Population genetics and natural selection Flashcards
What is the Hardy-Weinberg equation
P + q = 1
P =dominant) (q=recessive
What do we use the Hardy-Weinberg equation for
To predict the genotypes in a population
What can change allele frequencies
Non-random mating Random genetic drift Bottleneck effect Founder effect Natural selection Gene flow or Migration Mutation
Explain random genetic drift
A random change in allele frequencies due to sampling error over generations (which individuals mate/leave offspring - luck)
What size population do we see effects of genetic drift
It is evident in small populations
Explain genetic bottle neck
Population is reduced due to a random event. Can completely get rid of an allele. This reduces the genetic diversity of a population.
Explain founder effect
Individuals of a population establish a new population. Reduces genetic diversity as only few alleles are present from the original population (dependant on alleles of founders)
What are the three types of selection caused by natural selection
Stabilising
Directional
Disruptive
Explain stabilising selection
Natural selection favours the median. The peak gets higher an narrower but mean doesn’t change
Explain directional selection
Natural selection favours larger or smaller individuals(only one). Peak and mean shift to the side (extreme)
Explain disruptive selection
Natural selection favours the extremes of a population. Forms twin peaks.
What is frequency dependant selection
The success of individuals depends on the frequency of individuals with the specific traits and therefore so does the type of spread.
What is a cline
The gradual change in genetic/phenotypic composition
Explain mutation
Very slow. Usually disadvantageous. Role usually of Macroevolutionary proportions
Explain migration
When an individual moves from one population to another and successfully mates, adding to the gene pool.
