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GEOGRAPHIC DISTRIBUTION AND GENETIC DIFFERENTIATION OF ARTEMISIA SPHAEROCEPHALA

籽蒿的地理分布与遗传分化


对籽蒿(Artemisia sphaerocephala)的分布地点进行了调查,发现了籽蒿在浑善达克沙地的新分布, 绘制了籽蒿的分布图。在籽蒿集中分布的地区取了5个种群,新分布点取了一个种群,利用随机扩增多态性DNA(RAPD)方法进行了遗传分化的研究。15个引物共扩增出255条带,其中多态带232条,多态位点百分率为91%。各种群以乌海流动沙地种群最低, 多态位点百分率为66.7%, 沙坡头种群最高,多态位点百分率为83.4%。籽蒿种群间有着一定的遗传分化,遗传分化系数(Gst)为0.234 8, 表明76.52%的遗传变异存在于种群内。聚类分析显示,籽蒿种群之间的遗传距离与地理距离有着一定的相关性。而相隔很远的浑善达克沙地的锡林浩特种群与毛乌素沙地的榆林种群间的遗传距离较小,且被聚到了一起,表明两个草原区沙地籽蒿种群间的关系密切。

Artemisia sphaerocephala is an extreme xerophytic subshrub and sand dominant species of northwest China. It has important sand binding properties and grows on drifting dunes, semi-drifting dunes and sometimes on fixed dunes in the steppe zone and desert zone. The current distribution range of A. sphaerocephala was investigated. The results show that it is distributed in central and western Inner Mongolia, northwestern Shanxi, northern Shaanxi, northern Ningxia, northern Qinghai, eastern Xinjiang, and Gansu in China and in southern Mongolia and is a Gobi- Mongolia distribution species. A new natural distribution site of A. sphaerocephala was discovered on the Otindag Sandy Land in central Inner Mongolia. The areal map of A. sphaerocephala has been drawn according to the specimens collected in different provinces and based on the literatures. Five populations of A. sphaerocephala were collected from main areas of their distribution and one population was collected from the new distribution site. The six populations were analyzed using random amplified polymorphic DNA (RAPD) markers. A total of 255 loci were obtained from 15 random primers, among which 232 loci were polymorphic. At the species level, the percentage of polymorphic loci was 91%. It showed that genetic polymorphism of A. sphaerocephala was high. The sequence of the percentage of polymorphic loci of the six populations was: Shapotou (SHPT) 83.4% >Yulin (YL) 75.3% >Azuoqi (AZQ) 74.1% >Wuhai fixed dune (WH2) 72.4%>Xilinhot (XLHT) 68.8%>Wuhai drifting dune (WH1) 66.7%. This sequence was slightly different from Shannon‘s diversity index. The latter was: SHPT>YL>AZQ>XLHT>WUH2>WUH1. The sequence of Nei‘s gene diversity was the same as the sequence for Shannon‘s diversity index. The genetic differentiation among populations (Gst) was 0.234 8 indicating that there was genetic differentiation among populations, but 76.52% of this variation existed within the populations. According to the results of cluster analysis based on Nei‘s genetic distances, correlations existed between genetic distances and geographical distances. However, for the Xilinhot population of Otindag Sandy Land and Yulin population of Mu Us Sandy Land, the geographical distances were far and genetic distances were close, indicating that there was a close connection between the populations on these two sandy lands of grassland regions. It is highly likely that A. sphaerocephala of Otindag Sandy Land came from Mu Us Sandy Land.