Tilapia Genome Sequencing Project

The 3000 species of cichlid fish, also known as tilapia, are found in a variety of habitats in Central and South America, Africa, and India. From an evolutionary point of view, the most interesting cichlid species are the 1500 species that recently diverged in the lakes of East Africa. Remarkably, the cichlids of Lake Tanganyika have diverged into 250 species in the past 6-8 million years, and the 500 Lake Victoria species and the 700 Lake Malawi species diverged in only the past 1 million years. For the scientific community, these species provide a natural mutant screen superior to any chemical mutagenesis. The cichlids are especially diverse in tissues and systems such as the endocrine and nervous systems that are related to the neural crest, a vertebrate-specific developmental germ layer. Cichlids are also valuable model organisms for the study of sex determination evolution, speciation and behavior. The combination of a sequenced tilapia genome and the wide variety of recently evolved cichlid behaviors and morphological traits will provide a unique opportunity to study social dominance, territoriality, sexual selection, and feeding behaviors, as well as a wide variety of neural crest derived traits.

The Broad Institute is generating a high quality draft from a Nile tilapia, Oreochromis niloticus. The Nile tilapia is 10-15 million years diverged from the East African lake cichlids, and provides a good outgroup for the study of the remarkable speciation among the cichlids in those lakes. This will be supplemented by low coverage of three cichlids, one from each of Lake Tanganyika, Lake Victoria, and Lake Malawi. The tilapia genomic resources will not only help researchers address important questions about vertebrate evolution, but will also enable the study of behavior, immunology, and toxicology. They will also contribute to the maintenance and improvement of the tilapia as an important food source in over 100 countries and one of the primary sources of protein in the developing world.