A Genetic Assessment and Hybrid Status of the Northern Leopard Frog (Lithobates pipiens) Along the Mora River in Northern New Mexico

Presentation: Rapid alterations to aquatic habitats in the Southwestern US are occurring due to climate change. The dramatic declines of the ubiquitous northern leopard frog, Lithobates pipiens, in the western US is a cause for concern. In this study, we investigate population-level connectivity of L. pipiens across a landscapes of agriculture, acequias, and protected lands and potential hybridization with L. blairi using nuclear (FIBI7 and microsatellites) and mitochondrial (ND1) markers. Interestingly, the nuclear FIB7 sequences demonstrate: 1) presence of an indel in morphologically designated L. pipiens one study believed to be unique in L. blairi, and 2) individuals heterozygous for the indel which may or may not be L. blairi x L. pipiens hybrids. The ND1 sequence analysis revealed close genetic distance of samples to L. pipiens in other western states. Microsatellite analysis indicates that two locally sampled populations, separated by a major interstate and differing in habitat type (mixed oak scrub vs plains) had limited gene flow (FST = 0.235) in comparison with populations along the riparian zone (FST = 0.0001). One sample, with incomplete insetting of the dorsolateral fold, grouped with L. blairi in the phylogenetic analysis of FIBI7 and provides some evidence of hybridization in the Mora Watershed. This study gives further support for what was previously anecdotal evidence of L. pipiens x L. blairi hybridization along the Mora River. Anthropogenic impacts as well as apparent isolation by distance provide some insight into factors influencing genetic structure of L. pipiens in drought susceptible aquatic habitats in the Southwest.