Project

4184

Chief Investigator

BURRIDGE, Dr Christopher (Chris) - University of Tasmania

Title

Conservation genetics of Antarctic seabirds and seals: population connectivity and past glacial refugia


Project aims

The aim of this study is to understand how iconic Antarctic species such as penguins and seals have responded to past climate changes. We will use molecular tools to seek genetic signatures of past breeding refuges and understand how today's populations arose from those refugia. We will also use genetic data to understand migration and genetic diversity in present-day populations. From this knowledge we can predict the fate of those species under future climate change scenarios, their ability to adapt to new environmental conditions, and can assess the risk of local or widespread extinction.

Project gallery


Project Summary of the Season 2012/13

During the 2012/13 Antarctic Field season we were able to collect tissue samples from a range of Antarctic seabirds that will be used for future genetic analysis to understand past and present population processes. Samples included moult feathers, carcasses and wings found in and around nesting sites that could be collected without disturbing animals. The species sampled included Adelie penguins, Storm petrels, Skuas and Snow petrels. Tissue (muscle) samples from Emperor penguins were collected from chicks that had died of natural causes and were found well away from live penguins. Bones were also collected from Emperor penguins near a lake in the Vestfold Hills. These birds had died a long time ago and will be important in understanding the rate of change in penguin DNA through time.

Project Summary of the Season 2013/14

Our research is focussed on using genetic techniques to understand how Antarctic seals and seabirds are likely to have responded to environmental changes since the end of the Last Glacial Maximum (LGM) about 20,000 years ago. During the LGM, the sea ice surrounding Antarctica extended nearly two times farther north than at present and temperatures were about 13? C colder than today. We investigated what effect the retreat of this extensive sea ice had on the size of the population of various species, as well as the distribution of their breeding colonies. Our latest results indicate that historically Weddell seals populations remained stable, whereas Emperor penguins decreased in abundance by a factor of six during the last glacial period. Emperor penguins appeared to have survived near two large polynyas (areas of open water in the sea ice) where they could forage. Individual breeding colonies were probably more distant from each other than they are today.

Project Summary of the Season 2014/15

Through our work over the last year, we have discovered that penguins and Weddell seals possess differing abilities to adapt to environmental change, despite their remarkably similar habitat requirements and overlapping distributions. The results of our molecular investigations show that emperor penguin and Adélie penguin numbers increased dramatically over the past 10,000 years, while Weddell seal numbers remained constant. Emperor penguins appear to have been restricted into three refuge populations during the last ice age, whereas Adélie penguins only had two populations. These ice age refugia may have been located near polynyas (areas of open water in the sea ice) which allowed penguins access to the water to forage. One of these refugia for both emperor and Adélie penguins was probably located in the Ross Sea, which is still an important breeding habitat for penguins today.
We have also discovered that penguins spanning 8000 kilometres of coastline are interbreeding, suggesting they migrate much further around Antarctica than previously thought. This finding has important implications for forecasting studies that have so far considered breeding colonies as isolated units.

Final Summary of Project Achievements

We used molecular methods to study past changes in the distribution and population size of emperor and Adelie penguins, Snow petrels and Weddell Seals across East Antarctica, and found that despite their similar habitat requirements and overlapping distributions, each has experienced very different past population trajectories, and hence are likely to have differing abilities to adapt to future environmental change.

During the Last Glacial Maximum (LGM), the sea ice surrounding Antarctica extended nearly two times farther north than at present and temperatures were about 13 degrees colder than today. Our results showed that the two penguin species had reduced populations during the last ice age, probably surviving as remnant populations in refugia associated with polynyas (areas of open water in the sea ice) where they could feed. However their populations have increased dramatically in size over the past 10,000 years following the Last Glacial Maximum (LGM).

In contrast to penguins, Snow petrels and Weddell seals seem to have been more robust, having endured the LGM with large population sizes which continue to the present day. Their success through the last ice age may be related to either their capacity to tolerate changes in climate or, in the case of the Snow petrels, the ability to fly and access a range of food sources.

Our results show that traits characteristic to each species can influence their response to the same environmental events, despite broad ecological similarities among species. Such knowledge is important as we develop strategies to conserve Antarctic seabird and seal populations under current environmental change.

Category 1: Peer-reviewed literature

Younger J.L., Clucas G.V., Kooyman G., Wienecke B., Rogers A.D., Trathan P.N., Hart T., Miller K.J. (2015) Too much of a good thing; sea ice extent may have forced Emperor penguins into refugia during the last glacial maximum, Global Change Biology 21(6). 2215–2226; [Ref: 15692]

Younger J.L., Emmerson L.M., Miller K.J. (2015) The influence of historical climate changes on Southern Ocean marine predator populations: a comparative analysis, Global Change Biology .; [Ref: 15693]

Younger J., Emmerson L., Southwell C., Lelliott P., Miller K. (2015) Proliferation of East Antarctic Adélie penguins in response to historical deglaciation, BMC Evolutionary Biology 15:236. .; [Ref: 15760]

Younger J.L., van den Hoff J., Wienecke B., Hindell M., Miller K.J. (2016) Contrasting responses to a climate regime change by sympatric, ice-dependent predators, BMC Evolutionary Biology 16:61. .; [Ref: 15761]

Clucas G.V., Younger J.L., Kao D.M., Rogers A.D., Handley J., Miller G.D., Jouventin P., Nolan P., Gharbi K., Miller K.J., Hart T. (2016) Dispersal in the sub-Antarctic: king penguins show remarkably little population genetic differentiation across their range, BMC Evolutionary Biology 16. 211; [Ref: 15832]