Extremely Low Levels of Allozyme Variation in Southern Korean Populations of the Two Rare and Endangered Lithophytic or Epiphytic <Emphasis Type="Italic">Bulbophyllum Drymoglossum</Emphasis> and <Emphasis Type="Italic">Sarcanthus Scolopendrifolius</Emphasis> (Orchidaceae): Implications for Conservation

Allozyme variation was investigated in two local populations of Bulbophyllum drymoglossum and three populations Sarcanthus scolopendrifolius, two rare and endangered lithophytes and epiphytes from South Korea. Genetic diversity was extremely low within populations (mean H _e = 0.011 for B. drymoglossum; 0.002 for S. scolopendrifolius). Among the putative screened 21 loci, we found only one polymorphic locus for each species. Only one polymorphic locus, detected just one population of each species, revealed significantly high degree of population differentiation between and among populations (F _ST = 0.253 for B. drymoglossum and F _ST = 0.899 for S. scolopendrifolius). These results suggest that genetic drift (consequence of a very small effective population size), coupled with a limited gene flow would play a major role in shaping population genetics of these species in South Korea. The current status of both species (small population sizes, spatially isolated populations, and highly localized habitats) in addition to the extremely low levels of genetic diversity and reckless collection of endangered orchids by plant sellers, significantly threaten the long-term survival of these species in Korea. Conservation of the two species requires both in situ strategies, by introducing of genets to increase effective population sizes by minimizing adverse effects (e.g., outbreeding depression and genetic swamping by non-native genotypes), and ex situ strategies, such as collection of genets from clonal ramets.