Thirty years of ancient DNA and the faunal biogeography of Aotearoa New Zealand: lessons and future directions

Thirty years ago, DNA sequences were obtained from an extinct Aotearoa New Zealand animal for the first time. Since then, ancient DNA research has provided many - often unexpected - insights into the origins of New Zealand's terrestrial and marine vertebrate fauna. Because recent human activities in New Zealand have caused the decline or extinction of many endemic plant, bird, reptile, and marine mammal species, ancient DNA has been instrumental in reconstructing their identities and origins. However, most ancient DNA studies focusing on New Zealand species have been restricted to vertebrates, with small sample sizes, and/or relatively few genetic markers. This has limited their power to infer fine-scale biogeographic patterns, including (pre)historic distributions and range-shifts driven by past climate and environmental change. Recently, 'next-generation' methodological and technological advances have broadened the range of hypotheses that can feasibly be tested with ancient DNA. These advances represent an exciting opportunity for further exploring New Zealand biogeography using ancient DNA, but their promise has not yet been fully realised. In this review, we summarise the last 30 years of ancient DNA research into New Zealand faunal biogeography and highlight key objectives, challenges, and possibilities for the next 30 years and beyond.