2.5: Agents of Evolutionary Change - Gene Flow

gene flow

describes spread of genetic variation across geographical areas due to migration, hybridisation or gamete dispersal

requirements for gene flow to occur

individuals must be able to disperse, interbreed and produce viable offspring

what does the impact of gene flow depend on

• genetic difference between populations

• level of migration, movement or hybridisation (m)

if frequency of alleles are the same any gene flow won’t be detected = doesn’t affect evolution. If allele frequencies are different the gene flow will be effective. Level of movement/etc effects flow = the larger it is the faster the frequency of alleles changes in resident pop

resident population

a population that remains in a specific geographic area and is affected by inputs from migrant individuals.

formula for estimating gene frequency changes in residents

Δp = m(f(x)migrants - f(x)residents)

• e.g. m= 5% per gen, migrant f(x) = 0.6 and resident f(x) = 0.4. Δp = 0.05(0.6-0.4) = 0.01. This means that the first gen of migration would go from 0.4 to 0.41

what happens when m = 1 or 0

m = 1 - resident population would be completely overtaken by migrants

m = 0 - there would be no migration

does gene flow always require migration

yes