Behaviour and adaptation Flashcards
(35 cards)
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)
