7.3 Environmental selection pressures, genetic drift and genetic flow

environmental selection pressures

external agents which influence the ability of an individual to survive in their environment

selective advantage

relative higher genetic fitness of a phenotype compared with other phenotypes controlled by the same gene

natural selection

process in which organisms better adapted for an environment are more likely to pass on their genes to the next generation

genetic drift

random changes, unpredictable in direction, in alleles frequencies from one generation to teh next owing to the action of chance events

bottleneck effect

chance effects on allele frequencies in a population as a result of a major reduction in population size

founder effect

chance effects on allele frequencies in a population that is formed from a small unrepresentative sample of a larger population

gene flow

the movement of individuals and their genetic material between populations

immigration

the movement of individuals and their alleles into a population, and thus into a gene pool

emigration

the movement of individuals and their alleles out of a population, and thus out of a gene pool