During the initial colonization of the Virgin Islands by Europeans in the seventeenth century, the islands were almost completely deforested to make way for plantations. The resilient island flora recovered somewhat following the collapse of the sugar market and the abolition of slavery in the nineteenth century. However, in modern times development, habitat loss, and exotic species continue to threaten the forests of the Virgin Islands. Many plants known to have been widespread during the nineteenth and early twentieth centuries are now extinct or extremely rare and confined to just one or two islands. Solanum conocarpum Dunal in Poir. (Solanaceae) was thought to be extinct until two individuals were discovered on the US Virgin Island of St. John during the 1990s. Since then, two more wild individuals have been discovered in dry forest habitat on St. John. The known wild population of S. conocarpum consists of only those four individuals, and the cultivated population consists only of the offspring and clones of those individuals. In order to assess the genetic diversity of this species, we used thirteen randomly selected 10-mer primers to perform RAPD (randomly amplified polymorphic DNA) fingerprinting analysis. We also performed RAPD analysis for a common S. conocarpum congener, Solanum polygamum Vahl, a plant found in dry forest habitat on the US and British Virgin Islands and Puerto Rico. We sampled five S. polygamum populations on the islands of St. John and St. Thomas in the US Virgin Islands. Allele frequencies (p), heterozygosity (H), polymorphism (P), and similarity matrices, calculated for each population and species, revealed a significant loss of genetic variation in S. conocarpum.

Key words: RAPD, rare, Solanum conocarpum, Virgin Islands