title: Coupled dynamics of body mass and population growth in response to environmental change.
abstract: Environmental change has altered the phenology, morphological traits and population dynamics of many species. However, the links underlying these joint responses remain largely unknown owing to a paucity of long-term data and the lack of an appropriate analytical framework. Here we investigate the link between phenotypic and demographic responses to environmental change using a new methodology and a long-term (1976-2008) data set from a hibernating mammal (the yellow-bellied marmot) inhabiting a dynamic subalpine habitat. We demonstrate how earlier emergence from hibernation and earlier weaning of young has led to a longer growing season and larger body masses before hibernation. The resulting shift in both the phenotype and the relationship between phenotype and fitness components led to a decline in adult mortality, which in turn triggered an abrupt increase in population size in recent years. Direct and trait-mediated effects of environmental change made comparable contributions to the observed marked increase in population growth. Our results help explain how a shift in phenology can cause simultaneous phenotypic and demographic changes, and highlight the need for a theory integrating ecological and evolutionary dynamics in stochastic environments.
authors.affiliation: Department of Life Sciences, Imperial College London, Ascot, Berkshire SL5 7PY, UK. a.ozgul@imperial.ac.uk
authors.forename: Arpat
authors.initials: A
authors.lastname: Ozgul
authors.forename: Dylan Z
authors.initials: DZ
authors.lastname: Childs
authors.forename: Madan K
authors.initials: MK
authors.lastname: Oli
authors.forename: Kenneth B
authors.initials: KB
authors.lastname: Armitage
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Blumstein
authors.forename: Lucretia E
authors.initials: LE
authors.lastname: Olson
authors.forename: Shripad
authors.initials: S
authors.lastname: Tuljapurkar
authors.forename: Tim
authors.initials: T
authors.lastname: Coulson
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001835:Body Weight / Q000502:physiology*; D003120:Colorado; D005260:Female; D057232:Global Warming; D006605:Hibernation / Q000502:physiology*; D008392:Marmota / Q000033:anatomy & histology* / Q000254:growth & development / Q000502:physiology*; D010641:Phenotype; D011157:Population Dynamics; D012098:Reproduction / Q000502:physiology; D015996:Survival Rate; D013997:Time Factors; D014886:Weaning