BIO-0014 Lecture Notes - Lecture 8: Allopatric Speciation
Document Summary
Anagenesis vs. cladogenesis: anagenesis is a change within a lineage, change over the course of time in one lineage, cladogenesis is when a lineage splits. Three types of speciation: allopatric geographic barrier, sympatric no geographic barriers, chromosomal no geographic. Migration-selection interaction: example with the snakes in two different environments, one banded one not banded. If migration stopped, then selection would be unopposed and the two populations would get more and more dissimilar. Plants are known to be plastic continually form new leaves, new flowers - organogenesis: if genetic differences. Allopatric model geographic barrier: primary contact: when populations slowly exchange genetic material by migration of individuals, migration reduces genetic differences between different population, attempts to homogenize the two species. Interrupt gene flow: between populations within a species by a barrier. Vicariance model: an actual barrier forms aka re-routing of a river.
