title: Assessing multivariate constraints to evolution across ten long-term avian studies.
abstract: BACKGROUND
  In a rapidly changing world, it is of fundamental importance to understand processes constraining or facilitating adaptation through microevolution. As different traits of an organism covary, genetic correlations are expected to affect evolutionary trajectories. However, only limited empirical data are available.
  
  
  RESULTS
  We investigate the extent to which multivariate constraints affect the rate of adaptation, focusing on four morphological traits often shown to harbour large amounts of genetic variance and considered to be subject to limited evolutionary constraints. Our data set includes unique long-term data for seven bird species and a total of 10 populations. We estimate population-specific matrices of genetic correlations and multivariate selection coefficients to predict evolutionary responses to selection. Using Bayesian methods that facilitate the propagation of errors in estimates, we compare (1) the rate of adaptation based on predicted response to selection when including genetic correlations with predictions from models where these genetic correlations were set to zero and (2) the multivariate evolvability in the direction of current selection to the average evolvability in random directions of the phenotypic space. We show that genetic correlations on average decrease the predicted rate of adaptation by 28%. Multivariate evolvability in the direction of current selection was systematically lower than average evolvability in random directions of space. These significant reductions in the rate of adaptation and reduced evolvability were due to a general nonalignment of selection and genetic variance, notably orthogonality of directional selection with the size axis along which most (60%) of the genetic variance is found.
  
  
  CONCLUSIONS
  These results suggest that genetic correlations can impose significant constraints on the evolution of avian morphology in wild populations. This could have important impacts on evolutionary dynamics and hence population persistence in the face of rapid environmental change.
authors.affiliation: Département Ecologie et Gestion de la Biodiversité UMR 7204 CNRS/MNHN/UPMC, Muséum National d'Histoire Naturelle, Paris, France.
authors.forename: Celine
authors.initials: C
authors.lastname: Teplitsky
authors.affiliation: Department of Biology, Lund University, Ecology Building, Lund, Sweden.
authors.forename: Maja
authors.initials: M
authors.lastname: Tarka
authors.affiliation: Laboratoire d'Ecologie, Systématique et Evolution, CNRS UMR 8079, Université Paris-Sud, Orsay, France.
authors.forename: Anders P
authors.initials: AP
authors.lastname: Møller
authors.affiliation: Department of Zoology, University of Otago, Dunedin, New Zealand.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Nakagawa
authors.affiliation: Department of Zoology, Biology Building, University of Seville, Seville, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Balbontín
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom.
authors.forename: Terry A
authors.initials: TA
authors.lastname: Burke
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive UMR 5175 CNRS, Montpellier, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Doutrelant
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive UMR 5175 CNRS, Montpellier, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Gregoire
authors.affiliation: Department of Biology, Lund University, Ecology Building, Lund, Sweden.
authors.forename: Bengt
authors.initials: B
authors.lastname: Hansson
authors.affiliation: Department of Biology, Lund University, Ecology Building, Lund, Sweden.
authors.forename: Dennis
authors.initials: D
authors.lastname: Hasselquist
authors.affiliation: Department of Animal Ecology, Evolutionary Biology Center, Uppsala University, Uppsala, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Gustafsson
authors.affiliation: Departamento de Zoología, Universidad de Extremadura, Badajoz, Spain.
authors.forename: Florentino
authors.initials: F
authors.lastname: de Lope
authors.affiliation: Departamento de Zoología, Universidad de Extremadura, Badajoz, Spain.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Marzal
authors.affiliation: Corning, New York, United States of America.
authors.forename: James A
authors.initials: JA
authors.lastname: Mills
authors.affiliation: Department of Biology, Bowdoin College, Brunswick, Maine, United States of America.
authors.forename: Nathaniel T
authors.initials: NT
authors.lastname: Wheelwright
authors.affiliation: Lincoln, Christchurch, New Zealand.
authors.forename: John W
authors.initials: JW
authors.lastname: Yarrall
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive UMR 5175 CNRS, Montpellier, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Charmantier
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001499:Bayes Theorem; D005075:Biological Evolution; D001717:Birds / Q000235:genetics / Q000502:physiology*; D014644:Genetic Variation; D012641:Selection, Genetic