BACKGROUND Constraints in migratory capabilities, such as the disruption of gene flow and genetic connectivity caused by habitat fragmentation, are known to affect genetic diversity and the long-term persistence of populations. Although negative population trends due to ongoing forest loss are widespread, the consequence of habitat fragmentation on genetic diversity, gene flow and genetic structure has rarely been investigated in Bornean small mammals. To fill this gap in knowledge, we used nuclear and mitochondrial DNA markers to assess genetic diversity, gene flow and the genetic structure in the Bornean tree shrew, Tupaia longipes, that inhabits forest fragments of the Lower Kinabatangan Wildlife Sanctuary, Sabah. Furthermore, we used these markers to assess dispersal regimes in male and female T. longipes. RESULTS In addition to the Kinabatangan River, a known barrier for dispersal in tree shrews, the heterogeneous landscape along the riverbanks affected the genetic structure in this species. Specifically, while in larger connected forest fragments along the northern riverbank genetic connectivity was relatively undisturbed, patterns of genetic differentiation and the distribution of mitochondrial haplotypes in a local scale indicated reduced migration on the strongly fragmented southern riverside. Especially, oil palm plantations seem to negatively affect dispersal in T. longipes. Clear sex-biased dispersal was not detected based on relatedness, assignment tests, and haplotype diversity. CONCLUSION This study revealed the importance of landscape connectivity to maintain migration and gene flow between fragmented populations, and to ensure the long-term persistence of species in anthropogenically disturbed landscapes.

中文翻译：

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婆罗洲树sh（Tupaia longipes）是热带小哺乳动物的散布和遗传结构，位于马来西亚沙巴Kinabatangan河沿岸的零散景观中。

背景技术迁移能力的限制，例如由栖息地碎片化引起的基因流的破坏和遗传连通性的破坏，会影响遗传多样性和种群的长期持久性。尽管由于森林不断流失造成的人口负增长趋势十分普遍，但很少有人在婆罗洲小型哺乳动物中研究过栖息地破碎对遗传多样性，基因流和遗传结构的影响。为了填补这一知识空白，我们使用了核和线粒体DNA标记来评估居住在沙巴下Kinabatangan野生动物保护区的森林碎片中的婆罗洲树Tu Tupaia longipes的遗传多样性，基因流和遗传结构。此外，我们使用这些标记来评估雄性和雌性长鞭毛虫的扩散方式。结果除了已知的树sh扩散障碍物Kinabatangan河外，沿河岸的异质景观还影响了该物种的遗传结构。具体而言，虽然在北部河岸沿线较大的相连森林碎片中，遗传连通性相对不受干扰，但遗传分化的模式和线粒体单倍型在局部尺度上的分布表明，在南极破碎的江边地区迁移减少了。尤其是，油棕种植园似乎对长柄锥虫的传播产生负面影响。基于相关性，作业测试和单倍型多样性，未检测到明显的性别偏向分散。结论这项研究揭示了景观连通性对于维持零散种群之间迁移和基因流的重要性，