Estimating genetic and demographic parameters relevant for the conservation of the Neotropical otter, Lontra longicaudis, in Mexico

Abstract

Habitat deterioration and fragmentation increase the risk of wildlife extirpation as they have strong impacts on population size, genetic diversity and gene flow. Small populations are more susceptible to these factors because the loss of genetic diversity by drift and inbreeding occurs at faster rates. Therefore, estimates of genetic diversity and population sizes of threatened and small wildlife populations in deteriorated landscapes are critical for managing and conservation. Here, we used a non-invasive sampling approach in combination with eleven microsatellite loci to evaluate genetic diversity, genetic structure, and demographic parameters of the Neotropical otter (Lontra longicaudis) in three river basins (Actopan, La Antigua and Jamapa), which are priority conservation areas for Veracruz, Mexico. Our results revealed moderate genetic diversity and genetic structure among river basins. However, we detected first-generation migrants among basins, suggesting current gene flow. Effective population size for each basin was considerably lower than the value (Ne < 100) suggested to maintain genetic variation of populations in the short-term. Similarly, census population size was lower than estimates reported for L. longicaudis in a conserved region in Mexico. We did not find evidence of recent genetic bottlenecks for any basin. Our genetic and demographic results suggest that L. longicaudis in the three river basins could be experiencing genetic isolation and erosion, with La Antigua being the most vulnerable basin. Natural fragmentation and habitat deterioration seem to be shaping the observed patterns of genetic variation in the Neotropical otter.