Preliminary genetic assessment of a Lontra longicaudis population located in the Southern border of its biogeographical distribution

TRIGILA AP; CASSINI MH.; TÚNEZ JI.

Río de Janeiro

Congreso; XII IUCN OSG International Otter Congress; 2014

IUCN Otters Specialists Group

We conducted a genetic study of a population of Neotropical otters, Lontra longicaudis, in the lower portion of the Paraná Delta. This Delta is located in the East-Center of Argentina and it represents part of the southern limit of the distribution of this species. It is one of the most important wetlands in Argentina, as it possesses a high fauna and flora richness. Nevertheless, this wetland is exposed to habitat fragmentation, degradation and other anthropogenic threats. We collected scat samples from several localities, which differed in their degree of anthropogenic impact. Thereafter, we extracted the total DNA and conducted genetic analyses with primers for microsatellites developed for other otter species (Lut782, 04OT05, 04OT04, RIO11, RIO7, Lut701, 04OT02, 04OT22, Lut733). We first tested the alleles for Hardy-Weinberg equilibrium and genetic linkage disequilibrium. We finally estimated the genetic diversity of the population by calculating the observed (Ho) and expected heterozygosity (He), the number of alleles per locus and the size of the alleles. We found that the microsatellite selected were informative in L. longicaudis. The Ho was 0.56 and the He was 0.52 and the number of alleles per locus was 4.88. The genetic diversity was the lowest found compared with all the previous published studies for the species. This result is predicted by the central-marginal hypothesis. It proposes that populations located in the periphery of the biogeographical distribution should exhibit low genetic diversity as a consequence of smaller effective population size and greater geographical isolation. Our results directly provide new insight into the conservation of the species and indirectly to the riparian habitats where it lives.