Digest: Local adaptation of dormancy onset cues in a species expanding its range.

In temperate climates, dormancy enables organisms to survive winter, with timing often tied to environmental cues, such as daylength, that differ along latitudinal gradients. Adaptation to these gradients is crucial during range expansion. Clark et al. (2026) found that in the introduced northern tamarisk beetle (Diorhabda carinulata), populations from the range core were locally adapted in dormancy timing to core environments, while newly arrived edge populations showed heterogeneous responses to daylength, consistent with adaptation to seasonal timing. Genetic variation and high heritability in dormancy traits in the core populations likely drive range expansion potential through rapid evolution of dormancy traits.