Human-facilitated dispersal of pawpaw (Asimina triloba [L.] Dunal) at its northern range limits: re-examining the historical and archaeological evidence

Fundamental to understanding plant species distributions are the roles of natural and anthropogenic mechanisms of dispersal. Recent attention has focused on mechanisms of long-distance dispersal, and some research has examined whether past Indigenous peoples dispersed preferred plant species long distances in North America. Assessing dispersal mechanisms is crucial to understanding a plant’s capacity for range shifts under future climate change. This study investigated the northern distribution of pawpaw (Asimina triloba [L.] Dunal), a species of ecological, horticultural, and cultural value for which researchers have debated the relative role of different dispersal mechanisms including past Indigenous facilitation. Focusing on western New York State (NYS), this study employed interdisciplinary analysis to infer the possibility of human-facilitated dispersal of the species, including by analysing archaeological site data and historical records. Results suggested that pawpaw distribution is primarily driven by natural dispersal (i.e. hydrochory, endozoochory), though some populations may have originated from Indigenous or Euro-American planting. Given the buoyant characteristics of A. triloba fruit and seeds, Great Lakes (i.e. Lake Erie and Lake Ontario) currents were and are capable of facilitating long-distance dispersal into western NYS. This study also suggested that A. triloba is less rare in the study area than once thought (n = 70 populations historically and/or presently) and is within its climatic limits. This study broadly provided insight into the relative roles of natural and human-aided dispersal for a noteworthy tree species of eastern North America.