High genetic diversity and low genetic differentia- tion in the relict tree fern Sphaeropteris brunoniana (Cyatheaceae) revealed by amplified fragment length polymorphism (AFLP)

Amplified fragment length polymorphism (AFLP) was employed to analyze the population genetics of relict tree fern Sphaeropteris brunoniana. A total of 132 individuals from ten natural populations in China and Laos were collected for this study. Using two selective primers, 234 reliable bands were generated, of which 221 (94.4%) were polymorphic. Genetic analysis indicated an unexpectedly high level of genetic diversity in S. brunoniana (Ht= 0.333, Hsp= 0.499), but a low level of genetic differentiation among populations (Gst= 0.16, φST= 0.12 and (Hsp-Hpop)/Hsp= 0.16). This result may be due to its life traits, evolutionary history and gene flow. Two major genetic groups, one from Yunnan and the other from Hainan-Laos, were detected among the ten investigated populations. The Mantel test correlated this differentiation with geographic distance. However, the different population origins may also have an effect on this differentiation. Based on these findings, implications for conservation strategies of this species in China are discussed.