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Archive for April 20th, 2007

The best snake is a live snake

Posted by Miqe on April 20, 2007

The return of spring means more outdoor activities for many Georgians, which can potentially lead to encounters with slithering reptiles. The Georgia Department of Natural Resources, Wildlife Resources Division (WRD) would like to remind Georgians that native venomous and nonvenomous snakes serve a vital purpose. Despite being misunderstood and often maligned, snakes represent an important part of Georgia’s ecosystems.

Georgia is home to 42 species of snakes, of which only six are venomous. But humans’ deeply rooted snake phobia can often lead to an untimely end for the reptiles.

“Even venomous snakes are harmless if left alone to go about their business,” said WRD Wildlife Biologist John Jensen. “It is disheartening that most of the snakes killed by people are essentially harmless and pose no real threat to humans.”

The 36 species of nonvenomous snakes found in Georgia are protected by state law and should not be killed. The preferred diet for snakes varies by species, but can include insects, frogs, rodents and even other snakes. Predation from snakes helps keep the population of many other species in check.

Non-venomous brown snakes are the species most commonly encountered in many parts of Georgia. Their tolerance for urban development and adaptability to a variety of habitats makes them a common species throughout the state, including metro Atlanta. The brown snake poses no danger to people or pets, and actually provides a benefit to gardeners because of its diet that consists primarily of invertebrates like slugs.

“A snake’s first response when confronted by a human is to flee the area or remain motionless in order to avoid detection,” Jensen said. “Snakebites occur when a snake is frightened and forced to defend itself. If simply left alone, a snake will usually try to leave the area.”

Of the 7,000 snakebites reported each year in the U.S. – a figure that includes non-venomous snakebites – 70 percent are determined to be avoidable. In most cases, the snake was seen well before the bite occurred, and simply walking away would have prevented the bite. Many of these bites are not even from wild snakes, but rather captive snakes biting their handlers.

In order to decrease the risk of snakebites, Georgians should use caution around fallen logs, vegetation, rocks and piles of debris, which provide shelter for snakes and the foods they eat. Use caution when moving such materials and avoid placing hands and feet into areas where a snake could be hiding. Should you encounter a venomous snake in the wild, simply move away from the snake and walk around the area.

For more information on snakes, call (478) 994-1438 or visit http://www.georgiawildlife. com , then click on Nongame Animals & Plants and go to the Backyard Wildlife link.

Residents seeking help in identifying a snake can email a photo of the snake through the “Contact us” link at http://www.georgiawildlife. com. Residents wishing to have a snake removed from their property should hire a licensed nuisance wildlife specialist. A list of licensed operators can be obtained from the WRD Special Permit Unit at (770) 761-3044.

From The Blade Plus

Posted in Herps in the news, International articles and news. | Leave a Comment »

Temperature Sex Reversal Implies Sex Gene Dosage in a Reptile

Posted by Miqe on April 20, 2007

Alexander E. Quinn,1* Arthur Georges,1 Stephen D. Sarre,1 Fiorenzo Guarino,1 Tariq Ezaz,2 Jennifer A. Marshall Graves2 Sex in reptiles is determined by genes on sex chromosomes or by incubation temperature. Previously these two modes were thought to be distinct, yet we show that high incubation temperatures reverse genotypic males (ZZ) to phenotypic females in a lizard with ZZ and ZW sex chromosomes. Thus, the W chromosome is not necessary for female differentiation. Sex determination is probably via a dosage-sensitive male-determining gene on the Z chromosome that is inactivated by extreme temperatures. Our data invite a novel hypothesis for the evolution of temperature-dependent sex determination (TSD) and suggest that sex chromosomes may exist in many TSD reptiles.

1 Institute for Applied Ecology, University of Canberra, ACT 2601, Australia.
2 Comparative Genomics Group, Research School of Biological Sciences, Australian National University, Canberra, ACT 0200, Australia.

* To whom correspondence should be addressed. E-mail: quinn@aerg.canberra.edu.au

From Science

Posted in International articles and news., Lizards, Science/Scientific papers | Leave a Comment »

 
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