title: Environmental and scale-dependent evolutionary trends in the body size of crustaceans.
abstract: The ecological and physiological significance of body size is well recognized. However, key macroevolutionary questions regarding the dependency of body size trends on the taxonomic scale of analysis and the role of environment in controlling long-term evolution of body size are largely unknown. Here, we evaluate these issues for decapod crustaceans, a group that diversified in the Mesozoic. A compilation of body size data for 792 brachyuran crab and lobster species reveals that their maximum, mean and median body size increased, but no increase in minimum size was observed. This increase is not expressed within lineages, but is rather a product of the appearance and/or diversification of new clades of larger, primarily burrowing to shelter-seeking decapods. This argues against directional selective pressures within lineages. Rather, the trend is a macroevolutionary consequence of species sorting: preferential origination of new decapod clades with intrinsically larger body sizes. Furthermore, body size evolution appears to have been habitat-controlled. In the Cretaceous, reef-associated crabs became markedly smaller than those in other habitats, a pattern that persists today. The long-term increase in body size of crabs and lobsters, coupled with their increased diversity and abundance, suggests that their ecological impact may have increased over evolutionary time.
authors.affiliation: Florida Museum of Natural History, University of Florida, 1659 Museum Road, PO Box 117800, Gainesville, FL 32611, USA adielklompmaker@gmail.com.
authors.forename: Adiël A
authors.initials: AA
authors.lastname: Klompmaker
authors.affiliation: Department of Geology, Kent State University at Stark, 6000 Frank Avenue NW, North Canton, OH 44720, USA.
authors.forename: Carrie E
authors.initials: CE
authors.lastname: Schweitzer
authors.affiliation: Department of Geology, Kent State University, Kent, OH 44242, USA.
authors.forename: Rodney M
authors.initials: RM
authors.lastname: Feldmann
authors.affiliation: Florida Museum of Natural History, University of Florida, 1659 Museum Road, PO Box 117800, Gainesville, FL 32611, USA.
authors.forename: Michał
authors.initials: M
authors.lastname: Kowalewski
mesh_terms: D000818:Animals; D005075:Biological Evolution; D049628:Body Size; D033364:Decapoda / Q000502:physiology*; D004777:Environment; D005580:Fossils / Q000033:anatomy & histology; D010802:Phylogeny
keywords: Crustacea; Decapoda; Mesozoic; body size; environment; habitat