Speciation Pt 2 There are different kinds of isolation that can lead to speciation; some are prezygotic and some are postzygotic. mechanical isolation: this occurs when mating pairs genitalia are not compatible with one another ex: plants reduced hybrid fertility: hybrid offspring can survive, but are unable to produce more offspring ex: ligers and tions, mules habitat isolation: mating pairs become geographically isolated from one another through migration or from physical barriers, do not reproduce, and over time end up being incapable of reproducing with one another ex: Galápagos finches, fish populations

Speciation Pt 2 temporal isolation: mating seasons occur at different times during the day, month, or year and this means that reproduction does not occur ex: toads and plants reduced hybrid viability: hybrid offspring do not live very long and subsequently do not reproduce ex: plants gametic isolation: reproductive cells between a mating pair are incompatible with each other ex: chimpanzee and humans

Speciation Pt 2 behavioral isolation: mating rituals/behaviors differ between mating pairs and mating pairs do not reproduce together as they do not recognize mating signs ex: birds hybrid breakdown: happening more often with plants, hybrids are viable, but as generations continue to reproduce, the hybrids become sterile

Prezygotic or Postzygotic? Consider the different types of isolation below. Indicate whether they are prezygotic or postzygotic and why. 1. mechanical isolation 2. reduced hybrid fertility 3. habitat isolation 4. temporal isolation 5. reduced hybrid viability 6. gametic isolation 7. behavioral isolation 8. hybrid breakdown 1. pre- 2. post- 3. pre- 4. pre- 5. post- 6. pre- 7. pre- 8. post-