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Desert Diary


Evolution often is thought of as acting very slowly, over thousands of years. Yet, we now know that some evolution through natural selection can occur very rapidly within species. A recent study makes it clear that man can affect natural populations of animals, causing noticeable changes within a few years. Bighorn Sheep in a Canadian population have been heavily hunted by hunters aiming to take rams with the largest horns. Between 1971 and 2002, horn size fell by about a quarter and has remained smaller even though no rams have been harvested in the latter few years of the time span. By targeting rams with the largest horns, hunters have cut short the length of time these rams normally would be breeding, leaving smaller-horned rams as the successful breeders.

What does this have to do with us? The environment determines who survives to breed and who does not. Some 13 thousand or more years ago, human hunters became part of the Chihuahuan Desert environment. Can we doubt that the game animals of our region have been affected?
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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.