title: Comparative rates of lower jaw diversification in cichlid adaptive radiations.
abstract: The lower jaw (LJ) provides an ideal trophic phenotype to compare rates and patterns of macroevolution among cichlid radiations. Using a novel phylogeny of four genes (ND2, dlx2, mitfb, and s7), we examined the evolutionary relationships among two of the most phylogenetically disparate cichlid radiations: (i) the Central America Heroines; and (ii) the East African Lake Malawi flock. To quantify jaw morphology, we measured two LJ lever systems in approximately 40 species from each lineage. Using geologic calibrations, we generated a chronogram for both groups and examined the rates of jaw evolution in the two radiations. The most rapidly evolving components of the LJ differed between the two radiations. However, the Lake Malawi flock exhibited a much faster rate of evolution in several components of the LJ. This rapid rate of divergence is consistent with natural selection, promoting unparalleled trophic diversification in Lake Malawi cichlids.
authors.affiliation: Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996, USA. chulsey@utk.edu
authors.forename: C D
authors.initials: CD
authors.lastname: Hulsey
authors.forename: M C
authors.initials: MC
authors.lastname: Mims
authors.forename: N F
authors.initials: NF
authors.lastname: Parnell
authors.forename: J T
authors.initials: JT
authors.lastname: Streelman
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D001499:Bayes Theorem; D005075:Biological Evolution; D001837:Body Weights and Measures; D002489:Central America; D023681:Cichlids / Q000033:anatomy & histology* / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D049810:Genetic Speciation; D008295:Malawi; D008334:Mandible / Q000033:anatomy & histology*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D017931:DNA Primers