Dipteronia dyerana is a rare endemic from south-eastern Yunnan Province (China) that is known from only five natural populations, two of which occur outside a nature reserve. To obtain base-line information of the population structure, history and conservation of the species, we investigated patterns of genetic diversity within and among all natural populations, in addition to an ex situ conserved population, using inter-simple sequence repeat (ISSR) DNA markers. Across all populations surveyed, average within-population diversity was remarkably low (e.g., 0.088 for Nei's gene diversity), with populations from outside the nature reserve maintaining the highest amounts of genetic diversity. Among all natural populations, high genetic differentiation (GST = 0.375) was detected, together with an isolation-by-distance pattern. Past habitat fragmentation, restricted gene flow and, to a lesser extent, genetic drift are proposed to be the determinant factors responsible for the low genetic diversity and high genetic differentiation observed, although reproductive-ecological factors, such as a mixed-mating system and low seedling recruitment due to inbreeding, might also play a role. We strongly recommend in situ conservation of those D. dyerana populations occurring outside the nature reserve, as they contain the highest proportion of the species' total ISSR fragment diversity, which might be eventually relevant for local adaptation. Our data further indicate that the ex situ conserved population insufficiently represents the genetic diversity present in the species. It is therefore suggested to sample at least four natural populations to cover a reasonable proportion (≥ 95%) of the species' genetic variation for ex situ conservation.
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Document Type: Research Article
Laboratory of Systematic and Evolutionary Botany, Department of Biology, College of Life Sciences, Zhejiang University, Hangzhou 310029, People's Republic of China
Department of Organismic Biology, Salzburg University, 5020 Salzburg, Austria
Yunnan Introduction & Propagation Center for Rare & Endangered Plants, Kunming 650032, People's Republic of China
Publication date: 01 May 2007
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