Pearson correlation tests for environmental variables, Student t-test for range shift and comparisons for habitat loss in 2070

Habitat loss and shifts associated with climate change threaten global biodiversity, with impacts likely to be most pronounced at high latitudes. With the disappearance of the tundra breeding habitats, migratory shorebirds that breed at these high latitudes are likely to be even more vulnerable to climate change than those in temperate regions. We examined this idea using new distributional information on two subspecies of Black-tailed Godwits Limosa limosa in Asia: the northerly, bog-breeding L. l. bohaii and the more southerly, steppe-breeding L. l. melanuroides. Based on breeding locations of tagged and molecularly assayed birds, we modelled the current breeding distributions of the two subspecies with species distribution models, tested those models for robustness, and then used them to predict climatically suitable breeding ranges in 2070 according to bioclimatic variables and different climate change scenarios. Our models were robust and showed that climate change is expected to push bohaii into the northern rim of the Eurasian continent. Melanuroides is also expected to shift northward, stopping in the Yablonovyy and Stanovoy Ranges, and breeding elevation is expected to increase. Climatically suitable breeding habitat ranges would shrink to 16% and 11% of the currently estimated ranges of bohaii and melanuroides, respectively. Overall, this study provides the first predictions for the future distributions of two little-known Black-tailed Godwit subspecies and highlights the importance of factoring in shifts in bird distribution when designing climate-proof conservation strategies. Methods 1. Pearson correlation tests for environmental variables All variables for species distribution modelling were loaded to Qgis 3.8. We extracted the values of each variable from 101 occurrence locations (60 bohaii and 41 melanuroides) using the "raster values to points" function in Qgis 3.8. The outcome was saved as a .csv file. Next, the Pearson correlation coefficient was calculated using "tidyverse" package in R. 2. Student t-test for range shift see methods of the paper 3. Comparisons for habitat loss in 2070 see methods of the paper气候变化引发的栖息地丧失与分布偏移正威胁全球生物多样性，其影响在高纬度地区预计最为显著。随着苔原繁殖栖息地的消失，在这些高纬度区域繁殖的迁徙滨鸟，相比温带地区的同类，更易受到气候变化的冲击。本研究依托亚洲地区两种黑尾塍鹬（Limosa limosa）亚种的全新分布数据展开相关探讨：分别为北部沼泽繁殖亚种L. l. bohaii与南部草原繁殖亚种L. l. melanuroides。研究基于带标记且经分子鉴定的鸟类繁殖位点，利用物种分布模型（species distribution models）构建了两个亚种的当前繁殖分布区，并对模型的稳健性进行了检验；随后结合生物气候变量与不同气候变化情景，预测了2070年的气候适宜繁殖范围。结果显示模型稳健性良好，气候变化预计将使L. l. bohaii的分布退缩至欧亚大陆北部边缘；L. l. melanuroides同样将向北迁移，最终停滞于雅布洛诺夫山脉与斯塔诺沃伊山脉一带，且其繁殖海拔预计有所升高。气候适宜的繁殖栖息地范围将分别缩减至当前估算范围的16%与11%。总体而言，本研究首次针对两种鲜为人知的黑尾塍鹬亚种的未来分布作出预测，并强调在制定气候适应性保护策略时，纳入鸟类分布偏移因素的重要性。 研究方法 1. 环境变量的皮尔逊相关性检验 将所有用于物种分布建模的变量导入QGIS 3.8，借助QGIS 3.8中的"栅格值转点"工具，从101个出现位点（其中60个为L. l. bohaii样本，41个为L. l. melanuroides样本）中提取各变量的数值，将结果保存为.csv格式文件。随后使用R语言的"tidyverse"包计算皮尔逊相关系数。 2. 分布偏移的学生t检验 详见论文原文方法部分。 3. 2070年栖息地丧失情况对比 详见论文原文方法部分。