Multiple climatic fluctuations over the past 60 million years have led to the evolution of modern penguins. A team led by Teresa L. Koll of the University of Copenhagen came to this conclusion based on a comprehensive analysis of penguin fossils and the genes of modern animals. As the working group reports in the journal Nature Communications., the group of fauna originated in the now largely submerged Microcontinental Zealand, of which only New Zealand remains above the water surface. Today’s penguins arose about 14 million years ago, when great cooling led to a small mass extinction and the formation of the East Antarctic ice sheet.
Long before the southern ice sheets formed, penguins lost their ability to fly and became excellent swimmers. As a result, they spread to South America and Antarctica. Many new species formed when the Drake Passage between South America and Antarctica opened about 30 million years ago and formed the Antarctic Current. Another evolutionary breakthrough occurred in the past three million years, when fluctuations between warm and cold periods repeatedly cut penguins into individual regions, giving rise to new species.
Genetic data indicate that it was only during this period that penguins began to eat crustaceans like krill again. Before that, they had lost almost all of the genes that allowed them to break down chitin in their shells – a clear indication that penguins ate plants or fish for a long time. The data also show that many genes that strongly evolved in penguins encode adaptations to diving and later also to cold. Animals have lost large parts of their sense of taste, mutations in the receptors in their eyes allow them to see better underwater, and other changes affect oxygen and heat balance.
Another discovery made by Cole and her team is noteworthy. Thus, penguins develop very slowly compared to other birds, and the rate of evolution has decreased further since the appearance of modern penguins. Its development also slows down as it gets warmer. This is suggested by both the evolutionary rates of modern penguins in warm waters and the rates of evolution calculated over the past few million years. The reason for this is still not entirely clear. This raises the question of whether penguins are able to adapt in the long term to the current rapid warming.
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