17 speciation and hybridization

allopatric speciation

physical barriers stop gene flow

sympatry

situation where two or more species or populations co-exist in the same geographic area and potentially overlap in their habitats

sympatric speciation

the evolution of new species from a single ancestral species while they occupy the same geographic region, without geographic isolation

vicariance

new barrier splits population

dispersal (founder) event

small number of individuals colonize an isolated location

adaptive radiation

rapid speciation after colonization

niche

an ecological ‘role’ or ‘place’

autopolyploidy

a type of polyploidy where an organism has more than two sets of chromosomes, but all of these sets originate from the same species

allopolyploidy

a type of polyploidy where an organism has multiple sets of chromosomes, but these sets are derived from different species

reinforcement

if hybrids are less fit than their parents, anything that prevents hybridization will be strongly selected for

fusion

if hybrids are as fit as their parents, their 2 species may fuse back into one

hybrid stability

constant production of hybrids, usually as a result of hybridization between ecologically divergent species

hybrid speciation

hybrids are subsequently reprouctively isolated which promotes speciation