Conservation implications of genetic variation in three rare species endemic to Florida rosemary scrub

Habitat conversion and fire suppression during the last 50 yr have greatly reduced and altered Florida scrub vegetation, resulting in threats to the p ersistence of its unique flora. As part of a larger conservation project, w e investigated patterns of isozyme variation in three rare perennial scrub plants with overlapping ranges endemic to Florida rosemary scrub on the Lak e Wales Ridge. All three species have low levels of genetic variation, comp arable to or lower than those generally reported for rare plants with restr icted geographic ranges. Liatris ohlingerae has more than twice the expecte d heterozygosity of the other two species, with little population different iation. In contrast, Hypericum cumulicola has highly differentiated populat ions with little apparent interpopulation gene flow and heterozygote defici encies indicative of inbreeding. Eryngium cuneifolium, the species with the narrowest range and fewest populations, has intermediate values for geneti c parameters. Although the three species have narrow and overlapping geogra phic ranges and similar habitat specificity, we discuss how optimal conserv ation of each species differs.