An Examination of Gene Flow Among Distinct Management Units of The Reddish Egret
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The Reddish Egret (Egretta rufescens) is one of the least studied herons in North America. It ranges from Baja California to the Bahamas, north to Texas and Louisiana and southwards to Central America and the northern part of South America. I examined gene flow and genetic diversity among populations across the range of the species. I specifically tested hypothesized distinct management units (Western, Central, and Eastern) based on geographic distributions and the findings of Hill et al. (2012). We collected blood and feather samples from nestlings (n = 145) of eight sample sites (Baja California, Chiapas, Yucatan, Tamaulipas, Texas, Louisiana, Florida and the Bahamas). We extracted DNA from collected samples and used ten microsatellite markers and the mitochondrial control region to estimate deviations from Hardy-Weinberg equilibrium, genetic differentiation, population structure, and gene flow. In all analyses, I detected more differentiations among groups and regions (Fst = 0.21) than among populations within groups (Fst = 0.09). Our results revealed three primary breeding concentration centers, one in each of the management units (Baja California in the Western region, Chiapas for the Central region, and Bahamas for the Eastern region) providing further support for the previously established management units. We found greater differentiation among populations in our mtDNA analysis suggesting less movement across populations and management units and greater philopatry by females than by males. Recent banding and telemetry data also support differences in movement patterns between males and females. Lastly, gene flow between the Baja California population and the other populations is weak; whereas, we detected weak to moderate gene flow between sampling sites in Central and Eastern management units.