title: Niche divergence facilitated by fine-scale ecological partitioning in a recent cichlid fish adaptive radiation.
abstract: Ecomorphological differentiation is a key feature of adaptive radiations, with a general trend for specialization and niche expansion following divergence. Ecological opportunity afforded by invasion of a new habitat is thought to act as an ecological release, facilitating divergence, and speciation. Here, we investigate trophic adaptive morphology and ecology of an endemic clade of oreochromine cichlid fishes (Alcolapia) that radiated along a herbivorous trophic axis following colonization of an isolated lacustrine environment, and demonstrate phenotype-environment correlation. Ecological and morphological divergence of the Alcolapia species flock are examined in a phylogenomic context, to infer ecological niche occupation within the radiation. Species divergence is observed in both ecology and morphology, supporting the importance of ecological speciation within the radiation. Comparison with an outgroup taxon reveals large-scale ecomorphological divergence but shallow genomic differentiation within the Alcolapia adaptive radiation. Ancestral morphological reconstruction suggests lake colonization by a generalist oreochromine phenotype that diverged in Lake Natron to varied herbivorous morphologies akin to specialist herbivores in Lakes Tanganyika and Malawi.
authors.affiliation: Department of Genetics, Evolution and Environment, University College London, London, WC1E 6BT, United Kingdom.|Current Address: School of Biological Sciences, Bangor University, ECW Building, Deiniol Road, Bangor, Gwynedd, LL57 2UW, Wales, United Kingdom.
authors.forename: Antonia G P
authors.initials: AG
authors.lastname: Ford
authors.affiliation: Naturhistorisches Museum der Burgergemeinde Bern, Bernastrasse 15, 3005, Bern, Switzerland.|Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012, Bern, Switzerland.
authors.forename: Lukas
authors.initials: L
authors.lastname: Rüber
authors.affiliation: NERC Life Sciences Mass Spectrometry Facility, SUERC, Rankine Avenue, Scottish Enterprise Technology Park, East Kilbride, G75 0QF, United Kingdom.
authors.forename: Jason
authors.initials: J
authors.lastname: Newton
authors.affiliation: Department of Biology, University of York, Heslington, York, YO10 5DD, United Kingdom.
authors.forename: Kanchon K
authors.initials: KK
authors.lastname: Dasmahapatra
authors.affiliation: Pact Inc, Lilongwe, Malawi.
authors.forename: John D
authors.initials: JD
authors.lastname: Balarin
authors.affiliation: Department of Genetics, Evolution and Environment, University College London, London, WC1E 6BT, United Kingdom.
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Bruun
authors.affiliation: Department of Genetics, Evolution and Environment, University College London, London, WC1E 6BT, United Kingdom.
authors.forename: Julia J
authors.initials: JJ
authors.lastname: Day
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D005075:Biological Evolution; D023681:Cichlids / Q000033:anatomy & histology* / Q000235:genetics / Q000502:physiology*; D017753:Ecosystem; D005260:Female; D049810:Genetic Speciation; D007630:Kenya; D008297:Male; D017422:Sequence Analysis, DNA; D013636:Tanzania
keywords: Alcolapia; ecomorphology; geometric morphometrics; herbivorous diversification; soda lakes; stable isotopes