title: The social and ecological costs of an 'over-extended' phenotype.
abstract: Extended phenotypes offer a unique opportunity to experimentally manipulate and identify sources of selection acting on traits under natural conditions. The social cichlid fish Neolamprologus multifasciatus builds nests by digging up aquatic snail shells, creating an extended sexual phenotype that is highly amenable to experimental manipulation through addition of extra shells. Here, we find sources of both positive sexual selection and opposing natural selection acting on this trait; augmenting shell nests increases access to mates, but also increases social aggression and predation risk. Increasing the attractiveness of one male also changed social interactions throughout the social network and altered the entire community structure. Manipulated males produced and received more displays from neighbouring females, who also joined augmented male territories at higher rates than unmanipulated groups. However, males in more attractive territories received more aggression from neighbouring males, potentially as a form of social policing. We also detected a significant ecological cost of the 'over-extended' phenotype; heterospecific predators usurped augmented nests at higher rates, using them as breeding sites and displacing residents. Using these natural experiments, we find that both social and ecological interactions generate clear sources of selection mediating the expression of an extended phenotype in the wild.
authors.affiliation: Department of Collective Behaviour Max Planck Institute for Ornithology, University of Konstanz, Konstanz, Germany Laboratory of Animal Sociology, Department of Biology and Geosciences, Graduate School of Science, Osaka City University, Japan Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA lyndonjordan@gmail.com.
authors.forename: Lyndon Alexander
authors.identifier: 0000-0001-6131-9734
authors.initials: LA
authors.lastname: Jordan
authors.affiliation: Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA.
authors.forename: Sean M
authors.initials: SM
authors.lastname: Maguire
authors.affiliation: Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA Institute for Cellular and Molecular Biology, Institute for Neuroscience, The University of Texas at Austin, Austin, TX, USA.
authors.forename: Hans A
authors.initials: HA
authors.lastname: Hofmann
authors.affiliation: Laboratory of Animal Sociology, Department of Biology and Geosciences, Graduate School of Science, Osaka City University, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Kohda
mesh_terms: D000374:Aggression; D000818:Animals; D023681:Cichlids / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*; D005260:Female; D008297:Male; D052586:Mating Preference, Animal; D009425:Nesting Behavior; D010641:Phenotype; D011157:Population Dynamics; D012726:Sexual Behavior, Animal; D012919:Social Behavior
keywords: attractiveness; cichlid; extended phenotype; mate choice; predation; territory