Genetic variation and conservation of Changnienia amoena, an endangered orchid endemic to China

Changnienia amoena is a diploid and self-compatible orchid endemic to China. This species is in great danger of extinction with its current distribution being highly fragmented and discontinuous. This study investigated the level and apportionment of genetic diversity of this species using RAPD technique. Based on 119 discernible DNA fragments generated by 16 primers, an intermediate level of genetic diversity was found at the species level with the percentage of polymorphic bands (P) of 76.5%, expected heterozygosity (He) of 0.194. However, the genetic diversity at the population level was significantly lower (P=37.2%, He=0.120) compared with the average of other species with similar life history characteristics. A high level of population differentiation was detected with 43.8% variation resided among populations as measured by AMOVA. It is noteworthy that as much as 49.2% of the total diversity could be attributed to difference among populations when five populations from an area of approximately 60 x 25 km in the Xinning County were considered. These results, in conjunction with other evidence from pollination and ecological studies, suggest that the low within-population but high among-population variation in C. amoena is likely due to the small population sizes and local extinction because of habitat destruction and loss. The restricted gene flow is probably another factor contributing to the genetic structure found in C. amoena. Based on these findings, we proposed conservation managements for this endangered species, including habitat protection along with the protection of their pollinators, artificial pollination as well as ex situ conservation.