File with environmental variables (introductions and flyways). a

envdist is a text file in Canoco format coding for the inclusion of each locality in the Pacific flyway (first column), Central flyway (second column), Atlantic flyway (third column) and the native or introduced status of each population (fourth column). The localities were assigned to flyways according to Boere and Stroud (2006). Localities are coded according to Table 1 of the paper.数据集envdist为采用Canoco格式的文本文件，用于编码各采样位点在太平洋迁徙通道（第一列）、中部迁徙通道（第二列）、大西洋迁徙通道（第三列）的归属情况，以及各种群的本土或外来状态（第四列）。采样位点的迁徙通道归属依据Boere与Stroud（2006）的研究划定，其编码规则遵循该论文的表1。