For the last 20 years, Parque Nacional Nahuel Huapi in Argentina has been the site of a comparative study of ecology and genetics of two species of tuco-tuco, a type of burrowing rodent. The June 2011 ongoing eruption of the Puyehue-Cordon Caulle volcanic chain in southern Chile has created a time-sensitive opportunity to assess the impacts of a major geological event on patterns and processes of genetic diversification in natural populations of vertebrates. With extensive pre-eruption data, the proposed post-eruption monitoring will capitalize upon an unprecedented opportunity to explore the effects of a catastrophic environmental event on the population genetics of free-living organisms. Therefore, this study should lead to important new insights into the impacts, including long-term impacts, of volcanic activity, or other catastrophic events, on genetic diversity.
The proposed research supports student training, conservation, and local outreach and education efforts. It will involve undergraduate volunteers from Berkeley, Stanford, and the Universidad Nacional del Comahue in Bariloche, Argentina, thereby providing significant student training. With regard to public outreach, the PIs will maintain web and blog sites on the project, providing quick public access to research methods and results. For the past 20 years, the PIs have worked closely with Administracion de Parques Nacionales Argentinas and other conservation organizations in Patagonia to develop sound, data-based strategies for protecting one of the species of tuco-tuco, including development of the current monitoring and management program. Data generated by the proposed research will contribute to these ongoing efforts.
Determining how organisms respond to changing environments is critical not only to understanding patterns of evolutionary diversification but also – increasingly – to predicting the potential outcomes of global climate change. Catastrophic natural events (e.g., volcanic eruptions) represent one form of environmental change that can have severe impacts on organisms. Because such events are typically unexpected, studying their effects can be challenging due to the frequent absence of detailed pre-catastrophe information. The 2011 eruption of Volcan Puyehue in southern Chile provided a rare opportunity to document the immediate consequences of a catastrophic event on two species of small mammals that are endemic to the area of Patagonia located immediately down wind of Puyehue. Since 1995, the colonial tuco-tuco (Ctenomys sociabilis) and the Patagonian tuco-tuco (C. haigi) have been the subjects of intensive field research aimed at determining why these two closely related species of subterranean rodents – both of which occur in the same habitats in the Limay Valley of southwestern Argentina – display markedly different patterns of behavior and demography. Given this foundation, monitoring of these long-term study populations and their habitats immediately after the Puyehue eruption provided an ideal system in which to characterize the micro-scale changes in ecology and demography associated with this catastrophic natural event. In particular, the ability to couple detailed pre-eruption data on these aspects of biology with immediate post-eruption sampling of the same populations created an unparalleled opportunity to link individual- and population-level responses to potential changes in genetic (i.e., evolutionary) variability. The data obtained indicate that ash fall from Puyehue had marked impacts on the availability of the plant food resources consumed by both study species, resulting in apparent short-term shifts in diet. During the same period, densities for both study populations were significantly reduced, apparently due to the failure of juveniles born the summer before the eruption to survive to adulthood. These effects appeared to be more severe for group-living colonial tuco-tuco than for the solitary Patagonian tuco-tuco, suggesting that the known behavioral and demographic differences between these species may play a role in their response to sudden, severe environmental change. Ongoing data analyses will explore the connections between behavior, demography, and response to change in greater detail. Working in collaboration with researchers at Stanford University, the effects of the eruption on genetic variation in each study population is also being explored. Collectively, these analyses will help to close an important gap in many studies of evolutionary (genetic) response to environmental events in which the event is identified and the resultant changes in genetic structure are documented, but no information is available to determine which population parameters and processes contributed to that response. At the same time, increased understanding of how these processes mediate response to environmental change should facilitate efforts to characterize and, eventually, to predict organismal responses to ongoing patterns of global climate change.
