In an article published Thursday, Dec. 4, in the journal Nature, postdoctoral fellow Ryan Calsbeek and Professor Thomas B. Smith of the UCLA Center for Tropical Research report that lizards long thought to be evolving independently on Caribbean Islands in fact exchange genetic material. The reason, according to their 12-month study: Hurricanes and lesser storms wash the lizards into prevailing ocean currents, which carry them from island to island.
"The lizards are being prevented from evolving as quickly as they otherwise would have," said Calsbeek, the study's lead researcher. "We can no longer just assume that certain populations evolved independently on separate islands."
The study questions the widely held view that vast numbers of species of plants and animals on Caribbean, Hawaiian and Galapagos islands evolved separately in isolated microcosms of evolution. As a result, the research sheds new light on the mechanisms of evolution of animals in island habitats and their ability to adapt in the future.
Smith, an evolutionary biologist and director of the Center for Tropical Research at the UCLA Institute of the Environment, explained that the exchange of genes among adjacent islands over time can slow evolution and the ability of animals to adapt to their surroundings. "When islands evolve independently, they maintain their own identity," Smith said. "When they begin sharing genetic material, their uniqueness begins to disappear, and the process of evolution slows."
Calsbeek and Smith focused the study on Anolis lizards, a genus of lizards long considered a classic example of adaptive radiation -- the process whereby a single lineage rapidly evolves into many species that are adapted to specifi
Contact: Phil Hampton
University of California - Los Angeles