California Desert Studies Consortium

Identifying Causes of Genetic Diversity Desert Reptile Populations

 

In the extreme heat of summer, you may find Dr. Eric Routman, professor of biology at San Francisco State, and his bold students looking for lizards on the rocky slopes near the CSU Desert Studies Center at Zzyzx, California. Dr. Routman’s group is studying desert lizards to help address a long-standing evolutionary puzzle—what factors most strongly contribute to the genetic diversity of a species? Although mathematical models have been quite successful at linking genetic variation to a number of potential evolutionary drivers (drift, selection, gene flow, mutation, recombination), conclusive evidence of these links using natural populations has been far more difficult to attain. Applying traditional DNA sequencing as well as next-generation shotgun sequencing to estimate levels of genetic diversity, Routman and his students have shown that some desert reptile species possess extraordinary levels of genetic variation while others have much less, despite being found in the same desert location. The various species also differ in population sizes, potential for gene flow, generation time and other factors that are predicted to affect genetic diversity. By comparing these factors for species that are closely related and found in the same location, these desert reptile studies provide better control for variation in mutation rates and population histories than typical comparisons made across a broader taxonomic range.​​