title: The dynamics of phenotypic change and the shrinking sheep of St. Kilda.
abstract: Environmental change, including climate change, can cause rapid phenotypic change via both ecological and evolutionary processes. Because ecological and evolutionary dynamics are intimately linked, a major challenge is to identify their relative roles. We exactly decomposed the change in mean body weight in a free-living population of Soay sheep into all the processes that contribute to change. Ecological processes contribute most, with selection--the underpinning of adaptive evolution--explaining little of the observed phenotypic trend. Our results enable us to explain why selection has so little effect even though weight is heritable, and why environmental change has caused a decline in the body size of Soay sheep.
authors: Department of Life Sciences, Imperial College London, Silwood Park, Ascot, Berkshire SL5 7PY, UK.
authors: Arpat
authors: A
authors: Ozgul
authors: Shripad
authors: S
authors: Tuljapurkar
authors: Tim G
authors: TG
authors: Benton
authors: Josephine M
authors: JM
authors: Pemberton
authors: Tim H
authors: TH
authors: Clutton-Brock
authors: Tim
authors: T
authors: Coulson
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D005075:Biological Evolution; D049628:Body Size; D001835:Body Weight; D017753:Ecosystem; D004777:Environment; D005260:Female; D008297:Male; D008954:Models, Biological; D010641:Phenotype; D034561:Sheep, Domestic / Q000033:anatomy & histology* / Q000254:growth & development