title: The evolution of jaw protrusion mechanics is tightly coupled to bentho-pelagic divergence in damselfishes (Pomacentridae).
abstract: Most species-rich lineages of aquatic organisms have undergone divergence between forms that feed from the substrate (benthic feeding) and forms that feed from the water column (pelagic feeding). Changes in trophic niche are frequently accompanied by changes in skull mechanics, and multiple fish lineages have evolved highly specialized biomechanical configurations that allow them to protrude their upper jaws toward the prey during feeding. Damselfishes (family Pomacentridae) are an example of a species-rich lineage with multiple trophic morphologies and feeding ecologies. We sought to determine whether bentho-pelagic divergence in the damselfishes is tightly coupled to changes in jaw protrusion ability. Using high-speed video recordings and kinematic analysis, we examined feeding performance in 10 species that include three examples of convergence on herbivory, three examples of convergence on omnivory and two examples of convergence on planktivory. We also utilized morphometrics to characterize the feeding morphology of an additional 40 species that represent all 29 damselfish genera. Comparative phylogenetic analyses were then used to examine the evolution of trophic morphology and biomechanical performance. We find that pelagic-feeding damselfishes (planktivores) are strongly differentiated from extensively benthic-feeding species (omnivores and herbivores) by their jaw protrusion ability, upper jaw morphology and the functional integration of upper jaw protrusion with lower jaw abduction. Most aspects of cranial form and function that separate these two ecological groups have evolved in correlation with each other and the evolution of the functional morphology of feeding in damselfishes has involved repeated convergence in form, function and ecology.
authors.affiliation: School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA 99164, USA jim.cooper@wsu.edu.
authors.forename: W James
authors.identifier: 0000-0003-4204-4266
authors.initials: WJ
authors.lastname: Cooper
authors.affiliation: School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA 99164, USA.
authors.forename: Casey B
authors.initials: CB
authors.lastname: Carter
authors.affiliation: Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts, 204C French Hall, University of Massachusetts Amherst, 230 Stockbridge Road, Amherst, MA 01003, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Conith
authors.affiliation: Bioacoustics Research Program, Cornell Lab of Ornithology, Cornell University, 159 Sapsucker Woods Road, Ithaca, NY 14850, USA.
authors.forename: Aaron N
authors.initials: AN
authors.lastname: Rice
authors.affiliation: Department of Organismal Biology and Anatomy, The University of Chicago, 1027 E. 57th St., Chicago, IL 60637, USA.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Westneat
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D005075:Biological Evolution; D001696:Biomechanical Phenomena; D005247:Feeding Behavior; D007568:Jaw / Q000033:anatomy & histology / Q000502:physiology; D010473:Perciformes / Q000033:anatomy & histology* / Q000235:genetics / Q000502:physiology*; D010802:Phylogeny
keywords: Coral reef; Diet niche; Ecomorphology; Feeding kinematics; Functional morphology; Reticulate adaptive radiation