CHED 1500 |
| Evolution of populations within species is driven by natural selection, genetic drift and mutation pressure. Favoring rapid evolution are big population sizes, short generation times, and strong natural selection. Human change of the biosphere results in strong selection pressure because ecosystem properties have been so seriously altered. For species with big population sizes and short generation times, rapid evolution is often the result such as in many microbial disease organisms, small insects, common fisheries species and annual plants. Species with small populations or long generation times tend not to respond to human change evolutionarily but instead exhibit rapid declines in population numbers: such species are most likely to be listed as endangered or extinct. Human action can also affect speciation rates. The most rapid speciation occurs when disruptive selection occurs across a landscape where movement is curtailed. When humans create a fragmented landscape across an environmental mosaic, rapid divergence and reproductive isolation can result. Rapid evolution due to human environmental change is not just an intellectual curiosity. It generates huge costs in medical care and in agricultural losses. It may also increase the rate of evolution of highly virulent diseases or particularly noxious weeds. |
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Chemical Evolution from Origins of Life to Modern Society
1:30 PM-4:55 PM, Tuesday, April 8, 2008 Hilton New Orleans Riverside -- Jasperwood, Oral
Division of Chemical Education |