Abstract
BackgroundThe main goal of this contribution was to define the ecological niche of the guanaco (Lama guanicoe), to describe potential distributional changes, and to assess the relative importance of niche conservatism and divergence processes between the two lineages described for the species (L.g. cacsilensis and L.g. guanicoe).MethodsWe used maximum entropy to model lineage’s climate niche from 3,321 locations throughout continental Chile, and developed future niche models under climate change for two extreme greenhouse gas emission scenarios (RCP2.6 and RCP8.5). We evaluated changes of the environmental niche and future distribution of the largest mammal in the Southern Cone of South America. Evaluation of niche conservatism and divergence were based on identity and background similarity tests.ResultsWe show that: (a) the current geographic distribution of lineages is associated with different climatic requirements that are related to the geographic areas where these lineages are located; (b) future distribution models predict a decrease in the distribution surface under both scenarios; (c) a 3% decrease of areal protection is expected if the current distribution of protected areas is maintained, and this is expected to occur at the expense of a large reduction of high quality habitats under the best scenario; (d) current and future distribution ranges of guanaco mostly adhere to phylogenetic niche divergence hypotheses between lineages.DiscussionAssociating environmental variables with species ecological niche seems to be an important aspect of unveiling the particularities of, both evolutionary patterns and ecological features that species face in a changing environment. We report specific descriptions of how these patterns may play out under the most extreme climate change predictions and provide a grim outlook of the future potential distribution of guanaco in Chile. From an ecological perspective, while a slightly smaller distribution area is expected, this may come with an important reduction of available quality habitats. From the evolutionary perspective, we describe the limitations of this taxon as it experiences forces imposed by climate change dynamics.
Highlights
Since industrialization, the anthropogenic influence on natural environments has soared and human induced climate change is imposing severe challenges to the equilibrium of natural ecosystem functioning (IPCC, 2013)
Based on the latest projections of climate change in the region (Rojas, 2012; IPCC, 2013) and the understanding of L. guanicoe taxonomy and life history, we developed models based on niche theory to assess the impact of climate change on guanaco’s evolutionary significant units (ESUs)
The major contribution to the current distribution of L. guanicoe is given by the annual range of temperature (28.2%, AUC = 0.84), whereas L. g. cacsilensis is dominated by precipitation seasonality (66.7%, AUC = 0.95), the contact population by annual precipitation
Summary
The anthropogenic influence on natural environments has soared and human induced climate change is imposing severe challenges to the equilibrium of natural ecosystem functioning (IPCC, 2013). A similar situation happens when comparing projected niches under the worst climate change scenario (RCP8.5) In such latter case, our results suggest that L.g. guanicoe will closely resemble the future climatic niche of the contact population, but this population shows no similarity to the southern lineage. Second and third columns indicates compared lineages and focal lineage used for the comparison This test generates new models for the compared lineages, using the set of climatic variables defined in this work, but omitting the climatic space where the niche of the “background species” is located. In this way, it is modeled in the background area with the occurrence of the focal species.
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