title: Experimental evidence that the Ornstein-Uhlenbeck model best describes the evolution of leaf litter decomposability.
abstract: Leaf litter decomposability is an important effect trait for ecosystem functioning. However, it is unknown how this effect trait evolved through plant history as a leaf 'afterlife' integrator of the evolution of multiple underlying traits upon which adaptive selection must have acted. Did decomposability evolve in a Brownian fashion without any constraints? Was evolution rapid at first and then slowed? Or was there an underlying mean-reverting process that makes the evolution of extreme trait values unlikely? Here, we test the hypothesis that the evolution of decomposability has undergone certain mean-reverting forces due to strong constraints and trade-offs in the leaf traits that have afterlife effects on litter quality to decomposers. In order to test this, we examined the leaf litter decomposability and seven key leaf traits of 48 tree species in the temperate area of China and fitted them to three evolutionary models: Brownian motion model (BM), Early burst model (EB), and Ornstein-Uhlenbeck model (OU). The OU model, which does not allow unlimited trait divergence through time, was the best fit model for leaf litter decomposability and all seven leaf traits. These results support the hypothesis that neither decomposability nor the underlying traits has been able to diverge toward progressively extreme values through evolutionary time. These results have reinforced our understanding of the relationships between leaf litter decomposability and leaf traits in an evolutionary perspective and may be a helpful step toward reconstructing deep-time carbon cycling based on taxonomic composition with more confidence.
authors.affiliation: Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, College of Life and Environmental Sciences, Hangzhou Normal University Hangzhou, China ; State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences Beijing, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Pan
authors.affiliation: Department of Ecological Science, VU University Amsterdam, the Netherlands.
authors.forename: Johannes H C
authors.initials: JH
authors.lastname: Cornelissen
authors.affiliation: Department of Ecological Science, VU University Amsterdam, the Netherlands.
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences Beijing, China.
authors.forename: Guo-Fang
authors.initials: GF
authors.lastname: Liu
authors.affiliation: Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, College of Life and Environmental Sciences, Hangzhou Normal University Hangzhou, China ; State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences Beijing, China.
authors.forename: Yu-Kun
authors.initials: YK
authors.lastname: Hu
authors.affiliation: Université de Rennes 1, Centre National de la Recherche Scientifique Campus de Beaulieu Bâtiment 14 A, 35042, Rennes, France.
authors.forename: Andreas
authors.initials: A
authors.lastname: Prinzing
authors.affiliation: Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, College of Life and Environmental Sciences, Hangzhou Normal University Hangzhou, China ; State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences Beijing, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Dong
authors.affiliation: Department of Ecological Science, VU University Amsterdam, the Netherlands ; School of Biological, Earth and Environmental Sciences, University of New South Wales Sydney, NSW, Australia.
authors.forename: William K
authors.initials: WK
authors.lastname: Cornwell
keywords: Brownian motion model (BM); early burst model (EB); ecosystem function; effect trait; evolution; leaf litter decomposability; phylogenetic half-life