ScienceDaily has a story describing a new paper showing that the rate of protein evolution is subject to allometric scaling. Actually, now that I have written that, I remember that allometric scaling describes a specfic mathematical relationship between metabolism and body mass, but the paper in question doesn't appear to be online yet so I can't say for sure allometric scaling is the appropriate mechanism to cite.
At any rate, ScienceDaily reports that James Gillooly, and colleagues have shown that: "...A 10-degree increase in temperature across species leads to about a 300 percent increase in the evolutionary rate of proteins, while a tenfold decrease in body size leads to about a 200 percent increase in evolutionary rates."
"Generally, there are two schools of thought about what affects evolution," said Andrew P. Allen, Ph.D., a researcher with the National Center for Ecological Analysis and Synthesis in Santa Barbara, Calif. "One says the environment dictates changes that occur in the genome and phenotype of a species, and the other says the DNA mutation rate drives these changes. Our findings suggest physiological processes that drive mutation rates are important."
That is pretty interesting. Warm, small animals evidently experience a greater rate of protein evolution than to large, cold ones. This suggests to me that warm-blooded, smaller animals have an evolutionary advantage because they are better able to produce physiological variation in the context of a changing environment, and thus better able to compete at the species level in the face of natural selection. The ScienceDaily story doesn't make that point, but I would assume the paper in Biology Letters, when it is published, will.
Here is the press release from the University of Florida.