The publication of the idea of punctuated equilibria set off a bit of a challenge among paleontologi

The publication of the idea of punctuated equilibria set off a bit of a challenge among paleontologi

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The publication of the idea of punctuated equilibria set off a bit of a challenge among paleontologists to show that their "own" mode of evolution was the correct one. Thus gradualists came out with papers showing convincing evidence of gradual evolution (figure 20.7, pg. 565) and the Punc. Eq. types came out with papers showing rapid shifts in phenotype in the fossil record. The absurd example is a data set by Gingerich which he interprets as gradual and is reinterpreted by Gould and Eldredge as punctuational! (see below). Like any polarized debate, there are two kinds of intermediates where reality lies: 1) some data sets show one mode, others show the other and 2) documented cases of punctuated gradualism : periods of stasis punctuated by short periods of gradual change. What remains to be confirmed is whether
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Unformatted text preview: different lineages tend to show one pattern and others the other: the relative frequency of the two alternative modes in the fossil record will ultimately settle the debate. The punctuation debated focused a lot of interest on the notion of hierarchical phenomena (sensu units of selection). One important hierarchical issue is Species Selection : differential rates of increase or decrease in species diversity among different lineages due to differences in rates of speciation and/or extinction. The basic principles of species selection are 1) speciation is random with respect to phenotype, 2) most changes occur at speciation, 3) different extinction and speciation rates are due to some biological properties of the different taxa....
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This note was uploaded on 11/06/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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