LIFE 121 Lecture Notes - Lecture 5: Meiosis, Adaptive Radiation, Cichlid
Document Summary
Members of same species are generally capable of interbreeding with one another to produce fertile offspring: reproductive barrier: biological feature of organism that prevents populations of closely related species from interbreeding when ranges overlap. Mechanisms of speciation: allopatric speciation: gene flow interrupted when a population is divided into geographically isolated subpopulations. Formation of land bridge: once geographic separation has occurred, one or both populations may undergo evolutionary change during period of separation, likelihood allopatric speciation increases when a population is both small and isolated. 2. sexual selection sympatric speciation: ex/ speciation of cichlid fishes in lake victoria in africa. Chromosomal changes sympatric speciation: polyploidy: results from accidents during meiosis that extra sets of chromosomes in some gametes. More common in plants than animals: adaptive radiation: evolution of new species from common ancestors introduced to new environments, isolated island chains with diverse habitats often sites of adaptive radiation (galapagos islands)
