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Unformatted text preview: BIO 152 Notes Chapter 24: The Origin of Species habitat isolation temporal isolation behavioral isolation mechanical isolation gametic isolation reduced hybrid viability most offspring don't make, those that do are weak and frail reduced hybrid fertility offspring might be strong but it is sterile (donkey) hybrid breakdown one generation can make it but the next round is sterile or feeble morphological species concept characterizes a species by morphology (looks) *advantages sexual or asexual, useful without information on gene flow *disadvantages subjective, analogous structures paleontological species concept morphology based on fossils ecological species concept views species in terms of environmental niche autopolyploid individual with more than two chromosome sets (from single species) allopolyploids individual springing from two different species with more than two chromosome sets adaptive radiation the evolution of many diversely adapted species from a common ancestor upon introduction to new environments punctuated equilibrium shown from fossil records; species changes rapidly from its ancestor and then changes little for the rest of its existence exaptation structure evolved for one function becomes co-opted for another heterochrony evolutionary change in the rate or timing of developmental effects allometric growth the proportioning of relative growth rates during development that help give a body its specific form paedomorphosis reproductive development accelerates compared to somatic development and the adult form retains juvenile structures from an ancestor homeotic genes determine such basic features as where a pair of legs will develop or how a flower's parts are arranged Hox gene type of homeotic gene that determines fetal placement of features species selection species that endure the longest determine the direction of major evolutionary trends ...
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This note was uploaded on 04/11/2008 for the course BIO 152 taught by Professor Mort during the Spring '08 term at Kansas.
- Spring '08