A new paper published in PNAS presents a genomics-informed framework for evaluating when genetic rescue - moving individuals between populations to increase genetic diversity and reduce inbreeding - is likely to succeed. Despite growing interest in genetic rescue, concerns about outbreeding depression, where admixed individuals exhibit reduced fitness, often limit its application.

Using whole-genome data from populations of the endangered marsh fritillary butterfly in Denmark, the study combines information on inbreeding, demographic history, past gene flow, and local adaptation to assess risks associated with mixing populations. The results reveal high inbreeding, recent divergence, and no apparent local adaptation, suggesting a low risk of outbreeding depression and a high potential for successful genetic rescue.

The study demonstrates that even moderate genomic resources can provide actionable guidance for conservation management. By translating genomic analyses into a clear and broadly applicable decision-making framework, the work helps bridge the gap between evolutionary genomics and practical conservation action.