Evaluating spatial genetic structure of an endangered dioecious shrub (Lindera melissifolia) in South and North Carolina

Background/Question/Methods Lindera melissifolia (Walt) Blume is an endangered perennial dioecious clonal shrub that occurs in seasonally flooded wetlands located in one to four counties in eight states (AL, AR, FL, GA, MO, MS, NC, SC).  Previous isozyme research indicated extensive clonal growth in most populations, however these protein markers have been shown to not have as high of resolution power as DNA based markers. In this research, we used microsatellite genetic markers to determine the within site fine scale genetic structuring and genetic relationships among the sites in North and South Carolina. In addition, we tried to assess the sex ratios in each site. Skewed sex ratios and spatial segregation of the sexes could negatively effect the long-term viability of there isolated remnant populations.

Results/Conclusions All populations showed extensive genotype clones, with two to six genotypes per SC populations and 16 to 17 genotypes in the two NC populations. The NC populations were larger, had male and female flowering plants, and multiple genotypes of both sexes within each population. Some SC populations were as large as those in NC, however no female flowering plants were observed during the 2006 field season, there were few genetic individuals, and these few genotypes formed large single-genotype stands. We observed three female plants in Beaufort County (2007) and three female plants in one site of the Francis Marion National Forest (2009), indicating that some of the non-flowering individuals in our South Carolina populations may be female plants, but assessing gender is complicated by less frequent flowering in female Lindera plants. Limited genetic variation and the potential for single sex clonal populations or at the least highly skewed sex ratios (3500+ males: 1 female) could negatively effect the long-term viability of these South Carolina populations. Understanding the fine scale spatial genetic relationships and sex ratios is essential for effectively managing this endangered shrub.