Accelerating climate and land-use change are rapidly transforming Earth's biodiversity. While there is substantial evidence on the exposure and vulnerability of biodiversity to global change at the species level, the global exposure of intraspecific genetic diversity (GD) is still unknown. Here, we assess the exposure of mitochondrial GD to mid-21st century climate and land-use change in terrestrial mammal assemblages at grid-cell and bioclimatic region scales under alternative narratives of future societal development. We used global predictions of mammal GD distribution based on thousands of georeferenced mitochondrial genes for hundreds of mammal species, the latest generation of global climate models from the ongoing sixth phase of the Coupled Model Intercomparison Project (CMIP6), and global future projections of land-use prepared for CMIP6. We found that more than 50% of the genetically poorest geographic areas (grid-cells), primarily distributed in tundra, boreal forests/taiga and temperate bioclimatic regions, will be exposed to mean annual temperature rise that exceeds 2°C compared to the baseline period under all considered future scenarios. We also show that at least 30% of the most genetically rich areas in tropical, subtropical and montane regions will be exposed to an increase of mean annual temperature > 2°C under less optimal scenarios. Genetic diversity in these rich regions is also predicted to be exposed to severe reductions of primary vegetation area and increasing human activities (an average loss of 5–10% of their total area under the less sustainable land-use scenarios). Our findings reveal a substantial exposure of mammal GD to the combined effects of global climate and land-use change. Meanwhile the post-2020 conservation goals are overlooking genetic diversity, our study identifies both genetically poor and highly diverse areas severely exposed to global change, paving the road to better estimate the geography of biodiversity vulnerability to global change.

中文翻译：

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哺乳动物遗传多样性对 21 世纪中叶全球变化的影响

加速的气候和土地利用变化正在迅速改变地球的生物多样性。虽然有大量证据表明生物多样性在物种层面对全球变化的暴露和脆弱性，但种内遗传多样性 (GD) 的全球暴露仍然未知。在这里，我们评估了在未来社会发展的替代叙述下，在网格细胞和生物气候区域尺度上，线粒体 GD 对 21 世纪中叶气候和土地利用变化的暴露。我们使用了基于数百种哺乳动物物种的数千个地理参考线粒体基因的哺乳动物 GD 分布的全球预测，这是耦合模型比对项目 (CMIP6) 正在进行的第六阶段的最新一代全球气候模型，以及为 CMIP6 准备的全球未来土地利用预测。我们发现，主要分布在苔原、北方森林/针叶林和温带生物气候区的 50% 以上的遗传最贫困的地理区域（网格单元）将面临与基线相比超过 2°C 的年平均温度升高在所有考虑的未来情景下。我们还表明，在不太理想的情况下，至少有 30% 的热带、亚热带和山地地区遗传最丰富的地区将面临年平均温度升高 > 2°C 的影响。预计这些丰富地区的遗传多样性也将面临主要植被面积的严重减少和人类活动的增加（在不太可持续的土地利用情景下，其总面积平均损失 5-10%）。我们的研究结果揭示了哺乳动物 GD 大量暴露于全球气候和土地利用变化的综合影响。与此同时，2020 年后的保护目标忽视了遗传多样性，我们的研究确定了严重暴露于全球变化的遗传贫乏和高度多样化的地区，为更好地估计全球变化对生物多样性脆弱性的地理分布铺平了道路。