Week 8: Landscape Genomics, Behvaioural Ecology Flashcards
What are metapopulations?
a group of populations linked by dispersal and gene flow
- exist in balance of extinction and recolonization
Why might snake species with different foraging strategies have different genetic differentiation?
- ambush predators don’t move around, more isolation by distance
- active hunters are moving/mixing, less IBD, IBR
What do we look for when finding isolation by Environment (IBE)? Why?
local adaptation!
(outlier loci)
- Genetic drift is random, selection is not!
What are outlier loci and why are they useful?
when one allele is more common or less common than other alleles (Fst values between two subpopulations), it shows there is different selection between sites!
How were SNP data used to find evidence of natural selection in Yucatan Jays?
- IBD in neutral SNPs
- IBE in functional SNPs: outlier loci related to temperature and precipitation
In what 3 ways can selection be measured?
- outlier loci
- fitness of traits
- quantitative traits
What is the selection coefficient (s)?
the strength of selection
- traits are compared to the trait with the highest fitness
What does it mean if light-coloured moths have s=0.32 compared to dark-coloured moths?
the survival odds of light moths are 32% lower than that of dark moths
What determines fitness
reproductive success
What does it mean if the relative fitness (w) of light moths is 0.68 compared to dark moths?
for every 100 dark moths that survive, 68 light moths will survive
What three factors influence population differentiation?
- genetic drift
- gene flow
- adaptation (natural selection)
What factor influences the strength of genetic drift?
Ne
(effective population size)
What factor influences the strength of gene flow?
dispersal
(connectivity of subpopulations)
What factor influences the strength of adaptation?
s, the selection coefficient
(strength of selection)
In population differentiation, what is the relationship between gene flow, genetic drift, and local adaptation?
- gene flow is homogenizing
- drift and adaptation are differentiating forces
What effect does gene flow have on genetic drift and local adaptation?
- more gene flow reduces genetic drift (higher Ne)
- more gene flow might slow adaptation, if selection pressure is low enough
Why is coat colour selected for in deer mice, and why aren’t they all the same colour?
colour gives camouflage from predators, but variation still exists because the environment is variable!
How can selection be a barrier to gene flow?
even if lots of individuals disperse, if they aren’t suited to that environment their alleles will not survive
When can gene flow counteract selection?
when dispersal is stronger than the strength of selection (s)
How do we predict whether drift is stronger than selection
- If s >1/(4Ne) –> weak drift
- If s<1/(4Ne) –> strong drift
What is the first question to ask when determining the causes of differentiation between subpopulations?
Does the population have an appreciable amount gene flow?
What is behavioural ecology?
how behavioural interactions increase fitness
What behaviours has ecological genetics helped understand?
- mating behaviour
- dispersal behaviour
- foraging behaviour
What is the difference between polygyndandry and promiscuity?
- poplygynandry involves social bonds
- promiscuity does not involve social bonds
