岛屿生境下黄毛鼠种群的遗传变异

岛屿具有独特的生态系统,常被生态学家和进化生物学家视为研究生物进化的天然实验室,岛屿生物地理学也受到了越来越多科学家的关注。对舟山群岛8个面积不等岛屿的黄毛鼠(Rattus losea)种群进行了调查,分析了8个种群的遗传变异特征,对探讨岛屿理论中的种群动态和种群分化具有重要意义。采用线粒体分子标记技术,利用PCR扩增得到D-loop区基因序列815 bp,在330个黄毛鼠样本中共识别出15个单倍型,平均核苷酸多样性(P_i)为0.001,平均单倍型多样性(H_d)为0.364,表明舟山群岛黄毛鼠种群的遗传多样性较低。Tajima′s D中性检验显示除了小盘峙种群,均为显著负值(P0.01),表明种群受到了自然选择的作用,历史上发生过种群扩张。AMOVE显示,群体间的遗传分化指数平均值为0.745,处于较高的分化水平,表明遗传变异主要来自种群间,占74.5%。基于线粒体D-loop区序列构建的系统发育树和中值网络都表明8个岛屿的黄毛鼠种群起源于两个母系。此外,Mental检验显示不同岛屿种群间的遗传距离与岛屿间地理距离之间存在显著正相关关系(r=0.6077,P=0.004),种群遗传多样性与岛屿面积并未发现显著相关性(r=0.6255,P=0.1840)。研究结果可为岛屿黄毛鼠种群的微观演化以及一些岛屿物种的进化理论提供参考。

Genetic variation of Rattus losea populations in island habitats

With the unique ecosystems, islands are often regarded as natural laboratories for studying biological evolution by ecologists and evolutionary biologists. In recent years, the increasing number of scientists have paid attentions to island biogeography. In this study, the genetic variation characteristics were analyzed for Rattus losea populations in 8 islands with different area and distance in Zhoushan archipelago, which is of great significance to study the population dynamics and population differentiation of island rule. Mitochondrial molecular marker technique was used to obtain the 815 bp D-loop region sequence by PCR. A total of 15 haplotypes were identified in 330 samples. The average nucleotide diversity (P_i) was 0.001 and the average haplotype diversity (H_d) was 0.364, which revealed that the genetic diversity of Rattus losea populations in Zhoushan Archipelago had a low level. The Tajima''s D neutral test showed that the parameters of the populations were negative values except for XPZ population (P < 0.01), indicating that the populations were naturally selected and experienced the population expansion. AMOVA results showed that the average genetic differentiation index (74.5%) among populations was at a higher level, indicating the genetic variation mainly occurred in the populations. Phylogenetic tree and median network constructed on the basis of mitochondrial D-loop region sequences indicated that the 8 Rattus losea populations originated from two matrilinear systems. Beside, the results of mental test results showed that there was a significantly positive correlation between genetic distance and geographic distance (r=0.6077, P=0.004), and no significant correlation was found between genetic diversity and island area (r=0.6255, P=0.1840). The results can be used as a reference for the microevolution of Rattus losea populations and the evolution theory of some island species.