Genetic Diversity

Genetic Changes in Populations

• Selection

• Migration

• Randon chande (genetic drift)

• Mutation (generally slow)

Selection

• Natural selection

  • Organisms of different genotypes contribute differently to the gene pool

  • Genotype: specific genetic information possessed by an individual

  • Gene pool: All genetic variants present in all individuals in a population

• Artificial selection

  • Humans choose the parents of each generation based upon traits they want

  • Hatchery-produced steelhead that did well in the hatchery had low reproductive success in the wild

Migration

• Adds new genetic variants to a population

• Can reduce the effects of inbreeding (genetic rescue)

• Can threaten the genetic integrity of a population

• Outbreeding depression

  • Ibex

    • Introduced desert-adapted animals of a different species subspecies

    • Hybrids gave birth in Feb (coldest month of the year)

    • Population went extinct

  • Largemouth bass

    • Moderate population differentiation

    • Hybrids- increased infectious disease susceptibility

Genetic Drift

• Random changes in allele frequencies

• Allele: variants of a gene

• Gene: Segment of DNA that codes for a particular trait

• Bottlenecks, founder effects