Historically, biologists needed fossil records to study patterns of species diversification of lizards on the Caribbean islands. But advances in molecular methodology allowed Glor and Rabosky to use DNA sequences to reconstruct evolutionary trees that show the relationships between species.
The two scientists found that species diversification of lizards on the four islands reached a plateau millions of years ago and has essentially come to an end.
Glor said the extent and quality of the data used in the research allowed him and Rabosky to show that species diversification of lizards on the islands was not continuing and had indeed entered a state of equilibrium.
"When we look at other islands and continents that vary in species richness," said Glor, "we can't just consider rates of accumulation; we need to look at the plateau points."
Glor emphasizes that a state of equilibrium does not mean that the evolution of a species comes to an end. Lizards will continue to adapt to changes in their environment, but they are not expected to develop in a way that increases the number of species within a habitat.
Glor believes his work with Rabosky represents the "final word" on the importance of limits on species diversity over the rate of speciation when explaining the species-area relationship in anole lizards.
|Contact: Peter Iglinski|
University of Rochester