Speciation: A second chance to become two.

Long-separated European butterfly lineages can both merge and remain distinct, with evidence of ancient interbreeding and current reproductive barriers.

• Why it matters: Understanding how species maintain separation despite historical gene flow is crucial for grasping speciation processes and biodiversity conservation.
• What they did: Researchers examined a protected European butterfly, analyzing genetic data and male chemical signals across two lineages that previously interbred but now stay separate.
• The result: Findings reveal that these lineages experienced ancient interbreeding yet are now kept apart by divergent male signals, illustrating a dynamic balance between merging and maintaining species boundaries.