title: Fluctuations in Evolutionary Integration Allow for Big Brains and Disparate Faces.
abstract: In theory, evolutionary modularity allows anatomical structures to respond differently to selective regimes, thus promoting morphological diversification. These differences can then influence the rate and direction of phenotypic evolution among structures. Here we use geometric morphometrics and phenotypic matrix statistics to compare rates of craniofacial evolution and estimate evolvability in the face and braincase modules of a clade of teleost fishes (Gymnotiformes) and a clade of mammals (Carnivora), both of which exhibit substantial craniofacial diversity. We find that the face and braincase regions of both clades display different degrees of integration. We find that the face and braincase evolve at similar rates in Gymnotiformes and the reverse in Carnivora with the braincase evolving twice as fast as the face. Estimates of evolvability and constraints in these modules suggest differential responses to selection arising from fluctuations in phylogenetic integration, thus influencing differential rates of skull-shape evolution in these two clades.
authors.affiliation: University of Louisiana at Lafayette, Department of Biology, P.O. Box 42451, Lafayette, LA, 70504, USA.
authors.forename: Kory M
authors.initials: KM
authors.lastname: Evans
authors.affiliation: University of Louisiana at Lafayette, Department of Biology, P.O. Box 42451, Lafayette, LA, 70504, USA.
authors.forename: Brandon T
authors.initials: BT
authors.lastname: Waltz
authors.affiliation: Universidade Federal do Tocantins, Programa de Pós-graduação Ciências do Ambiente (CIAMB), Palmas, Tocantins, 77001-090, Brazil.
authors.forename: Victor A
authors.initials: VA
authors.lastname: Tagliacollo
authors.affiliation: Oregon State University, Department of Fisheries and Wildlife, 104 Nash Hall, Corvallis, OR, 97331, USA.
authors.forename: Brian L
authors.initials: BL
authors.lastname: Sidlauskas
authors.affiliation: University of Louisiana at Lafayette, Department of Biology, P.O. Box 42451, Lafayette, LA, 70504, USA.
authors.forename: James S
authors.initials: JS
authors.lastname: Albert
mesh_terms: D000818:Animals; D044822:Biodiversity; D005075:Biological Evolution; D001921:Brain / Q000033:anatomy & histology*; D002335:Carnivora / Q000033:anatomy & histology*; D003198:Computer Simulation; D005145:Face / Q000033:anatomy & histology*; D005399:Fishes / Q000033:anatomy & histology*; D016018:Least-Squares Analysis; D009929:Organ Size; D010802:Phylogeny; D012641:Selection, Genetic