanation for a behaviour
ultimate = evolutionary significance of a behaviour
proximate vs ultimate explanations
- inbreeding avoidance
proximate
= general behaviour that avoids inbreeding
e.g. don’t mate with those you shared a nest with
ultimate
= avoid deleterious recessive phenotypes
why do orgs avoid inbreeding?
avoids combinations of deleterious alleles
- need to produce successful offspring that can pass on genes
hunting example
- facts
cheetahs hunting impala
C short bursts of up to 100km/hr
I top speed ~60km/hr
only 10% cheetah hunts successful due to short bursts and not as agile
hunting example
- selection predictions
- why?
should favour high speed in BOTH cheetah + impala
fastest cheetah should have highest fitness
slowest impala should have lowest fitness
hunting example
- why might we NOT see these predictions?
no variation in traits
- e.g. all run at same speed
variable running speed but NO heritable component
- determined by enviro = not affected by selection
speed may not be main component to success
- e.g. stealth + agility needed to chase zig zagging prey
trade offs
- fastest cheetahs exhausted after hunt = more vulnerable to predators
coloniality
- facts
many birds breed in colonies
- can be up to 1M in 1 colony
can reach high densities <40nests/m2
coloniality
- hypotheses for why
protection from predators
increased foraging success
coloniality example
- Black-headed gulls
protect the colony from crows
- nests inside colony protected more than those on outside
correlation suggests higher probability of a crow being attacked by a gull inside the colony
-> lower % of successful predation
coloniality
- predators
- prediction
colonies attract predators
- some colonies more vulnerable than others
depending on the enviro, will be susceptible to different predators
exposure to predators influences egg camouflage and the behaviour of adults + chicks
coloniality predator example
- nests
exposed nests e.g. black-headed gull on ground
- camouflaged eggs
- eggs shaped to maximise incubation efficiency
protected nests e.g. bald eagle on steep cliffs etc.
- eggs not camouflaged
- eggs shaped to not fall out nest
coloniality predator example
- chicks
exposed chicks
- camouflaged
- wander around nest
protected chicks
- not camouflaged
- stay in nest
coloniality predator example
- adults
exposed nests
- remove egg shells immediately after hatch
protected nests
- egg shells NOT removed immediately
why are egg shells removed by parents?
white inner of eggs makes nest conspicuous
= attracts predators
phylogenetic inertia
- define
- how does this affect taxa?
if your ancestors had a trait
-> likely you will too
related taxa likely to have similar traits due to phylogenetic inertia
.:. those taxa aren’t independent observations of the trait
phylogenetic comparative methods
- what is it?
- what do they do?
statistically analysing a trait that’s evolved multiple times
take into account the relationship between taxa
only uses independent contrasts
independent contrasts
each time a trait changes in a tree
= creates 1 comparison
(no. of species is irrelevant)
penis fencing in flatworms
unilateral transfer of sperm
- they keep fencing until inseminated
some species store sperm for several rounds before laying eggs
paternal care in marine snail
- what happens?
after copulation, females deposit their egg cases on shell of the male they last mated with
male cares for eggs until they hatch
paternal care in marine snail
- why is this costly?
males carry eggs for <1 month
egg mass = ~40% of avg male mass
so males lose weight
some eggs sired by other males
- cannot dislodge these without killing his own
paternal care in marine snail
- why does this persist?
> reciprocal benefit
- other males carry his
> may assist own offspring
- cannibalistic embryos
- could boost their offspring’s viability by secreting or choosing favourable enviro
> may be best strategy is finding mate is hard
(pop density or sex ratio)
- better to care for other male’s young than get no paternity
siblicide in blue-footed boobies
siblings fight aggressively over food
- maybe to death
- > get resources from parents
eggs are layered asynchronously
-> older chick kills younger
sometimes aligned
- if not enough food, don’t have to waste resources on weaker offspring
infanticide in lions
males taking over pride kill all cubs below critical age
- > brings females in oestrous sooner
- > males get cubs sooner + increases reproductive success
Tinbergen’s 4 questions
function (adaptation)
phylogeny
(evolution)
mechanism
(causation)
ontogeny
(development)
why do birds sing?
- Tinbergen’s 4 questions
- -> mechanism + function
mechanism
= changes in day length + hormone levels
function = males sing to attract mates + breed
why do birds sing?
- Tinbergen’s 4 questions
- -> ontogeny + phylogeny
ontogeny
= male robin chicks learn the song from adults (often fathers)
phylogeny
= robins inherited this behaviour from ancestors
why do birds sing?
- Tinbergen’s 4 questions
- -> which is correct?
all correct
different ways of asking questions about the behaviour
bird song
- used in 2 main contexts
- how many birds use it?
mate choice
territorial defence
~4000
bird song
- learned from father experiment
compared sound frequency of father’s song to sons with intact or no hearing
deaf son had completely different song to father
song development
song learning + production are coordinated by a group of brain nuclei
(= the song system)
song development
- impaired learning system
birds produce song but can’t learn new syllables
song development
- imparted producing system
birds can learn song but can’t produce the song
neurobiology of song
brain nuclei involved in song are distinctive
= RA = robust nucleus of the arcopallium
males have larger song nuclei
size of nuclei varies over year
- large in breeding season + small in non-breeding season
song and territory acquisition
territories with complex song are occupied later
the more songs you have, the longer you stay in the better territory
song and mate choice
males with larger song repertoire mate sooner
