How Old Is the Devils Hole Pupfish and Why Should We Care?

Authors: Christopher Martin

Year: 2018

Abstract

The Devils Hole Pupfish (DHP) is a conservation icon; however, one outstanding question about this species remains unresolved: how long has it persisted in its hellish environment? Here I discuss recent estimates of the age of this species, gene flow out of Devils Hole since colonization, and future directions. We previously used RADseq data to infer the history of pupfishes in Death Valley. Instead of relicts isolated for millions of years, we found evidence for frequent gene flow among Death Valley and Amargosa National Wildlife Refuge pupfish populations and divergence coinciding with the last glacial maximum 15 kya. We estimated that Devils Hole was colonized by pupfish approximately 1 kya, followed by genetic assimilation of pelvic fin loss, and recent gene flow into neighboring spring systems. We also estimated that some pupfishes in Death Valley exhibit the lowest genetic diversity of any wild population and may display the highest mutation rates of any vertebrate, as suggested by the extreme environmental conditions and life history characteristics of DHP. These results provide a new perspective on an iconic endangered species using population genomic methods and support the idea that repeated cycles of gene flow and renewal are needed to sustain a network of small pupfish populations in the desert.