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Desert Diary


Talk of a bottleneck might well bring to mind a container of wine (or in older times, before the ubiquity of aluminum cans, of beer or pop). That's not quite what population geneticists have in mind, though. When a large population undergoes a population crash and then recovers its size, the population low is the bottleneck, the constriction. The post-crash population is quite different genetically than the original. Organisms normally have enormous amounts of genetic variability; so much variation, that the relatively few individuals making it through a bottleneck don't have the capacity to carry it all. The result? The post-bottleneck population lacks much of the variability of its ancestors.

The importance of variability is in the chances that a variable population will have some individuals suitable for almost any reasonable environment—individuals that have a fighting chance of surviving environmental changes, whether of climate, competition, disease, or whatever. Lacking such high genetic variability, threatened animals like our Whooping Crane and California Condor, even if they survive their current bottlenecks, may be at risk for thousands of years.
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Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.


Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.



Web Resources

Evolution 101