Penguins are an amazing group of flightless bird that have fascinated the public and scientists alike. These cute creatures have captivated people with their funny walks and incredible life histories. A study recently published in Biology Letters has offered estimates for when the common ancestor of modern penguins lived and when penguins diverged into different species – new timelines that are half the time as some previous estimates.
There has been controversy and great variation between the estimates of this study and previous studies based on the methods used to reach them. Using only the fossil record, scientists can conclude that penguin species diverged at a time far from one reached through DNA analysis. The new Biology Letters study used sequenced DNA from all 11 living genera of penguins and the fossil record of penguins to “calibrate the molecular clock.” Through this, it was estimated that the common ancestor that led to all modern penguins is about 20 million years old and that penguins started to diverge into their separate lineages approximately 11-16 million years ago.
An interesting twist to this story is that there have been fossils found that are penguin-like dated at 62 million years old. This drastically predates when the first ancestors of modern day penguins appeared, creating a “gap” in the penguin’s evolutionary history. Sankar Subramanian, lead author of the study, commented on this: “The big gap between these two times raises questions like: What happened to the older lineages of penguins? What caused the extinction of all other older lineages? Could that be due to any change in Antarctic or global climate?”
Approximately 12 million years ago, there was a well-documented climate change event in the Antarctic. There is no proof that the divergence estimates of 11-16 million years ago given by the study and the event are linked. However, it is possible that a changing environment would have made it advantageous for certain groups of penguins to develop different traits to help them cope with the changing environmental conditions. This could have led to the wide geographic range of habitats and broad variance of traits that are seen in today’s penguins.
Source: Subramanian, S., Beans-Picón, G., Swaminathan, S. K., Millar, C. D., & Lambert, D. M. (2013). Evidence for a recent origin of penguins. Biology Letters, 9(6), 20130748.
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