ShabelEvol7 - Bio 1B, Summer 2009 Professor Alan Shabel...

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Bio 1B, Summer 2009 Evolution, Lecture 7 Professor Alan Shabel Page 1 of 2 Updated on 1 July 2009 (501–504, 525–531) Macroevolution refers to evolutionary change on the grand scale, including the formation of species, the diversification of species, and the appearance of major evolutionary novelties. Macroevolution also encompasses problems related to mass extinction events, the subject of a later lecture. Is macroevolution simply microevolution “writ large,” or is macroevolution characterized by a distinct set of evolutionary forces and mechanisms? The tempo and mode of evolution . Gould and Eldredge contrasted their model of punctuated equilibrium with Darwin’s model of phyletic gradualism . A key observation behind the idea of punctuated equilibrium is that fossil lineages tend to appear abruptly in the fossil record, and then they persist relatively unchanged over long periods of time. Thus, long periods of stasis are punctuated by brief episodes of speciation. A key question is whether this pattern is the result of the imperfections of the fossil record, or
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This note was uploaded on 07/04/2009 for the course BIO 1B taught by Professor Carlson,mischel,power during the Summer '07 term at University of California, Berkeley.

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ShabelEvol7 - Bio 1B, Summer 2009 Professor Alan Shabel...

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