But now scientists studying a species of African cichlid fish have discovered that low-ranking male cichlids can quickly become leading men without even putting up a fight. In fact, a drab subordinate male cichlid will begin physically transforming into a colorful dominant male as soon as he notices that his competition is no longer around, according to a new study conducted at Stanford University.

"We show for the first time that subordinate males can become dominant within minutes of an opportunity to do so, displaying dramatic changes in body coloration and behavior," write neurobiologists Sabrina Burmeister, Erich Jarvis and Russell Fernald, co-authors of the study published in the Oct. 17 edition of the journal PloS Biology. During this radical makeover, the low-ranking male undergoes a rapid metamorphosis. His body color changes from dull gray to flashy blue or yellow, and a prominent black stripe ("eyebar") appears across his face. This physical transformation signals to males and females alike that he's the top fish now and will vigorously defend his newly acquired breeding grounds.

"We found that when the dominating male is removed, the subordinate male perceives an opportunity to advance in social status and responds both behaviorally and by turning on genes that ultimately make him capable of reproducing," notes Fernald, the Benjamin Scott Crocker Professor of Human Biology at Stanford. This finding offers the first direct evidence that changes in social status also trigger cellular and molecular changes in the brain, he adds, which could have significant implications for understanding how other vertebrates, including humans, respond to social information.

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Contact: Mark Shwartz
mshwartz@stanford.edu
650-723-9296
Stanford University
17-Oct-2005