title: Genetic constraints predict evolutionary divergence in Dalechampia blossoms.
abstract: If genetic constraints are important, then rates and direction of evolution should be related to trait evolvability. Here we use recently developed measures of evolvability to test the genetic constraint hypothesis with quantitative genetic data on floral morphology from the Neotropical vine Dalechampia scandens (Euphorbiaceae). These measures were compared against rates of evolution and patterns of divergence among 24 populations in two species in the D. scandens species complex. We found clear evidence for genetic constraints, particularly among traits that were tightly phenotypically integrated. This relationship between evolvability and evolutionary divergence is puzzling, because the estimated evolvabilities seem too large to constitute real constraints. We suggest that this paradox can be explained by a combination of weak stabilizing selection around moving adaptive optima and small realized evolvabilities relative to the observed additive genetic variance.
authors.affiliation: Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, 7491 Trondheim, Norway geir.h.bolstad@ntnu.no.
authors.forename: Geir H
authors.initials: GH
authors.lastname: Bolstad
authors.affiliation: Department of Biology, Centre for Ecological and Evolutionary Synthesis, University of Oslo, 0316 Oslo, Norway.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Hansen
authors.affiliation: Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, 7491 Trondheim, Norway.
authors.forename: Christophe
authors.initials: C
authors.lastname: Pélabon
authors.affiliation: Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway School of Biology and Center of Excellence in Phylogeny of Living Organisms, University of Tehran, 14155-6455 Tehran, Iran.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Falahati-Anbaran
authors.affiliation: School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK.
authors.forename: Rocío
authors.initials: R
authors.lastname: Pérez-Barrales
authors.affiliation: Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK Institute of Arctic Biology, University of Alaska, Fairbanks AK 99775, USA.
authors.forename: W Scott
authors.initials: WS
authors.lastname: Armbruster
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics*; D001499:Bayes Theorem; D005075:Biological Evolution; D003198:Computer Simulation; D019665:Euphorbiaceae / Q000033:anatomy & histology / Q000235:genetics*; D035264:Flowers / Q000033:anatomy & histology*; D005828:Genetics, Population; D008800:Mexico; D008954:Models, Biological; D010641:Phenotype; D010802:Phylogeny; D012641:Selection, Genetic; D013045:Species Specificity; D049490:Systems Biology
keywords: G-matrix; evolutionary rate; integration; macroevolution; microevolution; power relationship