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lecture10 - BioEE 278 Evolutionary Biology Fall 2007...

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BioEE 278 Fall 2007 Evolutionary Biology Lecture 10 MACROEVOLUTION: PATTERNS OF DIVERSITY A. Changes in taxonomic diversity over evolutionary history. 1. Estimating changes in diversity. a. counts of number of taxa in the fossil record – taxa are distinguished by morphology. b. counts are made for each geological "stage". b. do we count species, genera. families, etc.? c. are counts an accurate reflection of actual diversity (stages vary in duration, volume of exposed sediments differ, "pull of the Recent"). 2. Modeling changes in diversity. a. origination and extinction rates (like births and deaths) b. changes in diversity depend on S and E c. logistic models assume some sort of density-dependence (origination rates decline or extinction rates increase as number of taxa increases) 3. Patterns of taxonomic diversity through the Phanerozoic. a. the marine fossil record b. evidence for increasing diversity and for episodic mass extinctions B. Extinction.
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