Analysis and sequencing of two penguin genomes is revealing how the iconic Adelie and Emperor penguins have adapted over millions of years to life in cold and hostile Antarctica.
An international team of scientists, including Griffith University’s Professor David Lambert, has released a paper providing insight into penguin origin, fluctuations in population over the past 10 million years and potential links between biological patterns and global climate change.
Published in the open access journal GigaScience, the study is timely for the Southern Hemisphere summer in Antarctica when Adelie penguins come ashore to breed.
Having first appeared around 60 million years ago, penguins are subject to extremely low temperatures, high winds and profound changes in daylight. They inhabit an environment that most other birds could not survive.
However, thanks to a distinct evolution relative to other bird species, they have developed complex biological systems to regulate temperature and store energy for long-term fasting.
“Although Adelie and Emperor penguins both breed on the Antarctic continent, they do so in very different ways,” said Professor Lambert, Dean of Research (Griffith Sciences) and one of the co-authors of the study.
“By sequencing the genomes of two penguin species which are quite closely related, we have been able to compare many of the genes that are responsible for these different abilities to do the same thing, namely to survive and breed in Antarctica.
“We are able to reveal the genetic basis of the birds’ adaptations and their evolutionary history in response to climate change.”
For example, the study shows that the Adelie penguin population increased rapidly about 150,000 years ago when the climate became warmer, only to decline by 40 per cent about 60,000 years ago during a cold and dry glacial period.
In contrast, the Emperor penguin population remained stable, suggesting they were better adapted to glacial conditions by being able, for example, to protect their eggs from freezing temperatures and incubate them on their feet.
“This suggests that climate change may have differing impacts on both species, thus informing the approach of conservation efforts to come,” said Professor Lambert.
“These findings and other aspects of the research now provide us with the opportunity to conduct large scale evolutionary studies of both penguin species.”
Among other findings:
. Adelie and Emperor penguins have expanded genes related to beta-keratins, the proteins that make up 90 per cent of feathers. They also have at least 13 genes responsible for a single type of beta-keratin, the highest number compared to all other known bird genomes and which would explain their importance in ensuring penguin feathers are short, stiff and densely packed to minimise heat loss, remain waterproof and aid underwater flight;
. The scientists identified a gene called DSG1, known to be involved in a human dermatological disease characterised by thick skin on the palms and soles;
. The penguins were found to have exploited different adaptations for lipid (fat) metabolism in the course of their evolution, which may also provide insight into their contrasting abilities for coping with climate change.