"The generalities are astounding when you start looking across different continents, different species, different habitats," said Dr. Thom DeWitt, Texas Agricultural Experiment Station fisheries researcher and Texas A&M University Sustainable Coastal Margins Program member. "We are learning about how man's impact on the environment is causing changes in body shape in fishes, and ultimately that could be important in conservation and management planning."

DeWitt's lab is examining various species of fish from Texas, South America and Africa to determine how factors such as predators or water flow result in body shape differences among the same species. He said knowing how body shape relates to the environment helps biologists create ways to manage fish for sustainable use.

"Predators cause fishes to grow longer tails that allow them to swim faster when they are startled, and that makes perfect adaptive sense," DeWitt said. "And the patterns we are studying in our own backyard here in Texas apply worldwide."

In Texas, the Gambusia affinis, or mosquitofish, is one such fish found in the study to have adapted to being raised with predators by growing a longer tail. That's important, he said, because the state has several endangered species of Gambusia.

"Anything we learn about the 'weed' species can inform us about conservation planning for the endangered species," DeWitt said.

His research group has found similar patterns for a Gambusia species from the Bahamas as well as similar patterns for guppies from Trinidad.

Other aspects of habitat also impose different body shapes, he added. Fish apparently adapt to flowing or non-flowing environments, being in lagoons versus channels, for necessities such as fee
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Contact: Kathleen Phillips
ka-phillips@tamu.edu
979-845-2872
Texas A&M University
17-Jul-2002