Proliferation of East Antarctic Adelie penguins in response to historical deglaciation

• Published in: BMC Evolutionary Biology
• Main Authors: Younger, J, Emmerson, L, Southwell, C, Lelliott, P, Miller, K
• Format: Article in Journal/Newspaper
• Language: English
• Published: Biomed Central Ltd 2015
• Subjects: Biological Sciences; Evolutionary Biology; Biogeography and Phylogeography; Antarctic; Antarctic Peninsula; East Antarctica; Southern Ocean; The Antarctic; Antarc*; Antarctica; Pygoscelis adeliae; Sea ice
• Online Access: https://doi.org/10.1186/s12862-015-0502-2; http://www.ncbi.nlm.nih.gov/pubmed/26577544; http://ecite.utas.edu.au/105761

Background Major, long-term environmental changes are projected in the Southern Ocean and these are likely to have impacts for marine predators such as the Adlie penguin ( Pygoscelis adeliae ). Decadal monitoring studies have provided insight into the short-term environmental sensitivities of Adlie penguin populations, particularly to sea ice changes. However, given the long-term nature of projected climate change, it is also prudent to consider the responses of populations to environmental change over longer time scales. We investigated the population trajectory of Adlie penguins during the last glacial-interglacial transition to determine how the species was affected by climate warming over millennia. We focussed our study on East Antarctica, which is home to 30 % of the global population of Adlie penguins. Methods Using mitochondrial DNA from extant colonies, we reconstructed the population trend of Adlie penguins in East Antarctica over the past 22,000 years using an extended Bayesian skyline plot method. To determine the relationship of East Antarctic Adlie penguins with populations elsewhere in Antarctica we constructed a phylogeny using mitochondrial DNA sequences. Results We found that the Adlie penguin population expanded 135-fold from approximately 14,000 years ago. The population growth was coincident with deglaciation in East Antarctica and, therefore, an increase in ice-free ground suitable for Adlie penguin nesting. Our phylogenetic analysis indicated that East Antarctic Adlie penguins share a common ancestor with Adlie penguins from the Antarctic Peninsula and Scotia Arc, with an estimated age of 29,000 years ago, in the midst of the last glacial period. This finding suggests that extant colonies in East Antarctica, the Scotia Arc and the Antarctic Peninsula were founded from a single glacial refuge. Conclusions While changes in sea ice conditions are a critical driver of Adlie penguin population success over decadal and yearly timescales, deglaciation appears to have been the key driver of population change over millennia. This suggests that environmental drivers of population trends over thousands of years may differ to drivers over years or decades, highlighting the need to consider millennial-scale trends alongside contemporary data for the forecasting of species abundance and distribution changes under future climate change scenarios.