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Full-Text Articles in Life Sciences

A Threat To New Zealand's Tuatara Heats Up, Kristine L. Grayson, Nicola J. Mitchell, Nicola J. Nelson Sep 2014

A Threat To New Zealand's Tuatara Heats Up, Kristine L. Grayson, Nicola J. Mitchell, Nicola J. Nelson

Biology Faculty Publications

No matter how many times we head to one of New Zealand's offshore islands, the feelings are always a mix of sheer awe at the beauty and biodiversity preserved in these special refuges and lingering nerves. Did we remember all the gear? Do we have enough food and water in case we get stuck? Can the helicopter land on the side of a cliff in these winds? These epic journeys are in pursuit of a lone remnant of the reptile evolutionary tree, with a unique ecology that has big implications under climate change.


Sex Ratio Bias And Extinction Risk In An Isolated Population Of Tuatara (Sphenodon Punctatus), Kristine L. Grayson, Nicola J. Mitchell, Joanne M. Monks, Susan N. Keall, Joanna N. Wilson, Nicola J. Nelson Apr 2014

Sex Ratio Bias And Extinction Risk In An Isolated Population Of Tuatara (Sphenodon Punctatus), Kristine L. Grayson, Nicola J. Mitchell, Joanne M. Monks, Susan N. Keall, Joanna N. Wilson, Nicola J. Nelson

Biology Faculty Publications

Understanding the mechanisms underlying population declines is critical for preventing the extinction of endangered populations. Positive feedbacks can hasten the process of collapse and create an ‘extinction vortex,’ particularly in small, isolated populations. We provide a case study of a male-biased sex ratio creating the conditions for extinction in a natural population of tuatara (Sphenodon punctatus) on North Brother Island in the Cook Strait of New Zealand. We combine data from long term mark-recapture surveys, updated model estimates of hatchling sex ratio, and population viability modeling to measure the impacts of sex ratio skew. Results from the mark-recapture surveys show ...