THE MINNESOTA HERPETOLOGICAL SOCIETY Volume 20 Number 8
August 2000 Newsletter
Upcoming Meeting The Vice-president's Report By Totty Gamble September General Meeting Program: "Understanding Environmental Sex Determination in Reptiles" Guest Speaker: Dr. Fred Janzen September's speaker, University of Iowa professor Fred Janzen, will be discussing one of the more intimate details of reptilian life, sex. Specifically, what makes one animal male while another is female. Reptiles have two methods to detennine gender. The first method, genetic sex determination (GSD) , should be familiar to most of us since humans (and other mammals) use this process, and it is characterized by gender resolution at fertilization. The other alternative, that reptiles have developed, several times independently, is environmental sex determination (ESD). This is a process where outside factors (like temperature, humidity, pH, etc. ..) determine the offsprings sex, after fertilization. The most common fom) of ESD in reptiles is temperaturedependant sex determination (ISO). All species of crocodilians, many turtles, and a few lizards (notably, some gecko and lacerta species) posses TSD. Dr. Janzen's work to understand these processes has focused primarily on the sex determining methods of North American turtles. He will also discuss some of the other research he and his students are working on including conservation genetics and
molecular phylogeography of Great Plains reptiles.
Giant Bullfrogs Invade Canada
Are you keeping TSD herp species (turtles, geckos, crocodilians, etc ...)? Are you interested in reptilian development and reproductive biology? Do you have an interest in Midwestern herp species? This meeting wiB have something of interest to you.
July 26, 2000 10:51 am EST VICTORIA, British Columbia (Reuters) - Baseball-size bullfrogs are invading large areas of British Coltunbia and endangering native species with their hearty appetites, according to a Canadian biologist
Upcoming meetings: Oct 6, 2000 - Dr. Robert Powell "Adventures in the Caribbean: Herpetology on Tropical Islands." Nov 3, 2000 - LJan Keyler and Jim Gerholdt "Herpin' New Mexico, part deux" January Breeders
5,
2001
Minnesota
March 2, 2001 - Phil Tremper "Breeding Rare Geckos"
Notice Due to the Labor Day Holiday The next meeting is September 8, 2000
Bylaw Changes A copy of the changed Bylaws will be in your next newsletter. Start thinking no\-\' if you would like to run for a Board position. Remember the elections \-vill be held in December 路with the new Board taking effect in January.
The intruding Rana Catesbeiana, more commonly known as the American Bullfrog, is the largest frog in North America with females weighing up to 24.5 ounces. University of Victoria biologist Pumima Govindarajulu, probing the sudden increase in the number of bullfrogs, said the voracious predators are threatening delicate aquatic ecosystems in Victoria, Duncan. Nanaimo and Parksville.
"The main problem is that bullfrogs eat other frogs and snakes as well as insects, fish, mice, and young birds. Actually they'll eat whatever they can fit into their huge mouths," Govindarajulu told Reuters. Bullfrogs are naturally only found in eastern parts of North America. It is believed they 'were brought to the west coast by people who wanted to sell them as a delicacy or as live ornaments for garden pools. 11)ey were first nored in the 1940s but their numbers did not explode until the eady 1990s. To find out more about presence and number of bullfrogs in British Columbia the biologist is looking for volunteers who lend a listening ear and spot out the invaders. "It's easy to identify them in summer because they have a loud breeding call." Submitted by Heather 1I1gbrctsofl