lecture 5 - natural selection Flashcards
what is purifying selection?
an allele that everyone has - it is core for survival
what is stabilizing selection?
continuous trait e.g. height – where the most beneficial trait is around the mean for the pop – mean height, expect ppl who are very short or tall have lower reproductive success
what is directional selection?
causes evolutionary
change - builds adaptations
what does ‘evolution is blind’ mean?
evolution builds complex adaptations w/o any planning – does it through a non random retention – it acts in v small steps with small processes
what is a time lag?
selection takes a long time – if its not costly then it may leave it for longer e.g. the whales pelvis which it doesn’t need as it has no legs but it isn’t costly so they haven’t got rid of it yet
what is inconsistent selection?
selective environments can vary e.g. grasshoppers - their environments change so they can go green and black so that they can camouflage - this happens as they grow and malt - this doesn’t happen at once
what are genetic correlations?
most genes have an effect on more than one trait (plyertropy) - therefore, these traits are correlated
what is an example of a genetic correlation?
silver foxes - one group was randomly bred and another were selected for being tame - those that were tame got tamer than the control and also had other changes e.g. curly tails, floppy ears etc
- the gene that controls tameness also controls these traits
what is the adaptationist stance?
assume if an animal looks or behs in a certain way – we assume this is the optimal way to behave
- We can do manipulative experiments, experiments of nature – you just take the recordings, comparative evidence – we can make comparisons between closely related species
why may selection not produce optimal outcomes?
time lags, genetic correlations and local adaptive peaks
what is reverse engineering?
melanin absorbs UV light
Diffs in skin colour as this critical window differs due to environmental factors – if lots of uv light then may have darker skin as they need the protection more
if we cant compare pops from diff places who can we compare?
ppl of diff descents as they have diff melanin and backgrounds but the same enviroment
what did the study on vitamin D of women from African and European descent show?
vit d deficiency is more in women of African descent and skin damage is more common with those from european descent
what does high skin reflectance mean?
pale
what does low skin reflectance mean?
dark skin
when looking into prosocial beh in primates what did we expect the monkeys to do?
if you are being watched you are more likely to behave prosocially and not steal peoples food etc
how was the prosocial beh applied to humans and what was found?
Had to pay certain price for coffee, milk etc and where it stated the prices, they would have images of flowers or images of eyes and would alternate
Eye – people paid sig more than when there were flowers
when are predators more likely to attack prey?
if they are looking in a diff direction – if looking straight at them, took longer to attack them
