Genetic diversity and population structure of the endangered alpine quillwort Isoetes hypsophila (Isoetaceae) revealed by SSR analysis

Isoetes hypsophila Hand.-Mazz. (Isoetaceae) is an endangered alpine quillwort endemic to the Qinghai-Tibetan Plateau (QTP). A total of 247 individuals of L hypsophila from 11 populations were analyzed using ten pairs simple sequence repeats (SSR) markers. Seventy-seven alleles were recorded, with an average of 7.7 alleles per locus (ranging from 3 to 12) and the expected heterozygosity (H-E) ranged from 0.392 to 0.536 (average 0.471). Clear population structure among I. hypsophila populations was found and the proportion of genetic differentiation among populations accounted for about 20% of total genetic diversity (F-ST = 0.178; probability of allelic co-ancestory F-coal = 0.238). This genetic structure was probably due to limited gene flow hindered by complex terrains, bottlenecks resulting from water fluctuation in habitats, and repeated population retreat and recolonization during the ice ages. In conservation, four management units corresponding to four geographic regions were suggested, and the populations from different management units with higher genetic variation should be the priority targets of both in situ and ex situ conservation. (C) 2012 Elsevier Ltd. All rights reserved.