https://www.pnas.org/doi/abs/10.1073/pnas.2402304121

Genetic differentiation and precolonial Indigenous cultivation of hazelnut (Corylus cornuta, Betulaceae) in western North America

Significance By analyzing genetic and morphological differentiation of hazelnut populations in the Pacific Northwest of North America, we uncover genetic patterns suggestive of cultivation practices, including long-distance transplanting and selective management. These findings challenge settler colonial views about past Indigenous land-use practices and emphasize the role of people in shaping the distribution of so-called wild plant species in precolonial North America. Ethnographic and ethnobotanical indices enhance the explanatory power of plant genetic profiles and biogeography and help to uncover the history of culturally important taxa.

Abstract Cultivation studies evaluating land-use histories and coevolutionary dynamics between humans and plants focus predominantly on domesticated species. Traditional anthropological divisions of “foragers” and “farmers” have shaped our understanding of ancient cultivation practices but have several limitations, including how people stewarded and managed nondomesticated species. To investigate the long-term effects of plant management in the Pacific Northwest, this study focuses on beaked hazelnut (Corylus cornuta) which has a long, precolonial history of management, transportation, and cultivation in British Columbia (BC, Canada). In particular, isolated hazelnut populations in northwestern BC are thought to be the result of historical transplanting and management. We sampled individual hazelnuts (n = 219) representing three distinct regions in and assessed 9,650 genome-wide SNPs identified with nextRAD genotyping-by-sequencing libraries to test for population genetic structure. We used linear measurements of individuals to assess morphological phenotypes and to identify variation between individuals and lineages. These data reveal shared genetic clusters in distant and disjunct northwestern and interior regions consistent with the movement of humans across the landscape. We also find several small genetically distinct populations in the northwestern region. The Genetic structure of hazelnut in the previously labeled “disjunct” region in Gitxsan, Ts’msyen, and Nisga’a homelands is consistent with the enduring influence of people on the distribution of purportedly “wild” plant species. Our results support the hypothesis that hazelnut was likely transplanted long distances and also managed in situ. This study highlights the often-overlooked agency of Indigenous Peoples in shaping species range distributions in North America.