Data for habitat quality or quantity? Niche marginality across 21 plants and animals suggests differential responses between highland and lowland species to past climatic changes

Climatic changes can affect species distributions, population abundance, and evolution. Such organismal responses could be determined by the amount and quality of available habitats, which can vary independently. In this study, we assessed changes in habitat quantity and quality independently to generate explicit predictions of the species’ responses to climatic changes between Last Glacial Maximum (LGM) and present day. We built ecological niche models and distribution models for 21 reptile, mammal, and plant taxa from the Baja California peninsula inhabiting lowland or highland environments. Geological data suggests the CCSM global circulation model is a better representation of LGM climate for the Baja California peninsula. Significant niche divergence was detected for all clades within species, along with significant differences in the niche breadth and area of distribution between northern and southern clades. Most clades showed a reduction in distribution area towards LGM. Further, niche marginality (used as a measure of habitat quality) was higher during LGM for most clades, except for northern highland species. Our results suggest that changes in habitat quantity and quality can affect organismal response independently. This allows the prediction of genomic signatures associated with changes in effective population size and selection pressure that could be explicitly tested to support our models.

气候变化可影响物种分布、种群丰度与演化进程。此类生物响应可由可利用栖息地的数量与质量决定，且二者的变化互不相关。本研究独立评估了栖息地数量与质量的变化，以明确预测物种在末次盛冰期（Last Glacial Maximum, LGM）与现代之间对气候变化的响应。我们针对下加利福尼亚半岛栖息于低地或高地环境的21个爬行类、哺乳类及植物类群，构建了生态位模型与分布模型。地质数据表明，全球环流模型（CCSM）可更精准地复现下加利福尼亚半岛的末次盛冰期气候。研究检测到物种内所有演化支均存在显著的生态位分化，且南北演化支的生态位宽度与分布面积存在显著差异。多数演化支的分布面积在末次盛冰期时有所缩减。此外，除北部高地物种外，多数演化支在末次盛冰期的生态位边缘性（用于衡量栖息地质量）更高。本研究结果表明，栖息地数量与质量的变化可独立影响生物响应。据此可预测与有效种群大小及选择压力变化相关的基因组特征，后续可通过实验明确验证以支撑本研究构建的模型。