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.

Genotypes+Weight_Table

This data file includes microsatellite data from 175 genotyped individuals. Each sample has group identity, population of origin, nest number and individual ID. This sheet contains also individual dry weight in milligrams and the knockdown time from the heat-knockdown experiment for each individual. NA values in time refer to individuals who did not fall in to heat-coma during the experiment. Status column refers to whether the individal fell in to heat-coma (1) or stayed alive (2) in the experiment.

Chill_Coma_Results

This data file contains results from the chill-coma recovery experiment with 300 individuals. Each sample has group identity, population of origin, nest number, individual ID and recovery time in minutes. NA values in time refer to individuals who did not recover from chill-coma and were considered dead in the analysis. Status column refers to whether the individal died (1) or recovered from the chill-coma(2) in the experiment.

Heat_Knockdown_Results

This data file contains results from the heat-knockdown experiment with 299 individuals. Each sample has group identity, population of origin, nest number, individual ID and knockdown time in hours. NA values in time refer to individuals who did not fall in to heat-coma during the experiment. Status column refers to whether the individal fell in to heat-coma (1) or did not fall in to heat-coma (2) in the experiment.