The population genetic structure and diversification of Aristolochia delavayi (Aristolochiaceae), an endangered species of the dry hot valleys of the Jinsha River, southwestern China

Aristolochia delavayi Franch. is an endangered species of the dry hot valleys of the Jinsha River, southwestern China. The genetic diversity and structure of the species and the occurrence of gene flow were investigated with eight inter-simple sequence repeat (ISSR) markers and four plastid loci (matK, trnL-trnT, rps4-trnT, and trnC-rpoB). The analysis of ISSR markers indicated that the genetic diversity of the species is relatively high (PPB = 84.71%). Similarly, a high gene diversity of H-T = 0.833 was found based on the four plastid loci. It is possible that this species previously maintained a large effective population size and that the current relict distribution of the species is a result of large-scale fragmentation and habitat destruction. The origin of the species at approximately 3.407 million years ago and the ensuing intraspecific divergence are generally consistent with the history of two major glaciations in this region. Conservation measures are urgently needed to increase the genetic diversity and population size of this species through both in-and ex-situ action.