That's the conclusion drawn by two Rice University scientists who have designed a computer simulation to test the idea that evolvability -- the likelihood of genetic mutation -- is a trait that can itself be favored or disfavored through the process of natural selection.

The results of the study appear in the Aug. 10 issue of Proceedings of the National Academy of Sciences.

Researchers Michael Deem, the John W. Cox Professor of Bioengineering and professor of physics and astronomy, and David Earl, Deem's post-doctoral research fellow, drew their conclusions from a sophisticated computer simulation that recorded how much and how rapidly proteins mutated based on external changes in their environment. As the researchers ramped up the frequency and severity of environmental changes -- imagine rapid shifts between heat waves and cold snaps or heavy rains and droughts -- they saw an increased likelihood of survival among proteins that mutated more frequently.

"Selection for evolvability would help explain a growing body of experimental results including the evolution of drug resistance in bacteria, the fact that some immune system cells mutate much more rapidly than other cells in our bodies, as well as why some bacteria and higher-order organisms have a tendency to transpose or swap relatively long sequences of DNA," said Deem.

Traditionally, a significant number of evolutionary biologists have discounted the idea that evolvability is subject to natural selection, in part because the idea that evolution acts upon the mechanism that causes evolution seems to violate the basic scientific principle that an event cannot precede its own cause.

But Deem and Earl argue that causal violations need not occur. For one thing, there are several different ways that genetic mutations occur. Random changes along the DNA chain are now understood to
'"/>

Contact: Jade Boyd
jadeboyd@rice.edu
713-348-6778
Rice University
9-Aug-2004