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My_Ch24_lecture(2009030423565651) - Chapter 24 Origin of...

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Chapter 24: Origin of Species Purpose —to understand patterns of isolation and evolution that lead to speciation (origination of new species). Major AP Themes are the same as Ch 22, 23. What you MUST know in Ch 24: Micro vs. Macro-evolution Reproductive isolation mechanisms Allopatric vs. sympatric speciation Polyploidy Adaptive radiation Convergent evolution & analogous structures (Ch 25, p. 477) Note: Cliff’s has an excellent review of evolution concepts, with some good, clear diagrams for Ch 22-24; much easier Macroevolution is the patterns of changes in groups of related species over broad periods of geologic time, leading to the origin of new taxonomic groups (new species, genera, families, kingdoms). Microevolution is the shorter-term generation to generation changes in a population’s allele or genotype frequencies (think Hardy-Weinberg equilibrium; the opposite of H-W are the 5 causes of microevolution: genetic drift, gene Back to MACRO-evolution: Speciation is the formation of new species Species is a population whose members are capable of interbreeding in nature, to produce viable (can survive), fertile (can reproduce) offspring. The largest group in
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which genetic exchange is possible, and that is genetically isolated from other populations (cannot interbreed with other species). Theories of Macroevolution : (Fig 24.13, p 457) 1. Phyletic Gradualism Evolution occurs by the gradual accumulation of small changes; speciation occurs over long periods of geologic time But paleontologists rarely find intermediate fossil forms; gradualism proponents argue that the fossil record is incomplete… but maybe it’s getting there… The April, 2006 report of a 375 million year old, apparently intermediate fish/amphibian fossil presents an interesting piece of evidence for gradualism proponents! Check out the link to the article on
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My_Ch24_lecture(2009030423565651) - Chapter 24 Origin of...

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