Genetic diversity and geographic differentiation in endangered Ammopiptanthus (Leguminosae) populations in desert regions of northwest China as revealed by ISSR analysis

Abstract

• Background and Aims: The desert legume genus Ammopiptanthus comprises two currently endangered species, A. mongolicus and A. nanus. Genetic variability and genetic differentiation between the two species and within each species were examined. • Methods: Inter-simple sequence repeat (ISSR) marker data were obtained and analysed with respect to genetic diversity, structure and gene flow. • Key Results: Despite the morphological similarity between A. mongolicus and A. nanus, the two species are genetically distinct from each other, indicated by 63 % species-specific bands. Low genetic variability was detected for both population level (Shannon indices of diversity Hpop = 0.106, percentage of polymorphic loci P = 18.55 % for A. mongolicus; Hpop = 0.070, P = 12.24 % for A. nanus) and species level (Hsp = 0.1832, P = 39.39 % for A. mongolicus; Hsp = 0.1026, P = 25.89 % for A. nanus). Moderate genetic differentiation was found based on different measures (AMOVA ΦST and Hickory θB) in both A. mongolicus (0.3743-0.3744) and A. nanus (0.2162-0.2369). • Conclusions: The significant genetic difference between the two species might be due to a possible vicariant evolutionary event from a single common ancestor through the fragmentation of their common ancestor's range. Conservation strategies for these two endangered species are proposed. © The Author 2005. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved.