01:119:115 Lecture Notes - Lecture 21: Species Problem, Allopatric Speciation, Species
13 Jul 2016
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Evolution theory must explain how populations evolve (last chapter) and how new species originate. Microevolution changes in allele frequency in a population over time. Macroevolution broad patterns of evolutionary change above the species level. Speciation = process by which one specie splits into 2 or more spp yield tremendous diversity of life (~1. 8 million have been identified) New spp that result share many characteristics because descended from common ancestor (figure 24. 2a & figure 24. 2b) The concept of biological species based on reproductive isolation. Group of populations whose members can interbreed in nature and produce viable, fertile offspring. Do not exchange genes with different species reproductively isolated. Reproductive isolation mechanisms to prevent two species from interbreeding and producing viable, fertile offspring. Hybrids = offspring of crosses between species. Different types of reproductive barriers fertilization (figure 24. 3) Tuesday, november 11, 2014 zygote from: prezygotic isolation mechanisms. Prezygotic barriers: occur before formed prevent fertilization taking place.
