Phylogeography and landscape genetics in the subterranean rodents of the genus Ctenomys

Abstract

The spatial distribution of the genetic polymorphisms in natural populations depends on the spatial and temporal scales of the underlying evolutionary and geological processes. While phylogeographic approaches focus on population genetics at broader time scales, landscape genetics emphasize on how landscape characteristics and environmental variables have shaped gene flow patterns and connectivity among demes or populations. In this chapter we present an exhaustive review of all the studies in phylogeography and landscape genetics in the subterranean rodents of the genus Ctenomys (commonly known as tuco-tucos), covering different geographical regions in the Southern South America. These subterranean rodents are strongly associated with the type of habitat that they occupy, such that the historical demography of these species has been largely impacted by the evolution of environments and landscapes. The glacial-interglacial cycles of the Late Quaternary have strongly molded the distribution and demography of these species, especially the climatic and environmental changes occurred in the Pleistocene-Holocene boundary. In this context, we observed that some species of this genus have similar phylogeographic patterns. Several species adjust to an IBD pattern, suggesting that the populations have remained stable long enough to achieve a balance between genetic drift and migration. In contrast, some species have suffered recent demographic processes that profoundly impacted the distribution of genetic variation. We continue with some considerations on how genetic variation recovers after demographic change events, and how the founder events impact on genetic diversity in edge populations. We close with a brief overview on how environmental and landscape features structure genetic variation of populations, and with some comments on conservation genetics considering species with wide and narrow distributions.