Data from: Thermal tolerance in two wood ant species and their hybrids

Local populations can cope with rising temperatures, if they have adaptive potential to face the new thermal regime. Hybridization with a closely related lineage is one potential source of adaptive genetic variability and an outstanding question is whether hybridization could help contemporary populations to adapt in the face of current environmental change. We investigate thermal adaptation by testing for differences in cold and heat tolerances between Finnish populations of two mound-building wood ants, Formica polyctena and Formica aquilonia, and their naturally occurring hybrids. The results showed that parental individuals differed in both cold and heat tolerances and expressed thermal limits which reflect the global distributions of the parental species, in support to the thermal adaptation hypothesis. However, hybrids could not combine the thermal tolerance of both parental species as they were equally heat-tolerant to F. polyctena, but not equally cold-tolerant to F. aquilonia. Intriguingly, body weight had a significant role in thermal tolerance, with heavier ants coping better with higher temperatures. These results contribute to understanding the outcomes of hybridization and the potential that species possess in coping with environmental change. Wood ants are keystone species in the boreal forests and important for healthy forest ecosystems, but they are threatened by increasing global temperatures and habitat destruction. Our findings help to understand how these species may respond to global climate change.

本地种群若具备适应新型热环境的潜力，即可应对气温升高的挑战。与近缘类群的杂交是产生适应性遗传变异（adaptive genetic variability）的潜在途径之一，而一个悬而未决的核心问题是：杂交是否能够助力当前种群应对当下的环境变化？
本研究以芬兰境内的两种筑丘木蚁——多栉蚁（Formica polyctena）与红褐林蚁（Formica aquilonia）及其天然杂交种群为研究对象，通过比较三者的耐寒性与耐热性差异，探究其热适应机制。研究结果显示，两种木蚁的亲本个体在耐寒性与耐热性上均存在显著差异，其热极限温度恰好契合各自亲本物种的全球分布格局，这一结果支持了热适应假说（thermal adaptation hypothesis）。然而，杂交种群无法兼具两种亲本的热耐受能力：其耐热性与多栉蚁相当，但其耐寒性却并未达到红褐林蚁的水平。值得注意的是，体重对热耐受能力存在显著影响：体重更大的个体能够更好地应对高温环境。
本研究结果有助于阐明杂交的演化结果，以及物种应对环境变化的潜在能力。筑丘木蚁是北方针叶林的关键物种（keystone species），对维持森林生态系统的健康至关重要，但它们正面临全球气温升高与栖息地破坏的威胁。本研究的发现有助于我们理解这些物种将如何响应全球气候变化。