Phylogeography and Conservation Genetics of the Relic Gymnocarpos przewalskii (Caryophyllaceae) Restricted to Northwestern China

Within-species genetic variation is a fundamental component of biological diversity. An accurate estimate of the level and spatial distribution of genetic diversity of rare and endangered species can provide fundamental information in designing appropriate conservation programs.

Gymnocarpos przewalskii, a rare and endangered species, is restricted to the arid desert areas of northwestern China. It primarily grows in semi-desert steppe, on stony or gravelly sites up to about 2,600 m in altitude.

In the past several decades, G. przewalskii has been subject to rapid demographic decline. For this reason, G. przewalskii was defined as rare and endangered species in the second conservation priority by the China Plant Red Data Book. Nevertheless, up to now, the declining populations of G. przewalskii have not received any special protection. Moreover, the genetic variation, population structure and phylogeographic patterns of this species are still unknown. Such information would help to confirm its endangered status and suggest conservation strategies.

Therefore, using two chloroplast regions (psbA–trnH and ycf6–psbM), together with various population genetic analyses, MA Songmei and Prof. ZHANG Mingli from XIEG conducted phylogeographic study to examine the genetic variation, population structure and evolutionary history of G. przewalskii.

The result indicated that G. przewalskii showed high levels of total genetic diversity (h_T=0.849) and average gene diversity within populations (h_S=0.350). A higher N_ST than G_ST (P<0.001) indicated significant phylogeographic structure across the species range. Nested clade phylogeographic analysis (NCPA) suggested that genetic structure in G. przewalskii has been heavily affected by past fragmentation, which likely resulted from aridity and the expansion of desert in northwestern China during the Quaternary. Mismatch analyses were consistent with NCPA in additionally suggesting contiguous range expansion for populations in the northern Tarim Basin and the Yumen region of Gansu Province, which may have occurred during a less arid interval. Human disturbance was identified as the greatest current threat to the species.

This study was provided by supported by CAS Important Direction for Knowledge Innovation Project (No. KZCX2-EW-305), and Xinjiang Institute of Ecology and Geogeraphy, CAS. The result was published in Conservation Genetics on December 2012, 13(6): 1531-1541.