Small mammal species turnover in response to climatic variations during the Holocene in Patagonia: A paleolandscape reconstruction

摘要

The goal of this study was to document the effects produced by Holocene climatic changes on the composition of small mammals along the elevational gradient in the Somuncura Plateau Protected Area, northern extra-Andean Patagonia. A bone sequence accumulated by the disintegration of owl pellets was analyzed with taphonomic, paleoecological, and paleoenvironmental purposes. The studied site is located near the boundary between the Southern Monte and the Patagonian Steppes, and the paleontological sequence encompasses the middle Holocene. Multivariate analyses were used to classify Holocene samples into a regional geographical pattern, following the elevational and vegetation gradients. Comparisons between fossil and recent owl pellet samples indicated that species composition differed substantially during the middle Holocene. The species recovered constitutes the current assemblages from the bunchgrass steppes at the higher elevations of the plateau and implies an extension of the Patagonian Steppe occupying areas currently under the Monte influence. This paleoenvironmental context would have been developed under lower temperatures and stronger westerly winds. With temperature as the main factor to the structuring of the small mammal communities in Somuncura, both past and present, special attention must be paid to the design of conservation strategies for this Protected Area considering future scenarios of climate change.