Evidence from a specialist parasitic insect supports range expansion and domestication of sunchoke in the Eastern Agricultural Complex

Authors: HIPPEE, ALAINE - University Of Iowa; Geib, Scott; RENQUIST, WREN - University Of Iowa; Sim, Sheina; WEINRICH, CHRISTIAN - University Of Iowa; MUELLER, NATALIE - University Of Iowa; KITCHEN, ANDREW - University Of Iowa; FORBES, ANDREW - University Of Iowa

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2025
Publication Date: 3/4/2026
Citation: Hippee, A.C., Geib, S.M., Renquist, W., Sim, S.B., Weinrich, C.L., Mueller, N.G., Kitchen, A., Forbes, A.A. 2026. Evidence from a specialist parasitic insect supports range expansion and domestication of sunchoke in the Eastern Agricultural Complex. Proceedings of the National Academy of Sciences (PNAS). 293. https://doi.org/10.1098/rspb.2025.3044.
DOI: https://doi.org/10.1098/rspb.2025.3044

Interpretive Summary: While the domestication of some plants is supported by clear physical evidence, other plants are all but invisible in the archaeological record. This research addresses whether sunchoke was domesticated as part of the Eastern Agricultural Complex (EAC; ca. 4000 YBP). We resolve historical demographic signals in the genome of a specialist parasitic fly (as a proxy for its sunchoke host) consistent with an ancestral center of diversity in the Ohio River Basin, as well as a range expansion and population size increases coincident with the timing of the EAC. This research provides a general proof of principle for using parasitic insects to study the unknown demographic histories of their plant hosts, but also specifically identifies sunchoke as an EAC domesticate.

Technical Abstract: A suite of plants, the Eastern Agricultural Complex (EAC), was domesticated in North America beginning around 4000 YBP (1-2). The sunflower Helianthus tuberosus L. (sunchoke) was also in wide cultivation at the time of European colonization (3), but it is unknown whether these were domesticated plants that had been moved around the continent, or separate cases of husbandry of local wild plants (i.e., cultivation without domestication). Evidence of a sunchoke range expansion from a smaller ancestral range, coincident with the timing of the EAC, would support a hypothesis of sunchoke domestication. For plants like H. tuberosus with large, complex, and relatively unanalyzed genomes, it is difficult and expensive to gain historical demographic insights using population genetics. Instead, we use a specialist insect parasite of H. tuberosus, Strauzia longitudinalis (Loew), to test a hypothesis of range expansion for H. tuberosus. Because the life cycle of S. longitudinalis is obligately tied to H. tuberosus, demographic and biogeographic histories of this fly should approximate those of its host plant. Employing a reduced-representation sequencing (3RAD) approach, we find that S. longitudinalis genetic diversity is highest at sites in present-day Ohio and Indiana, indicating this area as a pre-cultivation range for sunchoke. Further, demographic models suggest that S. longitudinalis from western sites split from east-central flies ~6850-2700 YBP, overlapping the timing of the EAC. Population sizes also increased during this time, consistent with a range expansion. These findings support the hypothesis that sunchoke was domesticated and should thus be considered part of the EAC.