Local extinction event despite high levels of gene flow and genetic diversity in the federally-endangered Miami blue butterfly

Abstract

A certain level of genetic diversity and connectivity between populations is necessary to allow small populations to persist over time. In this study, we investigate the last two populations of the highly endangered Miami blue butterfly, one of which was extirpated in 2010. We investigate whether an erosion of genetic diversity was the cause for the extirpation of the Bahia Honda State Park (BHSP) population. As the level of existing molecular diversity within and gene flow between the last two populations of the endangered Miami blue butterfly was unknown, we present data from twelve polymorphic microsatellite loci as an assessment. We show that greater genetic diversity (allelic richness and observed heterozygosity) than originally predicted existed in the BHSP population prior to its extirpation and values were even greater in the Key West National Wildlife Refuge population. Allelic frequencies show short-range gene flow between neighboring habitat patches and underline the importance of habitat connectivity. It does not appear that loss of genetic diversity was the cause for the loss of the BHSP population. Greater consideration of habitat connectivity should be considered for short and long-term conservation and management of this taxon.