Araucaria bidwillii genomics suggest Indigenous Peoples broadened translocation practices in response to settler colonialism

1. Retracing past anthropogenic dispersal of culturally important taxa offers insights to the biogeographic history of species, as well as the history of the people who interacted with them. Bunya Pine (Araucaria bidwillii Hook.) is a culturally and spiritually significant conifer tree for several Indigenous groups in eastern Australia. Sharing the edible nuts and attending Bunya gatherings is an important way for these groups to maintain their cultural connections and it has been hypothesized that prior to European colonization, Indigenous Peoples facilitated the dispersal of Bunya Pine as part of these ancient traditions. 2. We used ethnohistorical information on the use of Bunya Pine by Indigenous Peoples to interpret genomic patterns within and between disjunct distributions of Bunya Pine. 3. We found signatures of long-term isolation within the Australian Wet Tropics (AWT) and extensive gene flow within southeast Queensland (SEQ) that does not fit models of faunal or passive dispersal. Within SEQ, we found greater population structure amongst sites known to pre-date European colonization, than when colonial-era planted sites were included in our analyses, suggesting that pre-colonial translocation was sporadic or localized rather than systematic and widespread. Increased Indigenous translocations in conjunction with plantings by European settlers appears to have erased the natural pre-colonial population structure of SEQ Bunya Pine. Our stairway plot models suggest sharp population decline of SEQ Bunya Pine in the early and late Pleistocene, though we did not find evidence that anthropogenic dispersal facilitated effective population size growth of the species in the Holocene. 4. We concluded that pre-colonial translocation of SEQ Bunya Pine was likely restricted by kinship-based custodial rights, and that when Indigenous Peoples were displaced by European settlers, translocation was intensified to maintain cultural connectivity. This study is an example of how Indigenous Australian groups adapt plant management strategies to meet socio-cultural needs and demonstrates the potential for plant genomics to supplement Indigenous Biocultural Knowledge that has been impacted by colonial dispossession.