The first assessment of genetic diversity, population structure, and historical population dynamics of Myocastor coypus

IBAÑEZ, EZEQUIEL ALEJANDRO; PERALTA, DIEGO M.; OBREGÓN, GRACIELA; NARDELLI, MAXIMILIANO; TÚNEZ, JUAN IGNACIO

Congreso; II Congreso Latinoamericano de Genética para la Conservación; 2021

REGENEC

Myocastor coypus is a native rodent of South America strongly linked to river systems. In their native distribution range, the studies carried out were mainly aimed at studying its ecology and parasitic status, but genetic studies are very limited. Here, we used sequences of the mitochondrial D-loop control region to study the genetic diversity, population genetic structure, and some aspects of historical population dynamics of coypu in the centre of its distribution range. Our work was focused on a portion of this extensive region, particularly in the Río Arrecifes, Río Luján and Arroyo de la Cruz basins. Our results showed moderate to high levels of haplotype diversity (H: 0.500 - 0.972) and low values of nucleotide diversity (π: 0.001 – 0.016). The AMOVA grouping populations by river basins showed a lack of genetic structure in the study area (ФST = 0.041; P > 0.001). Pairwise differences of ФST values between sampling sites did not show significant differences between them. In addition, correlations among the genetic distance and the Euclidean or river corridor geographical distances between sampling sites were not significant. Also, the Bayesian assignment test showed the existence of two haplogroups distributed in most sampling sites, and only two haplotypes present in the same sampling site were not assigned of any haplogroup. These results suggest the movement of coypu would be independent of the structure of current known river networks and its dispersal patterns would be related to flooding events and the presence of lagoons connecting river basins. The demographic expansion patterns in this coypu population and other populations of South American mammals during the Late Pleistocene, support the hypothesis that climatic fluctuation and ecological changes are related to demographical changes in wild populations. This is the first study using non-invasive sampling in native coypu populations, and mitochondrial data obtained constitute the first record in the species native distribution range. The results obtained in this work have potential conservation and management implications and provide new insights into the understanding of those factors that preserve genetic diversity and gene flow in freshwater habitats. Future studies where are included more sampling sites and the use of nuclear markers will surely provide better estimates of genetic diversity and population structure of coypu, including historical and current changes in gene flow patterns and possible isolation of populations due to human impact in freshwater ecosystems.