title: Rugged adaptive landscapes shape a complex, sympatric radiation.
abstract: Strong disruptive ecological selection can initiate speciation, even in the absence of physical isolation of diverging populations. Species evolving under disruptive ecological selection are expected to be ecologically distinct but, at least initially, genetically weakly differentiated. Strong selection and the associated fitness advantages of narrowly adapted individuals, coupled with assortative mating, are predicted to overcome the homogenizing effects of gene flow. Theoretical plausibility is, however, contrasted by limited evidence for the existence of rugged adaptive landscapes in nature. We found evidence for multiple, disruptive ecological selection regimes that have promoted divergence in the sympatric, incipient radiation of 'sharpfin' sailfin silverside fishes in ancient Lake Matano (Sulawesi, Indonesia). Various modes of ecological specialization have led to adaptive morphological differences between the species, and differently adapted morphs display significant but incomplete reproductive isolation. Individual fitness and variation in morphological key characters show that disruptive selection shapes a rugged adaptive landscape in this small but complex incipient lake fish radiation.
authors.affiliation: Sektion Ichthyologie, Zoologisches Forschungsmuseum Alexander Koenig, Adenauerallee 160, Bonn 53113, Germany Museum für Naturkunde Berlin, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, Berlin 10115, Germany j.pfaender@zfmk.de.
authors.forename: Jobst
authors.initials: J
authors.lastname: Pfaender
authors.affiliation: Ichthyology Laboratory, Division of Zoology, Research Center for Biology, Indonesian Institute of Sciences (LIPI), Jl. Raya Bogor Km 46, Cibinong 16911, Indonesia.
authors.forename: Renny K
authors.initials: RK
authors.lastname: Hadiaty
authors.affiliation: Department of Ichthyology, SNSB - Bavarian State Collection of Zoology (ZSM), Münchhausenstr. 21, München 81247, Germany.
authors.forename: Ulrich K
authors.initials: UK
authors.lastname: Schliewen
authors.affiliation: Sektion Ichthyologie, Zoologisches Forschungsmuseum Alexander Koenig, Adenauerallee 160, Bonn 53113, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Herder
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D017753:Ecosystem; D005247:Feeding Behavior; D005399:Fishes / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*; D049810:Genetic Speciation; D014644:Genetic Variation; D005843:Geography; D007214:Indonesia; D010641:Phenotype; D012641:Selection, Genetic
keywords: Telmatherina; adaptive landscapes; adaptive radiation; disruptive selection; ecological speciation; sympatric speciation