Some fish really know how to swim to the top. Researchers have found that within minutes of recognizing a social void, a lowly cichlid can alter its looks and behavior to ascend to the dominant spot in its group. Moreover, the same researchers have identified the gene that is primarily responsible for the fish's changing physiology.
"We had known that social environment controls the reproduction of [cichlids]," says Sabrina Burmeister of the University of North Carolina at Chapel Hill. Other researchers had shown, for example, that a subordinate male, normally sterile, can gain the ability to reproduce within a week of the removal of the dominant male. In the November PLoS Biology, Burmeister shows that the color and behavior of an upwardly mobile