Speciation

speciation

origin of species

microevolution

changes in allele frequencies with a single gene pool

macroevolution

evolutionary change above the species level; cumulative effects of speciation over long periods of time

species

population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offsprings

reproductive isolation

barriers that prevent members of 2 species from producing viable, fertile offspring

prezygotic barriers

prevent mating or hinder fertilization

examples of prezygotic barriers

habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation

postzygotic barriers

prevent hybrid zygote from developing into fertile adults

examples of postzygotic barriers

reduced hybrid viability, reduced hybrid fertility, hybrid breakdown

morphological

by body shape, size, and other structural features

ecological

niche/role in community

phylogentic

share a common ancestor

allopratic speciation

occurs when populations are geographically isolated, leading to the formation of new species.

sympatric speciation

occurs when populations evolve into new species within the same geographical area.

autopolyploid

extra sets of chromosomes

allopolyploid

two species produce a hybrid; species a (2n = 6) + species b (2n = 4) →hybrid (2n = 10)

gradualism

common ancestor; slow, constant change

punctuated equilibrium

long periods of stasis punctuated by sudden change seen in fossil record