Effects of landscape fragmentation on genetic diversity of Stipa krylovii roshev (Stipa L.) in agro-pastoral ecotone in Northern China
Stipa krylovii Roshev (Stipa L.) is one of the most important grass species for rangeland ecology and animal husbandry. But some populations of this species are under threat due to landscape fragmentation and habitat isolation resulting from the reclamation and cultivation in ecotone. To determine if and how these disturbances have impacted on genetic structure of S. krylovii populations, an inter-simple sequence repeat (ISSR) markers was used to characterize them for the first time in China. S. krylovii populations from 10 isolated patches were compared with population from unbroken natural rangeland. Eight primers screened were employed to assess genetic diversity within and among populations. The results revealed the total genetic diversity (Ht) and the within population genetic diversity (Hs) were 0.2054 and 0.1388 respectively, while the coefficient of genetic differentiation (Gst) were 0.3241 suggesting more variability within the populations than among them. The cluster pattern of S. krylovii indicated that the populations with larger habitat size were grouped together with CK population in one cluster; likewise, populations with moderate habitat size and smaller area were also grouped together respectively, while the smallest population formed itself into a solo cluster due to genetically different from others. These findings may be early signs of fragmentation effects that in the future will result in species loss even if the present populations are maintained.