Microsatellite polymorphism in the endangered snail kite reveals a panmictic, low diversity population
Genetic structure and genetic diversity are key population characteristics that can inform conservation decisions, such as delineating management units or assessing potential risks for inbreeding depression. Evidence of genetic structuring or low genetic diversity in the critically endangered snail kite (Rostrhamus sociabilis plumbeus) would have implications for monitoring and planning decisions. Recent work on understanding connectivity across the snail kite range indicated that there is less dispersal between northern and southern parts of the current range, and that dispersal is shaped by individual habitat preference. We examine whether there is neutral genetic structure and the amount of genetic variation in the population by non-lethally sampling 235 nestlings from unique nests across the entire breeding range between 2013 and 2014. Data on 15 microsatellite revealed low diversity (e.g., N a = 2.54, H e = 0.37) and range-wide panmixia based on AMOVA, Bayesian clustering, spatial autocorrelation, isolation by distance, and spatially explicit ordination analyses. Our results emphasize that long-term recovery goals and management strategies should be based on viewing snail kites as a single genetic population, despite evidence for non-random dispersal between wetlands over ecological time scales. These results also highlight the need to understand potential effects of low genetic diversity on population dynamics and viability of snail kites. More broadly, these results add to the growing evidence for potential discrepancies between dispersal and genetic patterns, emphasizing that care should be taken if using one to interpret the other, particularly for widely-ranging species.
KeywordsPopulation structure Genetic diversity Dispersal Snail kite Everglades
We are grateful to Cortney Pylant for advice and training in the lab. We thank Lauren Diaz and Andy Revell for help with genetic labwork, John Hargrove for advice on genetic analyses, Brian Jeffery for help mapping site locations, and Caroline Poli for help with Inkscape. We acknowledge all current and previous graduate students, project managers, and technicians that have contributed to snail kite data collection and data management over the last 20 years. We thank Wiley Kitchens, previous principal investigator of the snail kite monitoring project, as well as Julien Martin, and Denis Valle for guidance and for reviewing earlier versions of this manuscript. We would also like to thank two anonymous reviewers and the associate editor for reviewing this manuscript and providing helpful feedback. The US Army Corps of Engineers, Florida Fish and Wildlife Conservation Commission, US Fish and Wildlife Service, St Johns River Water Management District, and the US Geological Survey provided funding for this study. This study was also supported by a Dean Amadon Grant (Raptorresearchfoundation.org). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
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