Genetic diversity affects the evolutionary potencial of any species. The geographic distribution of plants is a good predictor of such diversity. In general widespread species exhibit higher levels of genetic diversity than rare taxa. The purpose of this study was to describe the amount of allozyme variation for four species in the genus Lepanthes (Orchidaceae): one with widespread and three with restricted geographic distributions within the island of Puerto Rico. We also looked at the amount of genetic differentiation among populations. We sampled 12 populations of the widespread L. woodburyana, for a total sample size of 288 individuals; for the narrowly distributed L. eltoroensis, L. sanguinea, and L. caritensis we sampled 5 populations per species for a total of 48 inviduals per species. Allozyme variation indices for Lepanthes species in Puerto Rico are higher than the reported average for plant species. Both rare and widespread Lepanthes show similar levels of allozyme variation. Most of the variation (80-93%) was found within populations, while a small fraction (7-20%) was located among populations. Factors other than geographical distribution contribute to high levels of allozyme variation for Lepanthes.

Key words: Genetic diversity, genetic structure, geographical distribution, inbreeding, Orchidaceae