A sequential approach using genetic and morphological analyses to test species status: the case of United States federally endangered Agalinis acuta (Orobanchaceae).

PREMISE OF THE STUDY Given that inaccurate taxonomy can have negative consequences for species of conservation concern and result in erroneous conclusions regarding macroecological patterns, efficient methods for resolving taxonomic uncertainty are essential. The primary objective of this study was to assess the evolutionary distinctiveness of the federally endangered plant species Agalinis acuta (Orobanchaceae) to ensure it represents a distinct taxon warranting protection under the United States Endangered Species Act. METHODS We describe and implement a sequential approach that begins with the most restrictive criteria of genealogical exclusivity within which we first conducted a phylogenetic analysis based on six chloroplast DNA loci assayed from multiple representatives of five putative species. Because of the possibility that incomplete lineage sorting is responsible for the lack of genealogical exclusivity among A. acuta individuals, we then conducted intensive population level analyses based on 21 microsatellite loci and 61 morphological traits. KEY RESULTS The distinctiveness of A. acuta from Agalinis decemloba and Agalinis tenella was not supported under the genealogical species concept. The results from the analyses of microsatellite loci and morphological characters evaluated under alternative species concepts also did not support the distinctiveness of A. acuta from A. decemloba . CONCLUSIONS Through this successive approach, we found insufficient evidence to support the evolutionary distinctiveness of the listed taxon A. acuta . We recommend that it be synonymized under A. decemloba and also conclude that the taxon that would now include A. acuta is deserving of protection under the Endangered Species Act.