Janzen's influential “mountain passes are higher in the tropics” hypothesis predicts restricted gene flow and genetic isolation among populations spanning elevational gradients in the tropics. Few studies have tested this prediction, and studies that focus on population genetic structure in Southeast Asia are particularly underrepresented in the literature. Here, we test the hypothesis that mountain treeshrews (Tupaia montana) exhibit limited dispersal across their broad elevational range which spans ~2,300 m on two peaks in Kinabalu National Park (KNP) in Borneo: Mt Tambuyukon (MT) and Mt Kinabalu (MK). We sampled 83 individuals across elevations on both peaks and performed population genomics analyses on mitogenomes and single nucleotide polymorphisms from 4,106 ultraconserved element loci. We detected weak genetic structure and infer gene flow both across elevations and between peaks. We found higher genetic differentiation on MT than MK despite its lower elevation and associated environmental variation. This implies that, contrary to our hypothesis, genetic structure in this system is not primarily shaped by elevation. We propose that this pattern may instead be the result of historical processes and limited upslope gene flow on MT. Importantly, our results serve as a foundational estimate of genetic diversity and population structure from which to track potential future effects of climate change on mountain treeshrews in KNP, an important conservation stronghold for the mountain treeshrew and other montane species.

中文翻译：

---

婆罗洲流行小哺乳动物在陡峭的生态梯度上的遗传结构很少。

詹森（Janzen）具有影响力的“热带山脉通行率较高”的假说预测，跨越热带海拔梯度的人群之间的基因流和遗传隔离受到限制。很少有研究检验这一预测，而文献中对东南亚人口遗传结构的研究尤其不足。在这里，我们检验了山上树h（Tupaia montana）在婆罗洲的京那巴鲁国家公园（KNP）的两个峰上跨越〜2,300 m的宽广海拔范围内散布有限，分别是坦布育空山（MT）和京那巴鲁山（MK）。我们在两个峰的不同高度上对83个个体进行了采样，并对来自4,106个超保守元件位点的有丝分裂基因组和单核苷酸多态性进行了人口基因组分析。我们检测到了弱的遗传结构，并推断了跨越海拔和峰之间的基因流。我们发现MT的遗传分化比MK更高，尽管它的海拔和相关环境变化较低。这暗示着，与我们的假设相反，该系统中的遗传结构并非主要由高度决定。我们建议，这种模式可能是历史过程和MT上有限的向上基因流的结果。重要的，