selection

Question 1

what is natural selection

Answer 1

individuals vary. mutations take place
some are better adapted for survival so are more likely to reproduce and pass on alleles
over time the frequency of advantageous alleles increases in the population

Question 2

whats directional selection

Answer 2

when there is an environmental change. selective pressure for species to change and respond to it in a certain way. favours individuals with different alleles.

Question 3

what is stabilising selection

Answer 3

when there is no change in the environment it remains stable. individuals with the phenotype closest to the mean are favoured for. individuals with extreme phenotypes are selected against reducing the frequency of the allele within the population. distribution curves become narrower

Question 4

distribution curves with selection

Answer 4

directional selection individuals at one extreme of range are selected for. individuals selected against at other side of range. there is a shift in the mean