HOW WILL LIVING CAMELIDS RESPOND TO CLIMATE CHANGE? INSIGHTS FROM THE PALEOECOLOGY OF PLEISTOCENE CAMELIDS

The combination of Pleistocene and extant camelid dietary research and species distributions can help conservationists develop a better understanding of how camelids may respond to future climatic changes. Stable isotope ecology and distribution data can be used to characterize dietary plasticity and preferred habitats of Pleistocene camelids, such as Hemiauchenia and Palaeolama, and extant wild camelids, the guanaco (Lama guanicoe) and vicuña (Vicugna vicugna). We hypothesize that the degree of dietary plasticity and preferred habitat play a crucial role in survival/extinction of camelid genera. Generalists usually fare better than specialists during mass extinctions given their adaptive diets. Stable isotope data indicate that Hemiauchenia was a generalized feeder during the Pleistocene, while Palaeolama was a specialized dense-forest browser. Extant camelids are able to survive in cold, arid environments by using a low metabolism to take advantage of low quality vegetation. Stable isotope data and observational studies suggest that guanacos are highly generalized feeders, while vicuñas are more selective feeders. Not all habitats will be equally affected by climate change, but the predicted decrease in Altiplano habitats will negatively impact camelids. Climate change will force species up the mountains in search of optimal climatic conditions and resources, which will increase the competition at higher elevations. Guanacos will have a greater chance of surviving in marginal habitats due to their generalist diets than the vicuña, which will likely run out of mountain space to move vertically into acceptable habitats. The extinction of Patagonian camels was closely associated with the warm period following the Antarctic Cold Reversal, and the open niche was filled by a different subspecies, the ancestor of the guanaco. As rapid conspecific replacement occurred during the Pleistocene, it is likely that future climate change will create the opportunity for guanacos or other domesticated animals like sheep to fill the vicuña’s niche. The lessons learned from extinct camelids suggest that generalist diets and wide distributions of guanacos will give them a better chance of surviving climatic changes, while the more specialized vicuña will be limited by competition for habitat space and/or resources.