Data from: Climate-mediated hybrid zone movement revealed with genomics, museum collection and simulation modeling

Climate-mediated changes in hybridization will dramatically alter the genetic diversity, adaptive capacity and evolutionary trajectory of interbreeding species. Our ability to predict the consequences of such changes will be key to future conservation and management decisions. Here we tested through simulations how recent warming (over a 32-year period) is affecting the geographic extent of a climate-mediated developmental threshold implicated in maintaining a butterfly hybrid zone (Papilio glaucus and Papilio canadensis; Lepidoptera: Papilionidae). These simulations predict a 68 km shift of this hybrid zone. To empirically test this prediction, we assessed genetic and phenotypic changes using contemporary and museum collections and document a 40 km northward shift of this hybrid zone. Interactions between the two species appear relatively unchanged during hybrid zone movement. We found no change in the frequency of hybridization and regions of the genome that experience little to no introgression moved largely in concert with the shifting hybrid zone. Model predictions based on climate scenarios predict this hybrid zone will continue to move northward, but with substantial spatial heterogeneity in the velocity (55-144 km/1°C), shape, and contiguity of movement. Our findings suggest that the presence of non-climatic barriers (e.g., genetic incompatibilities) and/or non-linear responses to climatic gradients may preserve species boundaries as the species shift. Further, we show that variation in the “geography” of hybrid zone movement could result in evolutionary responses that differ for geographically distinct populations spanning hybrid zones and thus have implications for the conservation and management of genetic diversity.

气候介导的杂交变化将显著改变杂交类群的遗传多样性、适应能力与演化轨迹。我们对这类变化后果的预测能力，将是未来物种保护与管理决策的核心依据。本研究通过模拟实验，探究了近32年的气候变暖如何影响维持蝴蝶杂交带（hybrid zone）的气候介导发育阈值的地理范围，该杂交带涉及美洲黑凤蝶（Papilio glaucus）与加拿大凤蝶（Papilio canadensis；鳞翅目：凤蝶科）。模拟结果预测该杂交带将发生68千米的位移。为实证验证这一预测，我们利用当代采集标本与馆藏标本评估了遗传与表型变化，结果显示该杂交带已向北推移40千米。在杂交带位移过程中，两个物种间的相互作用相对未发生明显改变。我们未发现杂交频率发生变化，且几乎无基因渐渗（introgression）的基因组区域也随杂交带位移同步移动。基于气候情景的模型预测显示，该杂交带将持续北移，但位移速率（55-144千米/每摄氏度）、形态与连续性存在显著的空间异质性。本研究结果表明，在物种位移过程中，非气候障碍（如遗传不相容性（genetic incompatibilities））和/或对气候梯度的非线性响应，可能会维持物种边界。此外，我们发现杂交带位移的‘地理格局’差异，可能导致跨越杂交带的不同地理种群产生差异化的演化响应，这对遗传多样性的保护与管理具有重要启示。