Do landscape and riverscape shape genetic patterns of the Neotropical otter, Lontra longicaudis, in eastern Mexico?

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.