Population Structure Flashcards
What determines the genetic structure of the population
History- geography
Ecology- resources avaliable, climate
Why do species differe in morphology depending on geography
Genetic causes
Mutation, genetic drift (stochastic), natural selection –> adaptations
Divergence and differentiation
Dependent on the specific population
Increased population size –> genetic drift has left effect, increased variation due to mutations
Gene flow –> homogenising of populations
Founder effects
What affects gene flow and what are its effects
Geography- islands are less likely to have visiting populations which spread genetics and have increased likelihood of endemics.
Gene flow constrains evolution because it prevents adaptation to a specific niche, however it promotes evolution due to spread of genes
What is the founder effect
Small number of individuals colonise an area
Small number of individuals only have a limited amount of variation –> more vulnerable
Obesity in TONGA- people with slow metabolisms survived journey but now struggle with western diet
Drosophila in Hawii
What is clinal variation
Gradient of traits caused by variation produced during a changing environment?
E.g. hermanns tortoise- 2 sub species READ PAPER
Why is there so much debate about the phylogeny of the hermanns tortoise
1 sub species has a large amount of variation in morphology but the other has very little.
One sub-species is more widespread than the other
Mallorcan tortoise is very similar to that found in Formentera, Spain and Italy
No evidence for them being different species, geography and morphology may vary due to human interaction.
