Context Functional connectivity of semiaquatic species is poorly studied despite that freshwater ecosystems are amongst the most threatened worldwide due to habitat deterioration. The Neotropical otter, Lontra longicaudis , is a threatened species that represents a good model to evaluate the effect of landscape-riverscape features on genetic structure and gene flow of freshwater species. Objectives We aimed to assess the spatial genetic structure of L. longicaudis and to evaluate the landscape-riverscape attributes that shape its genetic structure and gene flow at local sites (habitat patches) and between sites (landscape matrix). Methods We conducted the study in three basins located in Veracruz, Mexico, which have a high degree of ecosystem deterioration. We used a non-invasive genetic sampling and a landscape genetics individual-based approach to test the effect stream hierarchical structure, isolation-by-distance, and isolation-by-resistance on genetic structure and gene flow. Results We found genetic structure that corresponded to the latitudinal and altitudinal heterogeneity of the landscape and riverscape, as well as to the hierarchical structure of the streams. Open areas and steep slopes were the variables affecting genetic structure at local sites , whereas areas with suitable habitat conditions, higher ecosystem integrity and larger streams enhanced gene flow between sites . Conclusions The landscape-riverscape characteristics that maintain functional connectivity of L. longicaudis differed between the upper, middle, and lower basins. Our results have important implications for the conservation of the species, including the maintenance of larger suitable areas in Actopan and the necessity to improve connectivity in Jamapa, through the establishment of biological corridors.

中文翻译：

---

墨西哥东部的新热带水獭 Lontra longicaudis 的遗传模式是否会塑造景观和河流景观？

背景 尽管由于栖息地恶化，淡水生态系统是世界上受威胁最严重的生态系统之一，但对半水生物种的功能连通性的研究却很少。新热带水獭 Lontra longicaudis 是一种受威胁物种，是评估景观-河流景观特征对淡水物种遗传结构和基因流影响的良好模型。目标我们旨在评估 L. longicaudis 的空间遗传结构，并评估塑造其遗传结构和基因流的景观-河流景观属性，这些属性在局部地点（栖息地斑块）和地点之间（景观矩阵）。方法 我们在位于墨西哥韦拉克鲁斯的三个盆地进行了研究，这些盆地的生态系统恶化程度很高。我们使用非侵入性遗传采样和基于景观遗传学个体的方法来测试效应流层次结构、距离隔离和电阻隔离对遗传结构和基因流的影响。结果我们发现了与景观和河流景观的纬度和高度异质性以及溪流的层次结构相对应的遗传结构。开阔地和陡坡是影响当地基因结构的变量，而栖息地条件合适、生态系统完整性较高和河流较大的地区会增强地点之间的基因流动。结论 上、中、下流域维持长尾螟功能连通性的景观-河流景观特征不同。