Warmer world may mean smaller animals

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LONDON, Sept. 27 (UPI) -- Many animal species could shrink in physical size as an unanticipated consequence of global warming, British researchers say.

Cold-blooded species have long been known to react to a phenomenon known as the "temperature-size rule," in which individuals of the same species reach a smaller adult size when reared at warmer temperatures. Researchers at Queen Mary, University of London say they've discovered how and why that occurs.

The scientists say in many cold-blooded species, the growth rate, or how fast mass is accumulated, and the development rate, how fast an individual passes through its life stages, are consistently "decoupled," with development being more sensitive to temperature than growth.

"We've shown that growth and development increase at different rates as temperatures warm," researchers Andrew Hirst said. "The consequences are that at warmer temperatures a species grows faster but matures even faster still, resulting in them achieving a smaller adult size."

The researchers say their findings suggest rates fundamental to all organisms -- such as mortality, reproduction and feeding -- may not change in synch with one another in a warming world.