speciation

gene pool - genes of each person in population

mutation - variation in gene pool

gene flow- movement of alleles between populations

CHANGE FREQUENCY of alleles IN POPULATION

  • 1) genetic drift 2) non-random mating 3) mutation 4) gene flow 5) natural selection

  1. genetic drift - random change due to chance

    • sample size (small vs large population)

    • bottleneck effect - change from a rapid decrease of population

    • founder effect - few leave to establish a NEW population

  2. non random mating - mates selected based on phenotype

  3. mutation - new alleles introduced

  4. gene flow (migration) - interbreeding populations

  5. natural selection - certain alleles more likely to reproduce

    • 1) stabilizing - favors intermediate phenotype, hates extreme variants

    • 2) directional - favors phenotypes at on extreme (environment)

    • 3) disruptive - favors extreme at range (not intermediate) phenotype

sexual selection

  • competition among men through combat/visual displays

  • females choose their men

9.2 —————————————

speciation

  • 2 species breed to make new species

reproductive isolation

  • populations become isolated (reproductively) if NO GENE FLOW

PRE - zygotic isolating - stop mating or prevent fertilization

  • 1) behavioral - special signals (songs)

  • 2) habitat - same area but different habitat

  • 3) temporal - timing differences

  • 4) mechanical - anatomical differences

  • 5) gametic - egg and sperm cant fuse

POST - zygotic isolating - sperm successfully fertilizes egg to form zygote

  • 1) hybrid inviability - genetic incompatibility (stops development of zygote)

  • 2) hybrid sterility - can mate and produce hybrid offspring (makes them infertile MULE)

  • 3) hybrid breakdown - first gen hybrids of crossed are fertile (but next gen not)

types of speciation

  • 1) sympatric - populations live in same habitat become isolated

    • plants - chromosome changes

    • animals - non random mating

    • polyploidy - errors in cell division (diploid instead of haploid in meisos)

  • 2) allopatric - populations separated by geography become isolated

    • gene flow gets separated and evolve to different pressures

adaptive radiation - population disperses into separate islands and adapt to environment

divergent evolution - species similar to ancestors become distinct

convergent evolution - species independently adapted

SPEED:

gradualism - evolution is slow pace before divergence. big changes occur overtime

punctuated equilibrium - evolution is long period no change. later periods of divergence

impact of human activities

  • wilderness into crops

  • tourism

  • buildings and roads