sympatric speciation
speciation takes place in populations that live in the same geographic area
occurs when gene flow is reduced between groups that remain in contact through factors such as:
habitat differentiation
polyploidy/polyploid selection
presence of extra sets of chromosomes due to accidents during cell division
more common in plants than in animals
autopolyploid
offspring of mating between autopolyploids and diploids have reduced fertility
an individual with more than two chromosome sets, derived from one species
allopolyploid
species with multiple sets of chromosomes derived from different species
Allopolyploids can successfully mate with each other but cannot interbreed with either parent species
polyploidy, habitat differentiation, and sexual selection
Sexual selection
sympatric speciation can also result from the
appearance of new ecological niches
ex: North American maggot fly can live on native hawthorn trees as well as recently introduced apple trees
flies that use different host species are reproductively isolated by habitat and temporal barriers
can drive sympatric speciation
ex: sexual selection for mates of different colors has likely contributed to speciation in cichlid fish in Lake Victoria