Population Structure

Question 1

What determines the genetic structure of the population

Answer 1

History- geography

Ecology- resources avaliable, climate

Question 2

Why do species differe in morphology depending on geography

Answer 2

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

Question 3

What affects gene flow and what are its effects

Answer 3

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

Question 4

What is the founder effect

Answer 4

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

Question 5

What is clinal variation

Answer 5

Gradient of traits caused by variation produced during a changing environment?

E.g. hermanns tortoise- 2 sub species READ PAPER

Question 6

Why is there so much debate about the phylogeny of the hermanns tortoise

Answer 6

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.