Function of behaviour Flashcards
What do functional questions ask?
Functional questions examine behaviour in terms of survival value or reproductive success.
These relate to fitness.
The ultimate factor behind the evolution of behaviour.
What is the function of nuptial gifts in hanging flies?
Male attracts the females by offering the nuptial gift and whilst the female is eating he can mate with her and therefore increase his fitness.
There is a linear relationship with the size of the nuptial gift and the mating time which plateaus somewhere between 15-20 min.
An increase in duration of copulation (mating) also increases the number of sperm transferred until about 20 min
Function and currencies
Fitness is very hard to measure.
Behavioural ecologists usually examine currencies related to inclusive fitness.
Survivorship, reproductive success, rate of energy intake, etc.
So, behavioural ecology is mainly about food, sex and staying alive long enough to enjoy them.
Avoiding being eaten (behaviour)
Being sensitive of predators is likely to increase survival and increase the amount of time for mating and therefore increase fitness.
Wildebeest can’t have anti-predator behaviour all the time especially not when they are eating and looking down so wildebeest increase vigilance and aggregate in response to lion roars.
Avoiding being eaten – camouflage
Historical change in proportions of light and melanistic forms of Biston betularia.
Industrial melanism near cities with pollution.
Tree bark and lichen darker.
But habitat choice is important for camouflage to work as well just genetic factors.
Moths are not random in terms of where they settle
studies have also shown that moths choose more than just colours, they also spend a lot of time orientating their bodies to match the patterns of the bark.
Signalling to avoid predation (stotting springbok)
Some deer and antelope species jump into the air while fleeing from a predator.
This makes them more visible and uses up time and energy.
Why do this rather that running away as fast as possible?
Stotting is an honest signal to the predator.
An index of condition and escape capability, indicating to the predator that the prey is very fit and could easily escape.
What are the decisions foraging animals need to make
Where to eat:
Locating patches of food
Predator avoidance
What to eat:
Prey choice
Balanced diet
Finding food (honey bees)
Waggle dance of honey bees informs other hive members of the distance and direction to food.
the longer the central axis of waging the further away the food is.
The success of one individual is related to the success of all the other individuals as they are all very closely related (clones of each other) so they are all working together to increase all of their fitness.
Economics of prey choice (shore crab)
Why do shore crabs choose intermediate sized mussels?
Big ones have more flesh but normally they choose the intermediate sizes
maybe there is no choice and they are just more likely to eat medium size ones however in the lab the food source is artificially controlled.
The energy is hidden inside the shell so larger shells are harder to break in.
the profitability is measured in joules per second. So even if big muscles contain more energy they require more time to eat and open them up so its not worth it.
Does economics of prey happen in the real world as well as the lab
Ravens near the coast, these birds are getting hard shell prey such as muscles, to break the shells they drop them from a height on the rocks and then swooping down to eat the food. They are investing time and energy in this therefore it’s better for them to choose a certain height that’s not too and they only have to drop it from a height that allows for a small amount of repeats of dropping. The shells never break first time
Reproductive tactics males vs females
Females and males have different tactics for maximising their fitness.
Sexual conflict is partly due to anisogamy.
Anisogamy
Males and females are defined by the size of the gametes they produce.
Male gametes small, cheap, and produced in millions.
Female gametes large, relatively expensive and fewer in number.
What are the male tactics?
Mate with as many females as possible to fertilize the maximum number of ova.
Males often are less choosy selecting mates.
Sperm is cheap and seldom a limiting factor.
But male–male competition can be extreme.
What are female tactics?
Females should be choosy and mate only with high quality males.
Eggs are costly and in limited supply.
Female reproductive success is limited by the quality of offspring.
Criteria of female choice and give an example
Bigger is better!
Large male body size.
Bright male colouration.
Elaborate male ornaments.
Signals of male quality
Good genes.
Resource holding potential.
Parasite resistance.
Health.
Experimental removal of peacock eyespots leads to reduced attractiveness to females.
Optimal clutch size
Birds lay a clutch size that maximises their number of surviving offspring.
great tits
The maximum number of eggs they can lay is 14 but the optimum egg count is 7-8 because theis majorly influences reproductive success as these birds won’t be able to feed and care for too many offspring and so overall fitness is decreased
