BIOL 2400 Study Guide - Final Guide: Species Problem, Reproductive Isolation, Zygote
17 May 2014
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Document Summary
Summary: no definition of species works universally, usefulness highlights properties that we think are important for species. Focus on reproductive isolation does not make sense due to clonal reproduction. Issues with this approach: as we probe deeper into genetic composition of species that they"re more complicated then they appear to be. Occurrence of horizontal gene transfer and degree of gene sharing is changing our understanding of microbial species. Causes of reproductive isolation (figure on next page) Prezygotic processes that occur before a zygote forms (eg. green lacewings, hummingbirds, Postzygotic processes that occur after a zygote forms (eg. adenostoma and ceanothus: intrinsic, extrinsic. Divergent natural selection on an ecological trait. Mate preference associated with ecological trait leading to reproductive isolation. Ecological speciation the evolution of partial or complete reproductive isolation caused by divergent selection based on ecology. High rate of nonsynonmous substitutions within inversions, consistent with hypothesis that inversions important at maintaining species differences.
