梭沙韭和昌都韭的遗传变异和生态位分化

Genetic variation and niche differentiation of Allium forrestii and Allium changduense

选取葱属(Allium L.)的两个近缘类群,梭沙韭(Allium forrestii Diels)和昌都韭(A.changduense J.M.Xu.)共16个居群232个个体,基于3个叶绿体基因片段序列(atp IatpH、trn L-trn F和ndh C-trn V)进行遗传变异和生态位分化研究。野外调查发现,两物种分布间断,生境有明显的差异;遗传变异分析结果表明,梭沙韭和昌都韭既没有共享单倍型,也不存在明显基因流,支持两个种是独立进化的观点;生态位分析显示,梭沙韭和昌都韭的最适生态位基本重叠,只有温度季节性变化和最冷季平均温度差别较大。推测,剧烈的温度变化和较低的冬季均温以及高度特异性的生境可能是昌都韭与梭沙韭分化的重要原因。

In this study, genetic variation and niche differentiation of two closely related speciesAllium forrestii Diels andA. changduense J. M. Xu were investigated based on three chloroplast DNA regions （atpI-atpH,trnL-trnF and ndhC-trnV）. Fresh leaves from 232 individuals of 16 natural populations were collected. Field investigation showed that the distributions of the two species were discontinuous, with substantial differences in their habitats. According to the results from analysis of genetic variation, neither shared haplotype nor obvious gene flow was detected between those two species, indicating the independent evolution of the two species. The results of ecological niche modeling showed that the optimum ecological niche of both species were overlapped, except for the temperature seasonality and the mean temperature of coldest season. Our results indicated that the extreme temperature seasonality, lower mean temperature of coldest season, and highly specific habitat may be the major reasons for the differentiation of A. forrestiiandA. changduense.