Integration and Evolution of the Cichlid Mandible: The Molecular Basis of Alternate Feeding Strategies

African cichlid fishes have repeatedly evolved highly specialized modes of feeding through adaptations of their oral jaws. Here, we explore the molecular genetic basis of the opening and closing lever mechanisms of the cichlid lower jaw, which have traditionally been used to describe the mechanics o...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2005-11, Vol.102 (45), p.16287-16292
Main Authors: Albertson, R. Craig, Streelman, J. Todd, Kocher, Thomas D., Yelick, Pamela C.
Format: Article
Language:English
Subjects:
Adaptation
Animal behavior
Animals
Biological Evolution
Biological Sciences
Bone Morphogenetic Protein 4
Bone Morphogenetic Proteins - physiology
Cartilage
Cichlidae
Cichlids - anatomy & histology
Cichlids - genetics
Cichlids - physiology
Danio rerio
Embryos
Evolution
Evolutionary genetics
Feeding Behavior
Fish
Freshwater
Genotype & phenotype
Jaw
Mandible
Mandible - anatomy & histology
Mandible - physiology
Messenger RNA
Morphogenesis
Phenotypic traits
Quantitative Trait Loci
Species Specificity
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Summary:African cichlid fishes have repeatedly evolved highly specialized modes of feeding through adaptations of their oral jaws. Here, we explore the molecular genetic basis of the opening and closing lever mechanisms of the cichlid lower jaw, which have traditionally been used to describe the mechanics of feeding behavior in bony fishes. Quantitative genetic analyses demonstrate that the opening and closing mechanisms are genetically modular and therefore free to evolve independently. Bmp4 (bone morphogenetic protein 4) is one of two loci that segregate with the mechanical advantage of closing and that together account for >30% of the phenotypic variance in this trait. Species-specific differences in jaw shape are obvious early in cichlid larval development and are correlated with patterns of bmp4 expression in the mandibular primordium. When bmp4 is overexpressed in the obligate suction feeder Danio rerio, mandibular morphology exhibits specific transformations of opening and closing lever ratios. We conclude that patterns of morphological integration of the cichlid jaw reflect a balance among conflicting functional demands. Further, we demonstrate that bmp4 has the potential to alter mandibular morphology in a way that mimics adaptive variation among fish species.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0506649102