Environment dependence of the expression of mutational load and species' range limits. (15th March 2022)

• Record Type: Journal Article
• Authors: Perrier, Antoine; Sánchez‐Castro, Darío; Willi, Yvonne
• Is Part Of: Journal of evolutionary biology. Volume 35:Number 5(2022)
• Page Start: 731
• Page End: 741
• Publication Date: 2022-03-15
• Subjects: Arabidopsis lyrata -- environmental stress -- genetic drift -- heterosis -- mutational load -- range limit -- temperature gradient; Evolution (Biology) -- Periodicals; Biology -- Periodicals; 576.8
• DOI: 10.1111/jeb.13997
• Languages: English
• ISSNs: 1010-061X

Abstract

Abstract: Theoretical and empirical research on the causes of species' range limits suggest the contribution of several intrinsic and extrinsic factors, with potentially complex interactions among them. An intrinsic factor proposed by recent theory is mutational load increasing towards range edges because of genetic drift. Furthermore, environmental quality may decline towards range edges and enhance the expression of load. Here, we tested whether the expression of mutational load associated with range limits in the North American plant Arabidopsis lyrata was enhanced under stressful environmental conditions by comparing the performance of within‐ versus between‐population crosses at common garden sites across the species' distribution and beyond. Heterosis, reflecting the expression of load, increased with heightened estimates of genomic load and with environmental stress caused by warming, but the interaction was not significant. We conclude that range‐edge populations suffer from a twofold genetic Allee effect caused by increased mutational load and stress‐dependent load linked to general heterozygote deficiency, but there is no synergistic effect between them. Abstract : Recent theory suggests species' range limits may be caused by edge populations suffering from mutation accumulation as a result of increased genetic drift. Here we tested whether the expression of mutational load of range‐edge populations was dependent on environmental stress typical for peripheral environments. We found that the expression of mutational load was not enhanced under stress in Arabidopsis lyrata, but that this species suffers from a general stress‐dependent heterozygote deficit. Our results suggest that range‐edge populations may suffer from two independent genetic Allee effects, heightened mutational load and stress‐dependent load linked to heterozygote deficiency.