When seeking to preserve biodiversity, simply trying to count and protect every species may not be enough. A new study suggests that conservationists should also consider the extent to which the mix of species in an area has the genetic potential to adapt to change.
In the past, many scientists assumed that the number of species in a region reflects that area's potential for evolutionary change. That potential is expressed in terms of "phylogenetic diversity"--a measure of how distantly related those species are. The higher the species number, the prevailing theory went, the higher the phylogenetic diversity, and the easier it would be for the area as a whole to adapt to global change.
When Félix Forest, Richard Grenyer, and colleagues at the Jodrell Laboratory of the Royal Botanic Gardens in Kew, U.K., and other research centers examined plant life in two biodiversity hot spots in South Africa's Cape region, however, they found that species number and phylogenetic diversity don't always go hand in hand. Analyzing sequence data from a gene present in 735 plant genera, the researchers found that while the western Cape had more plant species, the eastern Cape's flora had higher phylogenetic diversity. That diversity, in turn, had produced more plants with traits useful for food or medicine. The team presents its findings 15 February in Nature.
Botanist Terry Hedderson of the University of Cape Town says the results may help conservationists better decide which areas to protect: "A planner might ask, 'Where do I place my next reserve to capture the most evolutionary potential?' It is precisely in these circumstances that one would expect phylogenetic diversity to really come into its own."
Jonathan Eisen, an evolutionary genomics researcher at University of California, Davis, agrees that phylogenetics should be used by conservationists, but he cautions that predicting evolutionary change is tricky, as some lineages take millions of years to evolve significantly, while others evolve in much faster.