A study of climate-induced evolutionary change in a California intertidal snail suggests that conservation plans for protecting endangered or threatened species should not focus exclusively on genetic diversity. The research is funded by the National Science Foundation (NSF).
In the study, detailed in the June 1 issue of Science, biologists at the University of California, San Diego, and Louisiana State University measured the genetic diversity of populations of Acanthinucella spirata, a common marine gastropod from San Francisco to San Diego. They discovered that the snail's genetic diversity, the most commonly used gauge of a population's health, is highest in the Los Angeles area and lowest in the northern part of its range.
"This novel study provides a new angle to research on genetic/morphologic diversity," says Rich Lane, director of NSF's geology and paleontology program, which funded the research. "It has been thought that morphologic variation is greatest in populations where genetic diversity is highest. While that may be logical, here is a case where it is not true. The bottom line is that greater care and investigation may be needed in choosing locations of biological reserves, and in considering environmental and ecological decisions."
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 southward 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.