The founder effect is a special case of disruptive selection. Cockroaches becoming increasingly resistant to pesticides is an example of disruptive selection. Biston betularia provides us with a famous example of stabilizing selection. Allopatric speciation involves changes in mating behavior, while sympatric speciation involves changes in feeding behavior. Sympatric speciation is known to be common, while allopatric speciation is still just proposed model of speciation.
Sympatric speciation occurs only in plants, while allopatric speciation occurs in animals.
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