Landscape genetics in subterranean rodents of the genus Ctenomys: population differentiation associated to highly disturbed habitats from the Pampas region, Argentina.

MATÍAS S. MORA

Gramado

Simposio; 1ª Reunião da ABECO e 5º Simpósio de Ecologia Teórica; 2016

Associação Brasileira de Ciência Ecológica e Conservação (ABECO)

Introduction: Studies of genetic differentiation in fragmented environments help us to identify those landscape features that most affect gene flow and dispersal patterns. Particularly, the assessment of the relative significance of intrinsic biological and environmental factors affecting the genetic structure of populations becomes crucial in ecology and conservation genetics. Objectives: In this study we analyze the population structure and gene flow patterns in the endangered subterranean rodents Ctenomys porteousi, C. australis and C. ?chasiquensis?, three emblematic species of tuco-tucos distributed in small areas in the Pampas region, Argentina. Material and Methods: We use landscape genetics approaches to assess the relationship between genetic connectivity among populations of these species and their environment attributes in their entire distributional ranges using microsatellite markers. Results: In spite of geographical proximity of the sampling sites from C. porteousi and C. australis (8?30 km between the nearest sites) and the absence of marked barriers to individual movement, these species showed strong population structure and low values of gene flow among their populations. In these species, genetic differentiation among sampling sites was consistent with a simple model of isolation by distance, where peripheral areas showed higher population differentiation than those sites located in the central areas of the species? distributions. Particularly, the strongest population genetic structure observed in C. australis seems not to be associated to historical geographic barriers like rivers. C. ?chasiquensis? also showed moderate to high genetic structure at regional level, although this variation was not related to an isolation by distance scheme. Landscape genetic results suggest that some habitat characteristics (such as habitat quality and geographic location) and landscape discontinuities (such as flooded salt flats, agricultural crops and other important human modifications like forest plantations) are important features that shaped the differentiation among populations of these species, at least more intensely than geographic distance. Essentially, landscape genetics analyses show a clear relationship of population structure with habitat quality; in general tuco-tucos prefers sandy soils with low plant cover.Discussion and conclusions: Our results indicate an important genetic structure in all these species, even at a small spatial scale, suggesting that contemporary habitat fragmentation increases their population differentiation. Finally, a close relationship appears to exist between the major climatic episodes occurred during the Late Quaternary in the central region of Argentina and the main historical demographic changes inferred for these species. Excepting for C. australis, the other species appear to be relicts of more extended historical distributions in the Argentinean Pampas in the Late Pleistocene.