Data from: Testing the role of climate in speciation: new methods and applications to squamate reptiles (lizards and snakes)

Climate may play important roles in speciation, such as causing the range fragmentation that underlies allopatric speciation (through niche conservatism) or driving divergence of parapatric populations along climatic gradients (through niche divergence). Here, we developed new methods to test the frequency of climate niche conservatism and divergence in speciation, and applied it to species pairs of squamate reptiles (lizards and snakes). We used a large-scale phylogeny to identify 242 sister-species pairs for analysis. From these, we selected all terrestrial allopatric pairs with sufficient occurrence records (n=49 pairs) and inferred whether each originated via climatic niche conservatism or climatic niche divergence. Among the 242 pairs, allopatric pairs were most common (41.3%), rather than parapatric (19.4%), partially sympatric (17.7%), or fully sympatric species pairs (21.5%). Among the 49 selected allopatric pairs, most appeared to have originated via climatic niche divergence (61–76%, depending on the details of the methods). Surprisingly, we found greater climatic niche divergence between allopatric sister species than between parapatric pairs, even after correcting for geographic distance. We also found that niche divergence did not increase with time, further implicating niche divergence in driving lineage splitting. Overall, our results suggest that climatic niche divergence may often play an important role in allopatric speciation, and the methodology developed here can be used to address the generality of these findings in other organisms.

气候或在物种形成过程中发挥关键作用：例如，通过生态位保守性（niche conservatism）引发分布区碎片化，进而驱动异域物种形成（allopatric speciation）；或是沿气候梯度推动邻域种群发生分化，即生态位分化（niche divergence）。本研究开发了全新方法，用以检验物种形成过程中气候生态位保守性与分化的发生频率，并将其应用于有鳞目爬行动物（squamate reptiles，蜥蜴与蛇）的姐妹物种对（sister-species pairs）分析。我们借助大规模系统发育树（phylogeny）筛选出242组姐妹物种对开展分析，从中遴选具备充足物种出现记录（occurrence records）的陆地异域物种对，共计49组，并推断每一组物种的形成是否源于气候生态位保守性或是气候生态位分化。在全部242组物种对中，异域物种对最为常见（占比41.3%），其次为完全同域物种对（21.5%）、部分同域物种对（17.7%）与邻域物种对（19.4%）。在筛选出的49组异域物种对中，多数（依据方法细节不同，占比61%至76%）被推断为通过气候生态位分化形成。令人意外的是，即便校正地理距离的影响后，异域姐妹物种对间的气候生态位分化程度仍高于邻域物种对。此外，我们未发现生态位分化随时间推移而增强的现象，这进一步表明生态位分化在驱动谱系分化中具有重要作用。总体而言，本研究结果表明，气候生态位分化或常在异域物种形成过程中发挥关键作用；本研究开发的方法亦可用于验证上述结论在其他生物类群中的普适性。