Modeling Past, Present and Future niches: Species-specific responses to climate changes in three shrub congeners from South American drylands

Abstract

AbstractContext Climate and land use change threat biodiversity and impact on natural and anthropogenic systems as well, in all continents. Although these effects are deepened in regions beholding highly adapted species to particular environmental conditions, like drylands in the Global South, surprises the scarcity of studies exploring the impact of climatic forces across time in these regions. Objectives Our aim is to assess the spatial distribution and niche overlap of three dominant native shrubs of the Monte Desert under present climate conditions, to retrodict their potential past distribution, and anticipate their predicted range under future climate scenarios, to complement traditional approaches of biodiversity conservation and sustainability. These species areLarrea cuneifolia(LC),L. divaricata(LD), andL. nitida(LN) that span between 15 and 45°S latitude. They are key elements of the largest temperate dryland of South America, and are alternative forage for livestock. Methods We used ecological niche modeling and niche overlap approaches, which we then projected to past (Last Glacial Maximum LGM and Mid Holocene) and future (2050 and 2070) under two scenarios of greenhouse gas emissions and consequent climate change: Representative Concentration Pathway (RCP) 4.5 and 8.5, representing medium-to-low and high emissions levels, respectively. We evaluated these scenarios according to different global circulation models (GCMs) (CCSM4 and MIROC-ESM), to allow detailed assessment of uncertainty in model predictions. Results All species showed high niche overlap in the present (67–89%), and when projecting the models, we observed thatLCandLDwould have reached maximum suitability in the Mid Holocene and would remain stable by 2050. However,LCwould gain andLDwould loss suitability by 2070. Meanwhile,LNwould have reached the maximum suitability in the LGM, which decreased in the Holocene, increased in the present and projects a severe reduction in the future. Conclusion We found species-specific responses even among species with current overlapping niches such asLCandLD, highlighting the need to develop mitigation measures particularly forLDandLNin the face of climate change and land use pressures. Global South deserts are being highly degraded and information on future potential ranges of endemic species can support the development of sustainable conservation and management plans.