BIOL 123 Lecture Notes - Lecture 17: Gamete, Meiosis, Disruptive Selection
Document Summary
Species may be isolated by a failure to reproduce that occurs after fertilization, which will select for isolation before fertilization. Sometimes they produce offspring, but the offspring are sterile, and won"t be able to exchange offspring. Breakdown of gene exchange after fertilization of hybrids. Some hybrids can mate among themselves, but at this point, you get a low production of offspring, which will peter out the movement between species and can"t succeed successfully. If there are 2 populations with genetic differences, with post-zygotic isolation, there would be selection for pre-zygotic isolation to not form offspring with the wrong species. Strong reinforcement by isolation so species don"t make low fitness or. Geographical separation of populations fosters speciation sterile offspring. Different geographical separation, where the species are separated, making individual species evolution over time. Barrier develops, isolating the species, and over time, the species will have separate evolutionary histories, due to environment.
