All these observations again beg the question

All these observations again beg the question - diversity...

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All these observations again beg the question: is diversity regulated , or put another way, can we treat the patterns of diversity in the fossil record as we might treat an ecological system ? There are inferences that support both answers to this question. Computer models where the rates of extinction and origination (speciation) fluctuated randomly . One constraint was that the mean probability of a taxon going extinct equaled the mean probability of it speciating . Thus, diversity would fluctuate but hover about some "equilibrium" value. Results produced patterns of diversity within clades very similar to those observed in the fossil record (see below). Data supporting the notion of regulation is the observation that rates of extinction and rates of origination are correlated. This suggests that when speciation increases diversity, extinction rates increase and bring
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Unformatted text preview: diversity back down; similarly if extinction rates increased, speciation rates would increase and bring diversity back up (beware of using a teleological argument; these changes are effects of changes in diversity presumably occurring due to ecological pressures at the time, not for the purpose of restoring diversity). Observation of correlation of extinction and speciation rates suggest diversity dependent effects or feedback in an ecological sense. Can also model patterns of increase in diversity as one would model exponential growth in ecology N t = N e rt where r = birth rate - death rate (or in our case, origination rate - extinction rate). N = 1 species (beginning of group) and t = time since first fossil...
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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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