Selection And Polymorphism Flashcards
What mode of selection favours the extremes?
Diversifying
Name the 3 modes of selection
Diversifying
Stabilising
Directional
Stabilising selection does what?
Acts against the extremes
Directional selection causes shifts in what direction?
Any but the whole population shifts to favour that extreme
Strength of selection can be positive or negative, true or false?
True, above 0 = positive, below 0= negative
If intermediates are selected for, what mode of selection is taking place?
Diversifying
Diversifying selection results in what?
Multi niche polymorphism
What drives polymorphism?
Habitat generally
How is polymorphism retained?
- Diploidy
- Gene flow
- Mutation
- Balancing selection
If an allele is recessive it is never selected for or against and the more rare the allele, the more hidden it is
Diploidy helping to retain polymorphism
Gene flow could allow intermediates to be selected for..how?
Move to a new environment am that isn’t selected for so all the alleles will be
Heterozygote advantage is an example of …
Balancing selection as 1 copy of the allele promotes better fitness than a homozygote
Adaptation can promote
Variation
Heterozygote advantage includes:
Population load
Heterosis
Duplication instability
Positive frequency dependent selection can …
Increase fitness in bigger populations
