Format: ORAL

Madeline Slimp1 Lisa Martinez2 Glen Macdonald2 Don Hankins3 Matthew Kirby4 Josh Kapp1 Sebastian Melrose1 Beth Shapiro1 Rachel Meyer1

1 Department of Ecology and Evolutionary Biology, University of California Santa Cruz, California, USA 2 Department of Geography, University of California Los Angeles, California, USA 3 Geography and Planning Department, California State University Chico, California, USA 4 Department of Geological Sciences, California State University Fullerton, California, USA

Humans have steadily been in Southern California for 14,000 years. Despite this legacy of human presence, studies showing the historical composition of the organisms that cohabited this Southern California with humans are scant. Sedimentary ancient eDNA can be used as a tool to reconstruct thousands of years of plant and mammal presence records, and may present a more sensitive spatiotemporal scale than pollen records. We sequenced the mammal and plant DNA present in a sediment core from Lake Elsinore, spanning 24,000 years of natural history and 10,000 years of human settlement. Preservation of environmental DNA is poor in warm climates, so we tested the Angiosperms353 Target Capture Kits effectiveness in increasing the proportion of diagnostic plant sequences for ancient metagenomic samples. We find that the Angiosperms353 libraries have a greater proportion of reads mapped on average, and a greater plant target richness. From the target capture data, we seek to trace ethnobotanical families, like Rutaceae, Fagaceae, and Apiaceae, to characterize the landscape around the time of human arrival to understand some of the challenges and opportunities presented to early inhabitants. Further, we associate characteristic environmental changes, like shrubland dominance and absence of widespread taxonomic groups, with a newly reconstructed charcoal history, suggesting that humans have been ecosystem engineers via controlled use of fire for thousands of years. This project validates the preservation and recovery of ancient eDNA using Angiosperms353 in warm-climate sediment cores from southern California, which can be a tool that helps define the role of humans in shaping Californias ecological history.