Genetic variation and clonal diversity of the endangered aquatic fern Ceratopteris pteridoides as revealed by AFLP analysis

Ceratopteris pteridoides (Hook.) Hieron. is an endangered aquatic homosporous fern in China. Genetic diversity and structure of eight populations collected from the mid-lower reaches of Yangtze River were investigated using amplified fragment length polymorphisms (AFLPs). A low level of gene diversity was found at the population level (P_p = 17.4%, H_E = 0.039 and I = 0.063), which possibly resulted from its high degree of inbreeding, clonal growth and short life history of this species. C. pteridoides contained high clonal diversity (PD = 0.757, D = 0.992). High population differentiation was revealed by partitioning of genetic diversity (G_ST = 0.707), and the AMOVA analysis consistently showed that 72.3% of the total genetic diversity was attributable to among-population diversity. Based on the genetic information from UPGMA cluster and principal coordinate analysis, two management units have been identified, and translocation within each management unit is recommended.