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MACROEVOLUTIO1 - matter of fact do animals evolve in...

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MACROEVOLUTION: TEMPO AND MODE. I We now consider the tempo (i.e., rate, and any modulation thereof) and the mode (i.e., the particular form or manner) of evolution. The use of these two words to focus the study of evolution is attributed to George Gaylord Simpson who's book, Tempo and Mode in Evolution, brought a paleontological perspective into the Modern Synthesis and applied the thinking of population variation and genetics the patterns of the fossil record. Thus, Simpson attempted to show that macroevolution (evolution above the species level) could be accounted for by familiar mechanisms of microevolution (genetic changes within population). He begins with the question: "How fast, as a
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Unformatted text preview: matter of fact, do animals evolve in nature?" To answer this question we consider evolutionary rates . Simpson identified two general classes of evolutionary rates: Phylogenetic (or morphological) rates measure the rates of evolution of characters (single or complexes) within phylogenetic lineages and are quantified as measured change in a character(s) per unit time ; taxonomic rates measure the rates at which taxa replace one another in the fossil record and are quantified by two reciprocal methods: 1) number of taxa originating and going extinct during a span of time, or reciprocally 2) the average number of years a taxon remains extant (more below)....
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