East African Cichlid Fish Offer New Understanding of Genetic Basis of Sex Determination

Biologists have genetically mapped the sex chromosomes of several species of cichlid fish from Lake Malawi, East Africa, and identified a mechanism by which new sex chromosomes may evolve.

In research published in this week's issue of the journal Science, biologists Thomas Kocher, Reade Roberts and Jennifer Ser of the University of Maryland describe the genetic basis for two co-existing systems of sexual determination in cichlid fish from Lake Malawi.

"This study marries two evolutionary mysteries: the incredible diversity of fish in the lakes of East Africa and the genetic basis of sex determination," says Sam Scheiner, program director in the National Science Foundation (NSF)'s Division of Environmental Biology, which funded the research. "Simple genetic changes can lead to enormous biological diversity."

The thousands of closely related cichlid fishes in the lakes of East Africa turn out to be an excellent model system for understanding how the mechanisms of sex determination evolve.

Image credit: Reade Roberts