青南高原地区高原鼠兔棘球蚴的分子鉴定和遗传分化分析

Molecular Identification and Genetic Variations of Echinococcus in Plateau Pika from Eastern and Southern Qinghai, China

基于线粒体coxl基因部分序列对青南高原地区称多、达日、玛沁3县高原鼠兔感染的20份棘球绦虫幼虫（棘球蚴）样品进行分子鉴定和遗传分化分析。在测序获得的700bp长度序列中检测到17个变异位点，其中11个为简约信息位点。共检测到9个单倍型，最大简约法和最大似然法都表明这些单倍型都属于石渠棘球绦虫。遗传距离和聚类分析显示，称多和达日种群遗传距离最近，而玛沁种群与称多、达日以及首次报道的石渠县样本的遗传关系较远，此外玛沁种群的遗传多样性要高于其他2个种群，推测玛沁地区可能是青南地区石渠棘球绦虫的起源地之一。单倍型谱系关系分析显示，所有单倍型以及之前报道（Xiaoeta1．，2005）的石渠县样本以Hl为中心形成辐射状结构，这与前人的研究结论即石渠棘球绦虫单倍型呈现链状结构相反，显示出石渠棘球绦虫遗传分化规律的复杂性。

Based on mitochondrial coxl gene, we analyzed the taxonomic status and genetic variations of 20 Echinococcus samples in plateau pika from Chengduo （CD） , Dari （DR） and Maqin （MQ） in eastern and southern Qinghai, China. From the sequenced 700 bp sequences, we detected 17 variable sites, in which 11 were parsimony informative sites. We identified nine haplotypes, all of which were E. shiquicus based on maximum parsimony and maximum likelihood analyses. CD and DR had a closer relationship than among other populations, while MQ had a far phylogenetic relationship from CD, DR and Shiqu （SQ, where E. shiquicus was first reported）; moreover, MQ had higher genetic diversities than CD and DR, suggesting that MQ might be one of the origins in the eastern and southern Qinghai region. The statistical parsimony networks of E. shiqtticus haplotypes showed a star-like expansion from a main founder haplotype, which was different from the former study showing a divergent network, indicating that the E. shiquicus might have a more complex historic genetic variation process than expected.