Genetic theory of natural selection Flashcards
With drift, ______ alleles tend to be _________
RARER ALLELES TEND TO BE LOST
What are the three mods of selection
- directional
- stabilizing
- diversifying
What is directional selection>
- phenotypic frequency is pushed towards more extreme value of the trait, rather than the average
- bell curve shifted right or left
what is stabilizing selection
- phenotypes are stabilized, against rare/extreme phenotypes
- favoring intermediate phenotypes over both extremes
What is diversifying / disruptive selection
- selection AGAINST the average, extreme phenotypes are favored
the more genes influencing a trait, means a more….
continuous variation across a population
what is an example of directional selection?
- Darwins finches
- beak depth in the medium ground finch
- strongest beaks passed trait onto offspring
what is an example of disruptive selection?
- niche partitioning
- soapberry bugs beaks, small and long beaks best for different types of fruit
reproductive success is ….
the number of offspring born and also those that survive
absolute fitness is
per capita growth rate of that genotype, number of offspring produced over a life time
relative fitness (w) is
a genotypes population growth rate to that of a reference genotype (the genotype with the highest growth rate)
mean fitness (W) is..
average fitness of individuals relative to fittest group
what are the four components of selection is sexually reproducing species?
- viability
- mating success
- fecundity
- fertilization success
What is viability?
probability of survival thru reproductive age
What is fecundity?
ability to produce abundant offspring (fertility)
average number of viable gametes per female
what is coefficient of selection (s)?
- measure of the strength of selection that ‘favours’ the allele of interest
- s=0 no selection
s>1 = selection is favouring a particular allele
the rate of evolution is a population depends on two things……
- strength of selection
- amount of genetic variation
