title: Effects of allometry, productivity and lifestyle on rates and limits of body size evolution.
abstract: Body size affects nearly all aspects of organismal biology, so it is important to understand the constraints and dynamics of body size evolution. Despite empirical work on the macroevolution and macroecology of minimum and maximum size, there is little general quantitative theory on rates and limits of body size evolution. We present a general theory that integrates individual productivity, the lifestyle component of the slow-fast life-history continuum, and the allometric scaling of generation time to predict a clade's evolutionary rate and asymptotic maximum body size, and the shape of macroevolutionary trajectories during diversifying phases of size evolution. We evaluate this theory using data on the evolution of clade maximum body sizes in mammals during the Cenozoic. As predicted, clade evolutionary rates and asymptotic maximum sizes are larger in more productive clades (e.g. baleen whales), which represent the fast end of the slow-fast lifestyle continuum, and smaller in less productive clades (e.g. primates). The allometric scaling exponent for generation time fundamentally alters the shape of evolutionary trajectories, so allometric effects should be accounted for in models of phenotypic evolution and interpretations of macroevolutionary body size patterns. This work highlights the intimate interplay between the macroecological and macroevolutionary dynamics underlying the generation and maintenance of morphological diversity.
authors.affiliation: School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA. jordan.okie@asu.edu
authors.forename: Jordan G
authors.initials: JG
authors.lastname: Okie
authors.forename: Alison G
authors.initials: AG
authors.lastname: Boyer
authors.forename: James H
authors.initials: JH
authors.lastname: Brown
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Costa
authors.forename: S K Morgan
authors.initials: SK
authors.lastname: Ernest
authors.forename: Alistair R
authors.initials: AR
authors.lastname: Evans
authors.forename: Mikael
authors.initials: M
authors.lastname: Fortelius
authors.forename: John L
authors.initials: JL
authors.lastname: Gittleman
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Hamilton
authors.forename: Larisa E
authors.initials: LE
authors.lastname: Harding
authors.forename: Kari
authors.initials: K
authors.lastname: Lintulaakso
authors.forename: S Kathleen
authors.initials: SK
authors.lastname: Lyons
authors.forename: Juha J
authors.initials: JJ
authors.lastname: Saarinen
authors.forename: Felisa A
authors.initials: FA
authors.lastname: Smith
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Stephens
authors.forename: Jessica
authors.initials: J
authors.lastname: Theodor
authors.forename: Mark D
authors.initials: MD
authors.lastname: Uhen
authors.forename: Richard M
authors.initials: RM
authors.lastname: Sibly
mesh_terms: D000818:Animals; D005075:Biological Evolution; D049628:Body Size; D008322:Mammals; D008954:Models, Biological; D008962:Models, Theoretical; D011323:Primates; D014907:Whales
keywords: evolutionary rate; macroecology; mammal macroevolution; maximum body size; metabolic theory of ecology; slow–fast life-history continuum