The Flight Size

The metabolic intensity of powered flight seems to have caused some bird genomes to shrink.

By | February 5, 2014

FLICKR, STEVE COREYThe size of a flying bird’s genome is tied to the animal’s wing dimensions as well as its heart size, flight muscle mass, and total body mass, a team led by the University of New Mexico’s Natalie Wright has found. The researchers published their findings in Proceedings of the Royal Society B last month (January 29).

Specifically, Wright and her colleagues found in a phylogenetically diverse sampling of 422 flying bird species that genome size was negatively correlated with relative flight muscle size and heart-to-body mass ratioand positively correlated with body mass and wing loading. Overall, the researchers noted, large hearts and flight muscles were the best predictors of reduced genome size in birds like the wandering albatross (Diomedea exulans). “These two components of the metabolic flight ‘engine’ implicate the rate of energy use as a key driver of repeated evolutionary reductions in avian genome size,” the authors wrote in their paper.

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Avatar of: Hugh-F-61


Posts: 69

February 7, 2014

Phosphorus atoms are some of the densest atoms in living organisms, and make DNA a significant contribution to body mass. It  makes perfect sense for birds that depend most on efficient flight (as shown by their heart and wing muscle specialisation) should be most highly selected to reduce body mass. Loss of junk DNA ( disposable or surplus DNA if you don't like the term junk) is a distinct evolutionary advantage in these birds, and fits with the evolution of lightweight bones, which are mineralised with calcium phosphate.

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