One of the greatest environmental impacts of ancient people was the introduction of both domestic and wild species to non-native habitats. Globalization has led to the rapid spread of exotic and invasive species, but the movement of species through trade networks and human migration extends back at least 20,000 years and intensifies during the last 10,000 years. The analysis of ancient DNA and genomic data permits one to investigate the possible prehistoric introduction or movement of the now endangered island fox (Urocyon littoralis) by Native Americans across the California Channel Islands. The Channel Islands contain some of the earliest human occupations in coastal North America at 13,000 cal BP and some of the most populous hunter-gather groups in the world with extensive trade networks between the islands and mainland.
The endemic island fox of California's Channel Islands is a federally listed endangered species and has been the subject of considerable conservation research, including a captive breeding program. Despite decades of research, significant questions remain about when foxes colonized the Channel Islands and the role that Native Americans may have played in their introduction and dispersal to six islands. Most researchers agree that Native Americans deliberately introduced island foxes from the northern to the southern Channel Islands by 5,000 years ago, and recent research raises the possibility that Native Americans may have first introduced foxes from the mainland to the northern Channel Islands. This is supported by their widespread distribution on six islands, their absence in fossil deposits or in very early archaeological contexts, and the significance of foxes in Native American religion and ceremony.
Using archaeological, historic (19-20th century), and extant island foxes samples, C. Hofman is characterizing genetic variation of thousands of loci across the island fox genome to test the hypothesis that foxes were first introduced to the Channel Islands by Native Americans during the Holocene. By dating dispersal/introduction events and placing them in the context of the archeological/fossil records using high throughput sequencing, this study will investigate the role of anthropogenic, biotic (introduction and dispersal of other species), and environmental factors (e.g. climate change) in shaping island fox genetic variation across several millennia. These data will allow a better understanding of how humans have interacted with and influenced animals by introducing them to new environments, obscuring the distinction between nature and culture.
This study will form Hofman's PhD dissertation and will be published in peer-reviewed archaeological, biological, and interdisciplinary journals, synthesized in a technical report, and summarized in a brief educational document for the Channel Islands National Park (CHIS). This project will demonstrate the importance of integrating archaeology and genomics for understanding ancient and modern human environmental relationships and modern conservation biology. Archaeological investigations of human-animal relationships through time can help document the influence of Native Americans on species distribution, abundance, and ecology. Understanding how species and humans adapted to and influenced changing environments in the past will inform decisions about protecting, preserving, and restoring biodiversity in the future.
Understanding human-animal relationships in the past and present is a fundamental area of archaeological research. Throughout human history, animals have been sources of food, raw materials (hides, bones, oil, etc.), labor, and companionship. Humans have also had an important influence on animal populations, resulting in extinction, domestication, and translocation. Archaeological research on the interactions between humans and animals has also helped us understand the contemporary status of animal populations, providing important insights for conservation biology and establishing a new research agenda for archaeology (i.e., conservation archaeobiology). The endemic island fox (Urocyon littoralis) of California’s Channel Islands is a federally listed endangered species and has been the subject of considerable conservation research, including a captive breeding program. Despite decades of research, significant questions remain about when foxes colonized the Channel Islands and the role that Native Americans may have played in introducing foxes to the Channel Islands or translocating island foxes between islands. Most researchers agree that Native Americans deliberately introduced island foxes from the northern to the southern Channel Islands by 5,000 years ago, and recent research raises the possibility that Native Americans may have first introduced foxes from the mainland to the northern Channel Islands. Using high throughput DNA sequencing, we investigated the role of anthropogenic, biotic (introduction and dispersal of other species), and environmental factors (e.g. climate change) in shaping island fox genetic variation across the last several millennia. We have successfully sampled ~500 archaeological, historic, and modern island foxes for genetic analysis through visits to several collections including Santa Barbara Museum of Natural History (SBMNH), Natural History Museum of Los Angeles (NHMLA), University of California Santa Barbara (UCSB), California State University –Northridge (CSUN), California State University –Los Angeles (CSULA), and through collaborations with the National Park Service and Nature Conservancy. Nine of the potentially oldest archaeological samples have been Aceelerator Mass Spectrometry (AMS) radiocarbon dated to establish a chronology for human interaction with foxes and to calibrate our genetic analyses. Our genetic analysis of modern samples suggests that foxes arrived on the northern Channel Islands ~ 9200-7100 years ago, well within the 13,000 years since human arrived. Humans moved foxes to the southern Channel Islands soon after they arrived on the northern islands. From their mainland gray fox progenitor, island foxes likely underwent very rapid morphological and behavioral change ~2000 years or less. Using ancient DNA, we are now developing more rigorous hypotheses about how foxes first arrived on the Channel Islands—by human translocation or natural rafting? Regardless of mechanism, foxes have been on the islands for at least 7000 years and have adapted to and weathered considerable environmental and cultural change. This study provides a new approach to integrating archaeological, paleontological, and biological datasets to examine biogeographic patterns of wild animals and plants and the evolution of endemic and endangered species. These data will also allow us to better understand how humans have manipulated and influenced animals by introducing them to new environments and inform conservation and management of small endemic populations.
