title: Self-recognition, color signals, and cycles of greenbeard mutualism and altruism.
abstract: Altruism presents a challenge to evolutionary theory because selection should favor selfish over caring strategies. Greenbeard altruism resolves this paradox by allowing cooperators to identify individuals carrying similar alleles producing a form of genic selection. In side-blotched lizards, genetically similar but unrelated blue male morphs settle on adjacent territories and cooperate. Here we show that payoffs of cooperation depend on asymmetric costs of orange neighbors. One blue male experiences low fitness and buffers his unrelated partner from aggressive orange males despite the potential benefits of defection. We show that recognition behavior is highly heritable in nature, and we map genetic factors underlying color and self-recognition behavior of genetic similarity in both sexes. Recognition and cooperation arise from genome-wide factors based on our mapping study of the location of genes responsible for self-recognition behavior, recognition of blue color, and the color locus. Our results provide an example of greenbeard interactions in a vertebrate that are typified by cycles of greenbeard mutualism interspersed with phases of transient true altruism. Such cycles provide a mechanism encouraging the origin and stability of true altruism.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California, Earth and Marine Sciences Building, Santa Cruz, CA 95064, USA. sinervo@biology.ucsc.edu
authors.forename: Barry
authors.initials: B
authors.lastname: Sinervo
authors.forename: Alexis
authors.initials: A
authors.lastname: Chaine
authors.forename: Jean
authors.initials: J
authors.lastname: Clobert
authors.forename: Ryan
authors.initials: R
authors.lastname: Calsbeek
authors.forename: Lisa
authors.initials: L
authors.lastname: Hazard
authors.forename: Lesley
authors.initials: L
authors.lastname: Lancaster
authors.forename: Andrew G
authors.initials: AG
authors.lastname: McAdam
authors.forename: Suzanne
authors.initials: S
authors.lastname: Alonzo
authors.forename: Gwynne
authors.initials: G
authors.lastname: Corrigan
authors.forename: Michael E
authors.initials: ME
authors.lastname: Hochberg
mesh_terms: D000533:Altruism; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D005075:Biological Evolution; D003116:Color; D004532:Ego; D016678:Genome; D008116:Lizards / Q000502:physiology; D008297:Male; D010858:Pigmentation / Q000235:genetics / Q000502:physiology*