(Post by lab graduate Carolyn Flower, M. sc.)

We just published our open access study in Global Ecology and Biogeography on how human food use can potentially influence plant geographical ranges in the Sonoran Desert. The use of plants for food is one of the most important ways in which humans can increase distributions, via propagation, wild harvesting and dispersal. Human populations have potentially reorganized plant distributions at regional and continental scales via food use, which can be seen across the world from Amazonia and Southeast Asia to eastern North America. The Sonoran Desert is also a resource-rich environment with a long history of human occupation by both foraging and agricultural populations (e.g. the Hohokam archaeological culture c. 400-1450 CE). However, we still lack an understanding of human impacts on geographical distribution of the vast majority of food plants that are no longer a major component of human diets within the Sonoran Desert.

This challenge can be addressed via studying range filling defined here as the ratio between the realized range (R) and potential (P) geographic range. R/P is a measure of how well species have dispersed to fill their potential ranges. The study asks (a) does human food use in prehistoric and historic times increase R/P, and (b) what ecological traits predisposed species to higher R/P via interactions with plant use?

Interestingly, we found that Sonoran Desert species that have been documented as being used for food filled their potential range more than unused congeners. We also found that food plant species had higher range filling among annual or non-herbaceous species, suggesting that the effect of human use on geographical ranges is likely to have been greatest for these types of species.

This has been a really fascinating and challenging journey to publication! I was originally very excited about this research question because of my interests in the connection between plants and people. My other main motivation for this project was to highlight the importance of collaboration amongst disciplines and the importance of traditional knowledge within scientific research. Our work can add to the growing consensus that people and nature must be considered together in the Anthropocene, and that traditional use of plants can have positive effects on the ecosystems broadly. The ethnobotanical dataset we developed was comprised of 349 Sonoran Desert food plants, and the only reason we know about the uses of these plants is through traditional knowledge. As such, this paper is also a call for deeper collaboration with Indigenous communities and recognition of their traditional and critical role in stewarding regional biodiversity.