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Suturing fragmented landscapes: Mosaic hybrid zones in plants may facilitate landscape restoration

Massatti, Rob1; Faske, Trevor1; Barnes, Ivana2; Leger, Elizabeth3; Parchman, Thomas3; Richardson, Bryce4; Knowles, L. Lacey2

Published Feb 08, 2025 on Dryad. https://doi.org/10.5061/dryad.1g1jwsv6r

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Feb 08, 2025 version files 121.79 MB

Abstract

Many widespread plant taxa of western North America have diversified into phenotypically and genetically divergent lineages due to complex biogeographic histories across heterogeneous landscapes. Mosaic hybrid zones can form when geographically co-occurring yet environmentally distinct lineages cross-pollinate and form hybrids that occupy unique environmental niches absent of a geographic cline. This expands the total environmental space across which parental and hybrid individuals grow, resulting in larger, less fragmented geographic distributions. Here, we highlight hybridization mosaics across three study systems containing taxa critical to widespread plant communities in western North America: Ericameria nauseosa, Artemisia tridentata, and Sphaeralcea fendleri. The systems contain diverged taxa that co-occur geographically across the landscape, though not environmentally, and hybridize readily. Hybridization among taxa has facilitated niche expansion into intermediate environments consistent with unique combinations of adaptive genetic variation, creating more continuity within each study system (study systems occupy ~820–270,000 km2 more geographic space by virtue of hybridization). Furthermore, hybrids are predicted to play important roles in future climates (they occupy 8–475% more geographic area compared to present in a high emission climate scenario). This convergent pattern signals mosaic hybridization as an underappreciated mechanism with broad ecological and evolutionary ramifications and suggests understanding the consequences of this process may be critical to predict responses of taxa to changing climates. Moreover, leveraging mosaic hybridization may assist the creation of restoration management plans that aim to mitigate the deleterious effects of habitat fragmentation on ecosystems in the context of climate change.