title: Comparative tests of the role of dewlap size in Anolis lizard speciation.
abstract: Phenotypic traits may be linked to speciation in two distinct ways: character values may influence the rate of speciation or diversification in the trait may be associated with speciation events. Traits involved in signal transmission, such as the dewlap of Anolis lizards, are often involved in the speciation process. The dewlap is an important visual signal with roles in species recognition and sexual selection, and dewlaps vary among species in relative size as well as colour and pattern. We compile a dataset of relative dewlap size digitized from photographs of 184 anole species from across the genus' geographical range. We use phylogenetic comparative methods to test two hypotheses: that larger dewlaps are associated with higher speciation rates, and that relative dewlap area diversifies according to a speciational model of evolution. We find no evidence of trait-dependent speciation, indicating that larger signals do not enhance any role the dewlap has in promoting speciation. Instead, we find a signal of mixed speciational and gradual trait evolution, with a particularly strong signal of speciational change in the dewlaps of mainland lineages. This indicates that dewlap size diversifies in association with the speciation process, suggesting that divergent selection may play a role in the macroevolution of this signalling trait.
authors.affiliation: Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA travis.ingram@otago.ac.nz.
authors.forename: Travis
authors.identifier: 0000-0003-0709-5260
authors.initials: T
authors.lastname: Ingram
authors.affiliation: Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA.
authors.forename: Alexis
authors.initials: A
authors.lastname: Harrison
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, 3031, Toronto, Ontario, Canada M5S 3B2.
authors.forename: D Luke
authors.initials: DL
authors.lastname: Mahler
authors.affiliation: Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA.
authors.forename: María Del Rosario
authors.initials: MD
authors.lastname: Castañeda
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS 66045, USA.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Glor
authors.affiliation: Département d'Ecologie et de Gestion de la Biodiversité, UMR 7179 C.N.R.S/M.N.H.N., 57 rue Cuvier, Case postale 55, 75231 Paris Cedex 5, France.
authors.forename: Anthony
authors.initials: A
authors.lastname: Herrel
authors.affiliation: Department of Integrative Biology, University of Texas at Austin, One University Station C0990, Austin, TX 78712, USA.
authors.forename: Yoel E
authors.initials: YE
authors.lastname: Stuart
authors.affiliation: Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA.
authors.forename: Jonathan B
authors.initials: JB
authors.lastname: Losos
mesh_terms: D000818:Animals; D049810:Genetic Speciation; D005843:Geography; D008116:Lizards / Q000033:anatomy & histology* / Q000145:classification; D009333:Neck / Q000033:anatomy & histology*; D010641:Phenotype; D010802:Phylogeny; D012867:Skin / Q000033:anatomy & histology*
keywords: signalling trait; speciational trait evolution; species recognition; trait-dependent diversification