Data from: Ecophysiological variation across a forest-ecotone gradient produces divergent climate change vulnerability within species

Climate change related risks and impacts on ectotherms will be mediated by habitats and their influence on local thermal environments. While many studies have documented morphological and genetic aspects of niche divergence across habitats, few have examined thermal performance across such gradients and directly linked this variation to contemporary climate change impacts. In this study, we quantified variation in thermal performance across a gradient from forest to gallery forest-savanna mosaic in Cameroon for a skink species (Trachylepis affinis) known to be diverging genetically and morphologically across that habitat gradient. Based on these results, we then applied a mechanistic modelling approach (NicheMapR) to project changes in potential activity, as constrained by thermal performance, in response to climate change. As a complimentary approach, we also compared mechanistic projections with climate-driven changes in habitat suitability based on species distribution models of forest and ecotone skinks. We found that ecotone skinks may benefit from warming and experience increased activity while forest skinks will likely face a drastic decrease in thermal suitability across the forest zone. Species distribution models projected that thermal suitability for forest skinks in coastal forests would decline but in other parts of the forest zone skinks are projected to experience increased thermal suitability. The results here highlight the utility of mechanistic approaches in revealing and understanding patterns of climate change vulnerability which may not be detected with species distribution models alone. This study also emphasizes the importance of intra-specific physiological variation, and habitat-specific thermal performance relationships in particular, in determining warming responses.

气候变化相关风险对变温动物（ectotherms）的影响将由生境及其对局地热环境的调控作用所介导。尽管诸多研究已阐明不同生境间生态位分化的形态与遗传特征，但鲜有研究探讨此类环境梯度下的热性能差异，并将该变异直接与当代气候变化影响建立关联。本研究针对喀麦隆境内沿森林至河岸林-稀树草原镶嵌体梯度分布的石龙子（skink）物种Trachylepis affinis展开研究，该物种已被证实沿该生境梯度发生了遗传与形态分化，我们在此量化了其热性能的变异。基于上述研究结果，我们采用机械建模方法（NicheMapR），以热性能为约束条件，预测气候变化背景下该物种潜在活动的变化。作为补充研究手段，我们还将该机械模型的预测结果，与基于森林及交错带石龙子的物种分布模型（species distribution model, SDM）得到的生境适宜性气候驱动变化进行了对比。研究结果显示，交错带石龙子可能从气候变暖中获益，其活动量将有所增加；而森林生境中的石龙子则可能在整个森林区域面临热适宜性的急剧下降。物种分布模型预测表明，沿海森林内石龙子的热适宜性将出现下降，但在森林区域的其他部分，石龙子的热适宜性预计会上升。本研究结果凸显了机械建模方法在揭示和理解气候变化脆弱性模式方面的价值——这类模式仅凭物种分布模型是无法被检测到的。本研究同时强调了种内生理变异，尤其是生境特异性的热性能关系，在决定物种对气候变暖响应过程中的重要性。