Lecture 13 - Genes, Environment, and Behaviour

proximate causes

how/what? questions

• how does an individual manage to carry out an activity?

• how do mechanisms within an animal work to produce a particular trait?

ultimate causes

why? questions

• why has that particular trait evolved?

ultimate cause questions regarding behaviour

why has this behavior evolved and how has it changed over evolutionary time?

proximate cause questions regarding behaviour

what is the causal relationship between the organism’s genes and its behaviour

bees proximate cause for behaviour

their drunken behavior in the fall is a reaction to ethanol (what?)

bees and wasps are feeding on overripe fruit (how?)

bees ultimate cause for behaviour?

attraction to alcohol is an adaptation they developed to be better at finding ripe fruit cause overly fermented fruit produce the alcoholic odor

what do phenotypes reflect?

they reflect the individual genetic and environmental effects as well as the gene by environment interaction

how are we able to tell identical twins apart?

even though they have the same genes differences are observed due to differences in their individual environmental intearctions

polymorphism

when there are two or more possibilities of a trait on a gene

fruit fly development

lays eggs on fruit then larva emerges and eats the fruit in order to develop into an adult

within food patch behaviour differences in the foraging gene

rovers move way more than sitters

foraging gene behavioral differences in the absence of food

rovers and sitters both move more often and for similar distances

what causes the difference in the foraging gene (rover vs sitter)?

a single nucleotide polymorphism in the pr4 region of the foraging gene

which foraging allele has higher gene expression?

the sitter gene

rover allele

dominant

sitter allele

recessive

rover costs and benefits

they can find more food but they have to expend more energy looking for food

what are the requirements for evolution by natural selection?

requires variation in a trait, a genetic basis for the trait and variation in fitness for the trait

how were the environmental effects of foraging evaluated?

the adults were deprived of food for either 4 or 24hrs then assayed for foraging behaviour

foraging environmental effects results

reover traveled more than the sitter in both condition and movement was significantly reduced at 24hrs compared to 4hrs for both the rover and the sitter

plasticity

an environmental effect on the phenotype of a single individual or genetically identical individuals

reaction norm

describes the effect of some environmental variable on the phenotype of a single genotype

reaction norm for no slope

only genetic difference are observed

what is the morphological response to predators observed in Daphnia

their helmet size gets bigger the more predators are in the environment

phototactic behaviour in daphnia

they are attracted or repelled by light in response to predator activity (adaptive behaviour)

evolution of reaction norms in daphnia

if they have a selective history of predation risk they have evolved to avoid habitats with high risk of predation

what shapes the reaction norm?

natural selection