title: Testing for ancient adaptive radiations in neotropical cichlid fishes.
abstract: Most contemporary studies of adaptive radiation focus on relatively recent and geographically restricted clades. It is less clear whether diversification of ancient clades spanning entire continents is consistent with adaptive radiation. We used novel fossil calibrations to generate a chronogram of Neotropical cichlid fishes and to test whether patterns of lineage and morphological diversification are congruent with hypothesized adaptive radiations in South and Central America. We found that diversification in the Neotropical cichlid clade and the highly diverse tribe Geophagini was consistent with diversity-dependent, early bursts of divergence followed by decreased rates of lineage accumulation. South American Geophagini underwent early rapid differentiation in body shape, expanding into novel morphological space characterized by elongate-bodied predators. Divergence in head shape attributes associated with trophic specialization evolved under strong adaptive constraints in all Neotropical cichlid clades. The South American Cichlasomatini followed patterns consistent with constant rates of morphological divergence. Although morphological diversification in South American Heroini was limited, Eocene invasion of Central American habitats was followed by convergent diversification mirroring variation observed in Geophagini. Diversification in Neotropical cichlids was influenced by the early adaptive radiation of Geophagini, which potentially limited differentiation in other cichlid clades.
authors.affiliation: Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada. hernanl@rom.on.ca
authors.forename: Hernán
authors.initials: H
authors.lastname: López-Fernández
authors.forename: Jessica H
authors.initials: JH
authors.lastname: Arbour
authors.forename: Kirk O
authors.initials: KO
authors.lastname: Winemiller
authors.forename: Rodney L
authors.initials: RL
authors.lastname: Honeycutt
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics*; D000818:Animals; D023681:Cichlids / Q000145:classification / Q000235:genetics*; D019143:Evolution, Molecular; D005580:Fossils; D049810:Genetic Speciation; D010802:Phylogeny