Allozyme Investigation of the Trillium pusillum Michaux Complex (Trilliaceae): Taxonomic and Conservation Implications

Abstract

TIMMERMAN-ERSKINE, M. (Science Department, Lansing Community College, Lansing, MI 48901), J. BALLENGER, (Department of Biology, Columbus State University, Columbus, GA 31907), R. R. DUTE, AND R. S. BOYD (Department of Biological Sciences, Auburn University, AL 36849-5407). Allozyme Investigation of the Trillium pusillum Michaux Complex (Trilliaceae): Taxonomic and Conservation Implications. J. Torrey Bot. Soc. 130:110. 2003.-The Trillium pusillum complex, comprising at least six suggested taxa, has a confused taxonomic history. Allozyme electrophoresis of seven loci from 15 populations of T. pusillum revealed genetic differentiation among populations but not enough to clearly subdivide the complex into species or varieties. Cluster analysis, using the unweighted pair group method and Nei's genetic identity values, revealed that populations of T. pusillum var. texanum and var. ozarkanum clustered separately from T. pusillum var. alabamicum and var. virginianum. We found high levels of genetic variation both within and between populations. Values of FST tended to be high (FST = 0.309), an indication of limited gene flow, in contrast to fairly high interpopulational genetic identities. However, mean genetic identity (0.733) suggested low to moderate differentiation between populations. Collectively, these data and the wide distribution of T. pusillum populations suggest that this once contiguous taxon is showing effects of genetic drift. Despite the high level of genetic diversity observed, limited gene flow and habitat destruction could threaten the survival of some elements of this species complex.