Population structure affected by excess gene flow in self-pollinating Elymus nutans and E. burchan-buddae (Triticeae: Poaceae)

• Published in: Population ecology 2010, Vol.52 (1), p.233-241
• Main Authors: Yan, Xue-Bing, Guo, Yu-Xia, Liu, Fa-Yang, Zhao, Chong, Liu, Quan-Lan, Lu, Bao-Rong
• Format: Article
• Language: English
• Subjects: AFLP; Altitude; Behavioral Sciences; Biodiversity; Biomedical and Life Sciences; Ecology; Elymus; Evolutionary Biology; Flowers & plants; Forestry; Gene flow; Genetic differentiation; Genetic diversity; Genetic structure; Genetic testing; Genomes; Geography; Grazing; Life Sciences; Original Article; Pasture; Plant populations; Plant reproduction; Plant Sciences; Plant species; Polymorphism; Population genetics; Population structure; Science; Seed dispersal; Species diversity; Structure of populations; Zoology
• ISSN: 1438-3896; 1438-390X
• DOI: 10.1007/s10144-009-0169-x

Seed-mediated gene flow can considerably affect population genetic structure of strictly self-pollinating species, but little is known on the extent and nature of such gene flow among pastoral plant populations. Molecular fingerprints provide a powerful tool to address the relevant issues. Genetic structure of 22 populations of two self-pollinating pasture species, Elymus nutans and E. burchan-buddae, collected from various altitudes of the Qinghai-Tibetan Plateau was studied using fluorescence-based amplified fragment length polymorphism technique. Analysis of molecular variance revealed 42.97% and 37.63% among-population variation for the two Elymus species, respectively, indicating that the majority of the total variation presented within populations. This result contradicts the common genetic variation pattern for a selfing plant species: lower genetic variation within populations. Further analysis suggested higher level of gene flow among populations within the same region than among different regions across the sampled area for the two Elymus species. STRUCTURE analyses of the Elymus populations indicated an evident admixture genetic structure, particularly among neighboring populations from the same region, supporting the hypothesis of considerable seed dispersal among populations. The excess within-region gene flow of E. nutans and E. burchan-buddae might be caused by grazing animals that promote seed dispersal when moved around the pastoral lands during foraging. The among-population gene flow promulgated by grazing animals may promote the maintenance of genetic diversity in the pasture species, particularly in small and fragmented populations within a given region.