AUTHORS: Neil R. Balchan1, Owen M. Edwards1,2, Yucheol Shin3,4, Kaleb M. Banks1, Michael S. Reichert1, Bo Zhang1, Damien Esquerré51 Department of Integrative Biology, Oklahoma State University, Stillwater, OK 74078, USA
2 Oklahoma Biological Survey, University of Oklahoma, Norman, OK 73019, USA
3 Richard Gilder Graduate School, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA
4 Department of Herpetology, Division of Vertebrate Zoology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA
5 School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW 2522, Australia
ABSTRACT: The crawfish frog (R. areolata) is an ecologically enigmatic species that is endemic to the United States and is of conservation concern throughout most of its range. Despite recent research, little is known about population and landscape genetics of this species. Traditional taxonomic schemes have suggested the presence of a northern and southern subspecies, with an area of contact in Oklahoma. While these subspecies designations were based on morphological descriptions of disparate individuals and likely do not represent range-wide morphological or genetic, they have largely been accepted and used by various agencies. Here, we use genomic data to understand these themes in Oklahoma, with the goals of understanding the patterns of spatial genetics for this species. We use a panel of genome wide single nucleotide polymorphism loci to understand population differentiation, relatedness of individuals across the landscape, and connectivity of populations. We also explore the roles of two proposed biogeographic barriers, the Arkansas and Canadian rivers, in structuring subspecies limits. Finally, we use ecological niche modelling to explore how post-glacial expansion of species ranges might contribute to patterns of current population structure seen in the crawfish frog. Our data reveal that crawfish frogs in Oklahoma exhibit minimal genetic structuring, inconsistent with what would be expected for a contact zone between two evolutionarily significant units. Our models suggest a constrained distribution for this species in southern Texas during the last glacial maximum, and subsequent rapid expansion northward over the last 20,000 years as deglaciation occurred. Conservation approaches should consider the current genetic makeup of crawfish frogs when planning management efforts, and our data suggest little genetic differentiation among populations in northern parts of the current geographic distribution.
