title: The macroevolutionary consequences of phenotypic integration: from development to deep time.
abstract: Phenotypic integration is a pervasive characteristic of organisms. Numerous analyses have demonstrated that patterns of phenotypic integration are conserved across large clades, but that significant variation also exists. For example, heterochronic shifts related to different mammalian reproductive strategies are reflected in postcranial skeletal integration and in coordination of bone ossification. Phenotypic integration and modularity have been hypothesized to shape morphological evolution, and we extended simulations to confirm that trait integration can influence both the trajectory and magnitude of response to selection. We further demonstrate that phenotypic integration can produce both more and less disparate organisms than would be expected under random walk models by repartitioning variance in preferred directions. This effect can also be expected to favour homoplasy and convergent evolution. New empirical analyses of the carnivoran cranium show that rates of evolution, in contrast, are not strongly influenced by phenotypic integration and show little relationship to morphological disparity, suggesting that phenotypic integration may shape the direction of evolutionary change, but not necessarily the speed of it. Nonetheless, phenotypic integration is problematic for morphological clocks and should be incorporated more widely into models that seek to accurately reconstruct both trait and organismal evolution.
authors.affiliation: Research Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK a.goswami@ucl.ac.uk.
authors.forename: A
authors.initials: A
authors.lastname: Goswami
authors.affiliation: Research Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK Department of Anthropology, University College London, 14 Taviton Street, London WC1H 0BW, UK Department of Anthropology, Stony Brook University, Circle Road, Stony Brook, NY 11794, USA.
authors.forename: J B
authors.initials: JB
authors.lastname: Smaers
authors.affiliation: Department of Anthropology, University College London, 14 Taviton Street, London WC1H 0BW, UK.
authors.forename: C
authors.initials: C
authors.lastname: Soligo
authors.affiliation: Department of Geological Sciences, Indiana University, 1001 East 10th Street, Bloomington, IN 47401, USA.
authors.forename: P D
authors.initials: PD
authors.lastname: Polly
mesh_terms: D000818:Animals; D044822:Biodiversity; D005075:Biological Evolution; D019521:Body Patterning / Q000502:physiology; D015509:Developmental Biology; D008954:Models, Biological; D010641:Phenotype; D010802:Phylogeny; D012641:Selection, Genetic; D049490:Systems Biology; D013997:Time Factors; D014714:Vertebrates / Q000033:anatomy & histology*
keywords: Mammalia; disparity; evolutionary rates; modularity; ontogeny