The penguins are best known for their flightless nature and their ability to fly through cold waters. Sixty million years ago, penguins lost their ability to fly and instead became streamlined swimmers, and researchers now know how that happened.
A new study of penguin fossils and the genomes of current and recently extinct penguins identified an array of genetic alterations the birds made to live an aquatic lifestyle, from vision that is sensitive to underwater blue tones to genes related to blood oxygenation. The findings show that penguins were able to survive some serious environmental changes that occurred over millions of years.
According to study co-author Daniel Ksepka, the oldest penguin fossils are 62 million years old. The penguins looked very different from the modern penguins. They had long legs and beaks and were more winglike than flippers.
"These early ones are probably evolving from a bird that can still fly through the air," Ksepka said. It's not known when penguins lost their aerial abilities, because this flying ancestor hasn't been discovered in the fossil record.
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Over time, evolution created penguins with long spear-like bills, penguins with red feathers, penguins that stood a foot or two taller than the emperor, and penguins with long spear-like bills.
Fossil evidence and partial genomes of penguins that went extinct within the past few hundred years were evaluated. According to the findings, penguins came to New Zealand around 60 million years ago and then traveled to South America and then back to New Zealand. The last 2 million years have seen the divergence of most species. In the past, Earth has gone through periods in which the polar ice expanded and retreated. Advancing ice pushed penguins northward so they could take their own evolutionary paths for about 100,000 years. The penguins had evolved into different species when the ice retreated.
It doesn't affect all species equally, but it's almost like someone is making more penguins.
The researchers reported in the journal Nature Communications that penguins have the lowest evolutionary rate of change of any bird. Ksepka said this was surprising and remained unexplained. Smaller animals tend to have slower evolutionary rates than larger ones. Some birds are bigger than others. penguins are so slow to evolve that more work is needed to understand why they are so slow to evolve.
penguin evolution is comparatively slow but it has provided them with many adaptions for life in and near the sea They share a suite of genes with other flightless birds that shortened their wings, and they also have unique genes that may have made them flippers. The dense bones that help penguins to dive may be due to the fact that the genes associated with calcium storage are missing.
Genes associated with fat storage and temperature regulation have been altered by evolution. penguins lost a number of genes early on in their evolution that were related to their ability to digest crustaceans It's possible that early penguins had a diet of fish and squid. The expansion of the ice sheets resulted in a rich environment for small crustaceans. The CHIA genes allowed penguins to still digest crustaceans.
They may have had a hard time swallowing if that last one had stopped.
Climate change may cause about 75% of the penguin species to be extinct. Emperor penguins breed entirely on sea ice, so this is true for them. Emperor penguins may not be able to find breeding grounds if sea ice goes away. On the other side of the spectrum, tiny penguins that live in the rocky islands have nowhere to go if their habitat gets too hot.
Many of the animals are already considered to be extinct due to environmental change. They could become more vulnerable over time.
It was originally published on Live Science
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