Levels and patterns of genetic variation in three endangered vernal pool plants: Limnanthes vinculans (Limnathaceae), Lasthenia burkei, and Blennosperma bakeri (Asteraceae)

Within the last century, California vernal pool ecosystems have dwindled and been degraded by changes in land use threatening a number of specialized endemic plants. Conservation genetics involves the detection and preservation of evolutionary significant units (ESUs) within species, providing knowledge of the levels of genetic variation and its distribution among populations, which is of paramount importance for evaluating critical fitness attributes of rare species, and in developing recovery plans that can meaningfully sample and preserve genetic diversity. Within the context of mitigation, populations of endangered plants are increasingly being relocated to created seasonal wetland sites. Haphazard mixing of potentially genetically distinct populations in created sites could disrupt ESUs and prove harmful for long-term viability due to outbreeding depression. We investigated the genetic variation of three endangered plants occurring in Santa Rosa Plain (Sonoma County) vernal pools (Limnanthes vinculans, Lasthenia burkei,  and Blennosperma bakeri) using nuclear DNA markers. Early results indicate high genetic distinction (Phi_ST = 0.22) of remnant La. burkei populations in natural pools, and also suggest that plants in created pools came from a variety of distinct source populations that were mixed at created sites. Preliminary Li. vinculans data indicate high genetic diversity and low levels of genetic structure (F_ST = 0.06). Whether the low genetic structure among the Santa Rosa plain populations reflects contemporary gene flow or rather than historic gene flow via a large viable seed bank is yet unclear. B. bakeri results are yet forthcoming.