"The timing of the rate increases does not correspond to the appearance of key characteristics that have been invoked to explain the evolutionary success of these groups, such as hair on mammals or mammals' well-coordinated chewing ability or feathers on birds," Alfaro said.
"Our results suggest that something more recent is the cause of the biodiversity. It may be that something more subtle explains the evolutionary success of mammals, birds and fish. We need to look for new explanations."
Co-authors on the PNAS paper are Luke Harmon, a professor of biological sciences at the University of Idaho; Francesco Santini, a UCLA postdoctoral scholar in Alfaro's laboratory; Chad Brock, a graduate student of biology at Washington State University; Hugo Alamillo, a graduate student of biology at Washington State University; Alex Dornburg, a former undergraduate in Alfaro's laboratory, now a graduate student at Yale University; Daniel Rabosky, a graduate student of biology at Cornell University; and Giorgio Carnevale, a postdoctoral scholar at Italy's University of Pisa.
The research is federally funded by the National Science Foundation.
Alfaro's laboratory also studies why some groups of animals have great diversity in their shapes and others do not, even if there are many species. He and his colleagues use DNA sequencing to tease apart evolutionary relationships, analyze the fossil record and conduct sophisticated statistical analysis.
"We are interested in understanding the causes of biodiversity," Alfaro said. "We are trying to understand what explains the staggering diversity of reef fishes and other vertebrates."
"Our analysis can highlight how much higher extinction rates are in the present, compared with the historical rates," he said.
|Contact: Stuart Wolpert|
University of California - Los Angeles