SREL Reprint #3214

Dispersal via stream corridors structures populations of the endangered St. Francis' satyr butterfly (Neonympha mitchellii francisci)

Laura V. Milko1, Nick M. Haddad1, and Stacey L. Lance2

1Department of Biology, North Carolina State University, Raleigh, NC 27695, USA
2Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802, USA

Abstract: Habitat fragmentation may reduce gene flow and population viability of rare species. We tested whether riparian corridors enhanced gene flow and if human habitat modification between riparian corridors subsequently reduced dispersal and gene flow of a wetland butterfly, the US federally endangered St. Francis’ satyr butterfly (Neonympha mitchellii francisci). We surveyed nine populations throughout the taxon’s range using five polymorphic microsatellite loci. We found that genetic diversity of N. m. francisci was relatively high despite its restricted distribution, and that there is little evidence of population bottlenecks or extensive inbreeding within populations. We found substantial gene flow and detectable first generation migration, suggesting that N. m. francisci is unlikely to be currently endangered by genetic factors. Pairwise population differentiation and clustering indicate some structuring between populations on different drainages and suggest that dispersal probably occurs mainly via a stepping stone from the closest riparian corridors. However, genetic differentiation between geographically close populations suggests that isolation by distance is not solely responsible for population structure, and that management actions should be targeted at maintaining connectivity of riparian and upland habitats.

Keywords: Neonympha mitchellii francisci, Satyrinae, Butterfly, Microsatellite, STR, Corridors.

SREL Reprint #3214

Milko, L. V., N. M. Haddad, and S. L. Lance. 2012. Dispersal via stream corridors structures populations of the endangered St. Francis' satyr butterfly (Neonympha mitchellii francisci). Journal of Insect Conservation 2012(16): 263-273.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).