Genetic variation in the endemic plant Cycas debaoensis on the basis of ISSR analysis

Cycas debaoensis Y. C. Zhong et C. J. Chen is a rare and endangered cycad species that is endemic to South China. It has divided pinnae. Genetic variation in the species was investigated by using an intersimple sequence repeat (ISSR) marker. The species exhibits a moderate level of genetic diversity ( at population level P = 34.7%, H = 0.141, I = 0.204; at species level P = 57.4%, H = 0.215, I = 0.315) and a high level of genetic differentiation among populations (G(st) = 0.342). Thus, the indirect estimate of gene flow on the basis of G(st) was low (N-m = 0.481). The narrow colonisation area and island pattern of distribution, combined with limited gene flow among populations and genetic drift, may play an important role in shaping the genetic structure of C. debaoensis. On the basis of these findings, strategies are suggested for the conservation and management of the species.