BIOL 2200 Lecture Notes - Lecture 7: Ploidy, Speciation, Parallel Evolution

• School: University of Virginia
• Department: Biology
• Course: BIOL 2200
• Professor: Jessamyn Manson

Document Summary

Autopolyploidy: cell division error within a species leads to increase in chromosome number, diploid cell becomes tetraploid, tetraploids can interbreed with other tetraploids. Difference between reduced hybrid fertility and hybrid breakdown: reduced hybrid fertility low to no viable offspring after generation 1, hybrid breakdown- viable offspring after generation 1, but no viable offspring after generation 2. Back to sticklebacks : prezygotic reproductive isolation, habitat isolation some live at the bottom of the lake, some live at the top, sympatric speciation, parallel evolution example happens in different lakes. Over time 2 species arise from parent species: hybridization. Maybe geographically isolated and then come back together. Leads to interspecies mating and leads to creation of hybrids. Possible outcomes: reinforcement hybrids less fit than parents and selection will make them disappear. Two species stay two species: fusion barriers weak, gene flow occurs, two species become one species, stability little opportunity for selection to occur, low rate of hybridization.