BIOL 180 Chapter Notes - Chapter 27: Adiantum, Inbreeding Depression, Zygote

• School: UW
• Department: Biology
• Course: BIOL 180
• Professor: Freeman Scott

Document Summary

Genetic isolation happens routinely when populations become geographically separated: speciation begins when gene flow between populations is reduced/eliminated, causing genetic isolation. Allopatry - (different-homeland) populations that are geographically separated: therefore speciation that begins with geographic isolation is allopatric speciation. Geographic isolation occurs in one of two ways: dispersal, vicariance. Vicariance - physical splitting of a habitat. Founder effect (2) natural selection in new environment could favor alleles associated with large beaks: new population of large ground finches is not yet considered a separate species from migrant population because some gene flow continues to occur. Given enough time though the populations may continue to diverge. Dispersal and colonization, followed by genetic drift and natural selection is thought to be responsible for speciation in galapagos finches and many other island groups. If a new physical barrier like a mountain range or river splits a geographic range of a species, vicariance has occurred.