Commensalism facilitates gene flow in mountains: a comparison between two Rattus species

Small mammal dispersal is strongly affected by geographical barriers. However, commensal small mammals may be passively transported over large distances and strong barriers by humans (often with agricultural products). This pattern should be especially apparent in topographically complex landscapes, such as mountain ranges, where valleys and/or peaks can limit dispersal of less vagile species. We predict that commensal species would have lower genetic differentiation and higher migration rates than related non-commensals in such landscapes. We contrasted population genetic differentiation in two sympatric Rattus species (R. satarae and R. rattus) in the Western Ghats mountains in southern India. We sampled rats from villages and adjacent forests in seven locations (20–640 km apart). Capture-based statistics confirmed that R. rattus is abundant in human settlements in this region, whereas R. satarae is non-commensal and found mostly in forests. Population structure analyses using ~970-bp...

小型哺乳动物的种群扩散极易受到地理屏障的制约。然而，与人类共生的小型哺乳动物可借助人类活动（通常伴随农产品运输），被动跨越远距离与强地理屏障。这一现象在地形复杂的区域（如山脉）中尤为显著——山谷与山峰均可限制扩散能力较弱物种的种群扩散。我们预测，在这类地形复杂的景观中，伴生物种相较于其非伴生的近缘物种，将表现出更低的遗传分化水平与更高的种群迁移率。本研究以印度南部西高止山脉（Western Ghats）的两种同域分布鼠类——R. satarae与R. rattus为研究对象，对比了二者的种群遗传分化模式。我们在7个间距为20至640公里的采样点（涵盖村落及其毗邻森林）开展了鼠类采样。基于捕获记录的统计分析证实：该区域内R. rattus在人类聚居区种群数量丰富，而R. satarae为非伴生物种，主要栖息于森林生境中。基于约970 bp的……开展种群结构分析