We wonder what George from Seinfeld would think of this headline. Jokes aside, according to phys.org, University of New Mexico researchers just released a paper that proves a bird's genome shrinks over time in birds that use a lot of their energy while in flight.  The paper is "Metabolic 'engines' of flight drive genome size reduction in birds," and it was published in the Proceedings of the Royal Society B, by UNM Department of Biology graduate student Natalie Wright and Associate Professor Christopher Witt. From phys.org:

Wright and Witt, along with their colleague Ryan Gregory at the University of Guelph, measured the genome sizes of more than 400 bird species from the MSB collection. They examined the sizes of the birds' bodies, flight muscles, hearts, and wings, as well as other characteristics. The muscles and hearts, more than any other characteristic, were linked to genome size. These organs are considered to be the metabolic 'engines' for avian flight. According to the work that Wright has done for her dissertation, the flight muscles can weigh up to one-third of a bird's body weight, and their bulk allows for intense bursts of energy production. The size of the heart sets the upper limit for sustained oxygen consumption because it limits the amount of blood that can be pumped with each beat. "This suggests that intense metabolic activity, such as occurs during flight, has caused the evolution of smaller genomes," said Witt. "The more energy that is required for flight, the more advantage there is to shedding extra DNA content that would otherwise slow down metabolism."

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