Table_2_Differential Adaptive Potential and Vulnerability to Climate-Driven Habitat Loss in Brazilian Mangroves.XLSX

Geographic and environmental differences have been identified as factors influencing Brazilian mangrove trees' genetic diversity. Geographically, distinct species have convergent spatial genetic structures, indicating a limited gene flow between northern and southern populations. Environmentally, genomic studies and common garden experiments have found evidence of local adaptations along the latitudinal gradient of the Brazilian coast. However, little is known about how such adaptive heterogeneity could be affected by a rapidly changing climate in the coming decades, and the combination of deforestation and climate-induced habitat loss may affect these forests and their genetic diversity. Here, we applied two genomic-environmental association methods to model the turnover of potentially adaptive alleles for two dominant mangrove trees: Avicennia germinans and A. schaueriana. We analyzed a total of 134 individuals from six populations of A. germinans and 10 populations of A. schaueriana spanning the Brazilian coast from 1 °S to 28 °S. Gradient forest models identified temperature-related variables as the most important predictors for A. germinans outlier loci, whereas both temperature and precipitation were important for A. schaueriana. We modeled allele frequencies and projected them for future climatic scenarios to estimate adaptively driven vulnerability. We assessed climate-driven habitat loss through climate-only distribution models and calculated annual deforestation rates for each sampled region. Finally, to assess the vulnerability of individual populations, we combined the environmental suitability, deforestation data, and adaptive vulnerability projections. For both species, subtropical populations presented a higher vulnerability than equatorial populations to climate-driven habitat loss. We also identified deforestation rates at the sampled sites that were alarmingly higher than the global average mangrove deforestation rate. Our results provide improved estimates of the impacts of ongoing climate change and human-caused habitat loss on the distribution of mangroves and highlight the importance of site-based conservation strategies that consider individual subtropical and equatorial mangrove forests.

地理与环境的差异已被确认为影响巴西红树林树木遗传多样性的因素。在地理上，不同物种展现出趋同的空间遗传结构，这表明北方与南方种群之间的基因流有限。在环境方面，基因组研究和共同花园实验在巴西海岸纬度梯度上发现了局部适应性的证据。然而，关于这种适应性异质性如何受到未来几十年快速变化的气候的影响知之甚少，而森林砍伐和气候引起的栖息地丧失的结合可能影响这些森林及其遗传多样性。在此，我们应用了两种基因组-环境关联方法来模拟两种优势红树林树木——银叶树（Avicennia germinans）和施瓦红树（A. schaueriana）——潜在适应性等位基因的周转。我们分析了来自巴西海岸1 °S至28 °S的六个银叶树种群和十个施瓦红树种群的134个个体。梯度森林模型确定了与温度相关的变量是银叶树异常位点的最重要预测因子，而对于施瓦红树，温度和降水都至关重要。我们模拟了等位基因频率，并针对未来气候情景进行预测，以估计适应性驱动的脆弱性。我们通过仅考虑气候的分布模型来评估气候驱动的栖息地丧失，并计算了每个采样区域的年度森林砍伐率。最后，为了评估单个种群的风险，我们将环境适宜性、森林砍伐数据和适应性脆弱性预测相结合。对于两种物种，亚热带种群对气候驱动的栖息地丧失的脆弱性高于赤道种群。我们还确定了采样地点的森林砍伐率，该率高于全球平均的红树林森林砍伐率。我们的结果提供了对持续气候变化和人为引起的栖息地丧失对红树林分布影响的改进估计，并强调了考虑个别亚热带和赤道红树林森林的基于地点的保守策略的重要性。