A study of climate-induced evolutionary change in a California intertidal snail suggests that resource managers shouldnt focus exclusively on genetic diversity when developing conservation plans for protecting endangered or threatened species.

In the study, detailed in the June 1 issue of Science, biologists at the University of California, San Diego and at Louisiana State University measured the genetic diversity of populations of Acanthinucella spirata, a common marine gastropod, from Tomales Bay, 40 miles north of San Francisco, to San Diego. They discovered that the snails genetic diversity, the most commonly used gauge of a populations health, is highest in the Los Angeles area and lowest in the northern part of its range.

Measurements of genetic diversity now greatly influence decisions on where to locate protected reserves, since the most genetically diverse populations are assumed to be better able to withstand environmental changes. But while the snails around Los Angeles and to the south are genetically more diverse than those to the north, the researchers discovered that they are less diverse morphologically. This is due to the presence of a different shell form, or morphology, in some populations in the northern part of the range that is not found in the Los Angeles area or in regions to the south.

Theres a big difference in the morphologyin the shape and size of the shellsbetween the northern and the southern populations, says Kaustuv Roy, an assistant professor of biology at UCSD who conducted the study with Michael E. Hellberg, an assistant professor of biology at LSU, and Deborah P. Balch, a former student at UCSD.

Looking at the coast today, theres a dramatic decline in genetic diversity in this species going from south to north, he adds. But the northern regions have a greater amount of morphological diversity. So, which do you use to make conservation decisionsgenetic diversity or morphological diversity? Heres a ca
'"/>

Contact: Kim McDonald
kimmcdonald@ucsd.edu
858-534-7572
University of California - San Diego
31-May-2001