title: Testing the stages model in the adaptive radiation of cichlid fishes in East African Lake Tanganyika.
abstract: Adaptive radiation (AR) is a key process in the origin of organismal diversity. However, the evolution of trait disparity in connection with ecological specialization is still poorly understood. Available models for vertebrate ARs predict that diversification occurs in the form of temporal stages driven by different selective forces. Here, we investigate the AR of cichlid fishes in East African Lake Tanganyika and use macroevolutionary model fitting to evaluate whether diversification happened in temporal stages. Six trait complexes, for which we also provide evidence of their adaptiveness, are analysed with comparative methods: body shape, pharyngeal jaw shape, gill raker traits, gut length, brain weight and body coloration. Overall, we do not find strong evidence for the 'stages model' of AR. However, our results suggest that trophic traits diversify earlier than traits implicated in macrohabitat adaptation and that sexual communication traits (i.e. coloration) diversify late in the radiation.
authors.affiliation: Zoological Institute, University of Basel, Basel 4051, Switzerland Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
authors.forename: Moritz
authors.initials: M
authors.lastname: Muschick
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
authors.forename: Patrik
authors.initials: P
authors.lastname: Nosil
authors.affiliation: Zoological Institute, University of Basel, Basel 4051, Switzerland.
authors.forename: Marius
authors.initials: M
authors.lastname: Roesti
authors.affiliation: Institute of Agricultural Sciences, ETH Zurich, Zürich 8092, Switzerland Clinic for Zoo Animals, Wildlife and Exotic Pets, Vetsuisse Faculty, University of Zurich, Zürich 8057, Switzerland.
authors.forename: Marie Theres
authors.initials: MT
authors.lastname: Dittmann
authors.affiliation: Department of Biological Sciences and Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho, Moscow, ID, USA.
authors.forename: Luke
authors.initials: L
authors.lastname: Harmon
authors.affiliation: Zoological Institute, University of Basel, Basel 4051, Switzerland walter.salzburger@unibas.ch.
authors.forename: Walter
authors.initials: W
authors.lastname: Salzburger
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D005075:Biological Evolution; D023681:Cichlids / Q000502:physiology*; D049810:Genetic Speciation; D060106:Lakes; D008957:Models, Genetic; D010802:Phylogeny; D015024:Zambia
keywords: convergence; ecological specialization; gill raker; niche overlap; trait evolution