3.1 population connectivity & hybridization

species and populations

• species → interbreed in nature and produce fertile, viable offspring

• population → group of individuals in the same species living in the same area

gene flow

• individuals emigrating from one population and immigrat to another populations

  • alleles transferred

• alleles → gene variations

genetic drift

• chance events that cause allele frequencies to fluctuate from one generation to the next

• usually with small populations

founder effect

• few individuals isolated from a larger population and establish new

  • new pop may have different genetic diversity than source

bottleneck effect

• severe drop in population size

• alleles may become over/underrepresented

• other side of bottleneck can have low genetic diversity

hybridization

• mating of individuals from two species w/ incomplete reproductive barriers

• gene flow between species

hybrid zone

• overlap in population ranges of different species allowing hybrids

reinforcement

• strengthen repro barriers

• hybrids less fit than parents

• fewer hybrids formed

fusion

• weakening of reproductive barriers

• gene flow increases over time

• two species may fuse back into one

stability

• few hybrids produced every season

• same number produced over time