Dr. Sabrina S. Burmeister, assistant professor of biology at the University of North Carolina at Chapel Hill's College of Arts and Sciences, and colleagues found that subordinate male fish underwent a radical and rapid transformation when more dominant males were removed.
"When we took dominant cichlid males from an experimental tank, subordinate males started becoming dominant themselves in as few as two minutes," Burmeister said. "Their colors -- blue and yellow -- got much brighter, a black stripe we call an eye bar appeared near their eyes, and they became much more aggressive than they were before. The remaining males also quickly paid a lot more attention to females because for the first time, they had an opportunity to reproduce."
No one had any idea before that perceived changes in their social status could begin altering animals' behavior and appearance so quickly, she said. Previous studies had shown the changes took as long as a week and were associated with increased fertility.
Burmeister's report on her experiments, conducted at Stanford University, appears in the November issue of the scientific journal PloS Biology, which is being released today (Oct. 17). Co-authors are Drs. Erich D. Jarvis and Russell D. Fernald, neurobiologists at Duke University and Stanford, respectively.
The research is part of a larger effort to understand some of the most intriguing questions in all of biology -- how did brains evolve and how can the environment change an animal's physiology through actions on its brain?
Such studies are relevant to humans since the hormones and genes involved are close to identical, she said. Obviously, such internal gene activity studies canno
Contact: David Williamson
University of North Carolina at Chapel Hill