title: Geographically contrasting biodiversity reductions in a widespread New Zealand seabird.
abstract: Unravelling prehistoric anthropogenic impacts on biodiversity represents a key challenge for biologists and archaeologists. New Zealand's endemic Stewart Island Shag (Leucocarbo chalconotus) comprises two distinct phylogeographic lineages, currently restricted to the country's south and southeast. However, fossil and archaeological remains suggest a far more widespread distribution at the time of Polynesian settlement ca. 1280 AD, encompassing much of coastal South Island. We used modern and ancient DNA, radiocarbon dating, and Bayesian modelling, to assess the impacts of human arrival on this taxon. Our analyses show that the southeast South Island (Otago) lineage was formerly widespread across coastal South Island, but experienced dramatic population extinctions, range retraction and lineage loss soon after human arrival. By comparison, the southernmost (Foveaux Strait) lineage has experienced a relatively stable demographic and biogeographic history since human arrival, retaining much of its mitochondrial diversity. Archaeological data suggest that these contrasting demographic histories (retraction vs. stability) reflect differential human impacts in mainland South Island vs. Foveaux Strait, highlighting the importance of testing for temporal and spatial variation in human-driven faunal declines.
authors.affiliation: Allan Wilson Centre, Department of Zoology, University of Otago, Dunedin, New Zealand.
authors.forename: Nicolas J
authors.initials: NJ
authors.lastname: Rawlence
authors.affiliation: Allan Wilson Centre, Department of Zoology, University of Otago, Dunedin, New Zealand.
authors.forename: Martyn
authors.initials: M
authors.lastname: Kennedy
authors.affiliation: Scripps Institution of Oceanography, University of California, San Diego, CA, 92093, USA.
authors.forename: Christian N K
authors.initials: CN
authors.lastname: Anderson
authors.affiliation: Department of Integrative Biology, University of California, Berkeley, CA, 94720-3140, USA.|Allan Wilson Centre, Department of Anatomy, University of Otago, Dunedin, New Zealand.
authors.forename: Stefan
authors.initials: S
authors.lastname: Prost
authors.affiliation: Allan Wilson Centre, Department of Zoology, University of Otago, Dunedin, New Zealand.|School of Human Evolution and Social Change, Arizona State University, Tempe, AZ, USA.
authors.forename: Charlotte E
authors.initials: CE
authors.lastname: Till
authors.affiliation: Department of Anthropology and Archaeology, University of Otago, Dunedin, New Zealand.
authors.forename: Ian W G
authors.initials: IW
authors.lastname: Smith
authors.affiliation: Canterbury Museum, Christchurch, New Zealand.
authors.forename: R Paul
authors.initials: RP
authors.lastname: Scofield
authors.affiliation: Museum of New Zealand Te Papa Tongarewa, Wellington, New Zealand.
authors.forename: Alan J D
authors.initials: AJ
authors.lastname: Tennyson
authors.affiliation: 42 Ann Street, Dunedin, New Zealand.
authors.forename: Jill
authors.initials: J
authors.lastname: Hamel
authors.affiliation: Department of Marine Science, University of Otago, Dunedin, New Zealand.
authors.forename: Chris
authors.initials: C
authors.lastname: Lalas
authors.affiliation: Allan Wilson Centre, Department of Anatomy, University of Otago, Dunedin, New Zealand.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Matisoo-Smith
authors.affiliation: Allan Wilson Centre, Department of Zoology, University of Otago, Dunedin, New Zealand.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Waters
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D001717:Birds / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics; D053476:Extinction, Biological; D005580:Fossils; D014644:Genetic Variation; D006801:Humans; D016013:Likelihood Functions; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009520:New Zealand; D010802:Phylogeny; D058974:Phylogeography; D011157:Population Dynamics; D055110:Radiometric Dating; D017422:Sequence Analysis, DNA; D062211:Spatio-Temporal Analysis
chemical_list: D004272:DNA, Mitochondrial
keywords: Leucocarbo chalconotus; Stewart Island Shag; ancient DNA; biodiversity; demography; extinction; human impact; megafauna; overkill; seabird