BIOL 206 Lecture Notes - Lecture 9: Limnetic Zone, Genetic Drift, Founder Effect
25 Aug 2016
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Document Summary
Speciation: evolution of reproductive isolation between populations: sexual reproduction: speciation requires the interruption in gene flow between populations, asexual reproduction: speciation is promoted by gene flow. Generally three stages to speciation: genetic isolation, physical isolation. Dispersal: prezygotic isolation, post-zygotic isolation, genetic divergence, genetic drift. Genetic drift increases with a smaller population: adaptation. Adaptations to difference habitats and resources, environment influences the species. How their exterior anatomy changes depending on the type of environment they are in b2. b3. Benthic are found at the bottom of the water column. Limnetic are found at the top of the water column: reproductive isolation, genetic incompatibilities, reinforcement. Selection against offspring of mixed mating leading to prezygotic isolation. Secondary contact: re-union of 2 population or species that diverged in isolation form a common ancestor. Hybridization: breeding between individuals from genetically different populations or species. Fitness of the hybrid offspring will differ from the parental population or species.
