Directional selection has shaped the oral jaws of Lake Malawi cichlid fishes

Publication Type:Journal Article
Year of Publication:2003
Authors:R. C. Albertson, Streelman, J. T. , Kocher, T. D.
Journal:Proceedings of the National Academy of Sciences of the United States of America
Date Published:APR 29
Accession Number:ISI:000182612600053
Keywords:convergence, Evolution, morphology, Perciformes, Pisces, quantitative trait loci, sympatric speciation, Tanganyika, teleostei, victoria

East African cichlid fishes represent one of the most striking examples of rapid and convergent evolutionary radiation among vertebrates. Models of ecological speciation would suggest that functional divergence in feeding morphology has contributed to the origin and maintenance of cichlid species diversity. However, definitive evidence for the action of natural selection has been missing. Here we use quantitative genetics to identify regions of the cichlid genome responsible for functionally important shape differences in the oral jaw apparatus. The consistent direction of effects for individual quantitative trait loci suggest that cichlid jaws and teeth evolved in response to strong, divergent selection. Moreover, several chromosomal regions contain a disproportionate number of quantitative trait loci, indicating a prominent role for pleiotropy or genetic linkage in the divergence of this character complex. Of particular interest are genomic intervals with concerted effects on both the length and height of the lower jaw. Coordinated changes in this area of the oral jaw apparatus are predicted to have direct consequences for the speed and strength of jaw movement. Taken together, our results imply that the rapid and replicative nature of cichlid trophic evolution is the result of directional selection on chromosomal packages that encode functionally linked aspects of the craniofacial skeleton.

URL:file://D:%5CPublications%5CAlbertson_2003-PNAS-v100-Directional%20selection%20has%20shaped%20the%20oral%20jaws%20of%20lake%20Malawi%20cichlid%20fishes.pdf<Go to ISI>://000182612600053
Alternate Journal:P Natl Acad Sci USA

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