Comparative Genetics of Seven Plants Endemic to Florida’s Lake Wales Ridge

Genetic variation is often low in narrowly endemic species, and may be further depleted by habitat loss and fragmentation. Few studies have tested predictions about the distribution of genetic variation among co-occurring endemic plants species. We describe genetic variation and its relationship to life history traits for seven narrowly endemic, federally endangered Florida scrub species: Dicerandra christmanii, D. frutescens, Eryngium cuneifolium, Hypericum cumulicola, Liatris ohlingerae, Nolina brittoniana, Warea carteri. These species have varying life histories, degrees of habitat specialization, and geographic distributions. Measures of genetic (allozyme) diversity (mean number of alleles/locus, percentage of loci polymorphic and expected heterozygosity) varied among species. However, genetic variation was generally lower than published means for plants and also generally lower for means for comparable groups (endemics, short-lived herbs, species with mixed mating systems, species with gravity dispersed seeds). The chief exception was L. ohlingerae, which had relatively high genetic variation. All three measures of genetic variation produced the same ranking among species: L. ohlingerae > D. christmanii > N. brittoniana > E. cuneifolium > D. frutescens > W. carteri > H. cumulicola. For six of these species, we compared genetic variation with rankings of eight life history factors. Genetic variation was highest in long-lived, demographically stable, outcrossing species with long pollinator dispersal distances. Attributes such as median population size, habitat specificity, geographic range, and estimated primary seed dispersal distances were not related to rankings for genetic variation. The studied species varied widely in genetic differentiation among populations (0.02 < Fst < 0.72). The most differentiated species, H. cumulicola, is pollinated by specialized bees that may move short distances, therefore limiting gene flow among isolated patches. These comparisons emphasize that co-occurring narrowly endemic species can have a diversity of genetic patterns and that many factors can influence the amount and distribution of genetic variation. Further loss of genetic variation due to habitat loss and fragmentation will impact the genetic variation of these species differently. A single conservation strategy for this suite of species is therefore unlikely to achieve genetic conservation goals.