18.5 isolation & speciation
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how does speciation happen through adaptive radiation?
• species is seperated geographically • reproductive isolation / no gene flow / gene pools kept seperate • exposed to different selection pressures • variation due to mutations • change in allelic frequency / advantageous allele selected for • can’t interbreed to produce fertile offspring
what are the different isolation mechanisms?
geographical - seperated by physical barriers ecological - inhabit different habitats temporal - different breeding seasons behavioural - different courtship behaviour mechanical - genitalis don’t interact gametic - male gamete doesn’t fuse with female gamete hybrid sterility - hybrid doesn’t produce viable gamete / offspring
what is allopatric speciation?
species are seperated geographically -> prevent interbreeding
what is sympathic speciation?
speciation within a population within the same area & don’t interbreed
where does genetic drift occur?
occur in small populations w. smaller gene pool
what will result with a great effect of genetic drift?
population change rapidly & more likely to develop new species
how does genetic drift affect allelic frequency?
allele being passed on will cause great change due to high allelic frequency