MY

2.2 Speciation

taxonomy

domain → kingdom → phylum → class → order → family → genus → species

dumb kings play chess on fine green sand

  • binomial nomenclature → only first is capitalized

biological species concept

  • a group of individuals capable of interbreeding and producing viable, fertile offspring

  • issues:

    • fossilized → can’t know how they mate

    • Captivity vs wild → can interbreed (hybridize) in captivity

      • can hybridize in wild

    • molecular measure → how different is different enough?

    • asexual reproduction

speciation

  • macroevolution

  • 10 thousand to hundreds of millions of years

  • polyploidy → new species in 1 gen

  • gradualism → evolution proceeds by accumulation of gradual changes; constant rate

  • punctuated equilibrium → periods of rapid speciation and periods of no change; variable rate

allopatric speciation

  • a population is divided by a geographic barrier

  • no interbreeding between groups

  • gene pool changes through generations

  • could not reproduce if they reunited

  • allo = other // patric = land

sympatric speciation

  • one species becomes 2+ while living in the same geographic region

  • sym = same // patric = land

  • through reproductive isolation

adaptive radiation

  • many new species diversity rapidly from a common ancestor

  • often when environmental change leads to new resources and niches

reproductive isolation

pre-zygotic

  • habitat (ecological) isolation

    • same region, don’t encounter e/o

    • ground lizards vs tree lizards

  • temporal isolation

    • mate during different times of day or season

  • behavioral isolation

    • unique behaviors identify and attract same species

    • different mating dances

  • mechanical isolation

    • sex organs don’t fit together

  • gametic isolation

    • egg and sperm do not fuse into zygote

post-zygotic

  • reduced hybrid variability

    • hybrids fail to develop or are frail

  • reduced hybrid fertility

    • hybrids cannot reproduce

  • hybrid breakdown

    • hybrids okay in initial generation but future gens are weak/sterile