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Archives of The Cold Blooded NewsThe Newsletter of the Colorado Herpetological SocietyVolume 30, Number 6; June, 2003 |
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Threatened Asian Turtles The Texas Rat Snake Desert Tortoise Growing Fast or Living Longer African Clawed Frog Natural Freeze-Tolerance Eastern Indigo Snake PREVIOUS ISSUES 2002 Index Earlier Issues About the Cold Blooded News CHS Home Page |
Growing Fast or Living Longer, Take Your Pickby Marty MarcusReprinted from the newsletter of the Pacific Northwest Herpetological Society, Vol.18, No.4, April 2003.It's a real "feel good" experience to find out that an idea you've come up with over many years of working with reptiles has been demonstrated experimentally by a number of researchers and has now even been shown to apply at least to some reptiles in the wild. In the March, 2003, issue of Natural History magazine, Stephan Reebs, a biology professor in New Brunswick, Canada, has summarized some research recently done on Mount Wellington, Tasmania. The animals studied are known as Southern Snow Skinks (Niveoscincus microlepidotus), live-bearers, not egg-layers. The researchers. Mats Olsson of Sweden and Richard Shine of Australia, placed newborn skinks in pens on the same mountain in the same type of habitat where their mothers had been captured. The babies were individually marked and were offered plenty of extra food (worms). During the first 3 months they were weighed 4 times to determine their growth rates. Then they were released from their pens into the wilderness. Twice over the following 4 years they were recaptured. Those that were not recaptured were presumed to have failed to survive. And those who had grown the fastest prior to their release were noticeably absent from the group of survivors. While the physiological basis for the shorter life expectancy of fast-growers is still not clear, the evolutionary implications are different from what one might expect. Certainly, during any one breeding season, the fast-growers usually out-compete their rivals. But if they have a shorter life span, they may produce fewer total offspring because the longer-lived slower-growers have more opportunities to breed. The original research upon which Professor Reebs' summary is based appeared in the journal Evolution 56:1867-70, September 2002, under the title "Growth to Death in Lizards". | ||