Human-mediated extirpation of the unique Chatham Islands sea lion and implications for the conservation management of remaining New Zealand sea lion populations

TitleHuman-mediated extirpation of the unique Chatham Islands sea lion and implications for the conservation management of remaining New Zealand sea lion populations
Publication TypeJournal Article
Year of Publication2016
AuthorsRawlence N.J, Collins C.J, Anderson C.NK, Maxwell J.J, Smith I.WG, Robertson B.C, Knapp M., Horsburgh K.A, Stanton J.AL, Scofield R.P, Tennyson A.JD, Matisoo-Smith E.A, Waters J.M
JournalMolecular Ecology
Volume25
Pagination3950-3961
Date Published2016/08
Type of ArticleArticle
ISBN Number0962-1083
Accession NumberWOS:000381578200012
Keywordsalignment; Ancient DNA; Chatham Islands; dispersal; evolution; extinction; fishcrics bycatch; human; impact; inference; New Zealand sea lion; penguins; Phocarctos hookeri; phocarctos-hookeri; polynesia; sequences; Tipping points
Abstract

While terrestrial megafaunal extinctions have been well characterized worldwide, our understanding of declines in marine megafauna remains limited. Here, we use ancient DNA analyses of prehistoric (<1450-1650 AD) sea lion specimens from New Zealand's isolated Chatham Islands to assess the demographic impacts of human settlement. These data suggest there was a large population of sea lions, unique to the Chatham Islands, at the time of Polynesian settlement. This distinct mitochondrial lineage became rapidly extinct within 200 years due to overhunting, paralleling the extirpation of a similarly large endemic mainland population. Whole mitogenomic analyses confirm substantial intraspecific diversity among prehistoric lineages. Demographic models suggest that even low harvest rates would likely have driven rapid extinction of these lineages. This study indicates that surviving Phocarctos populations are remnants of a once diverse and widespread sea lion assemblage, highlighting dramatic human impacts on endemic marine biodiversity. Our findings also suggest that Phocarctos bycatch in commercial fisheries may contribute to the ongoing population decline.

DOI10.1111/mec.13726
Short TitleMol. Ecol.
Student Publication: 
No
Research Topics: 
sharknado