title: Linking macrotrends and microrates: Re-evaluating microevolutionary support for Cope's rule.
abstract: Cope's rule, wherein a lineage increases in body size through time, was originally motivated by macroevolutionary patterns observed in the fossil record. More recently, some authors have argued that evidence exists for generally positive selection on individual body size in contemporary populations, providing a microevolutionary mechanism for Cope's rule. If larger body size confers individual fitness advantages as the selection estimates suggest, thereby explaining Cope's rule, then body size should increase over microevolutionary time scales. We test this corollary by assembling a large database of studies reporting changes in phenotypic body size through time in contemporary populations, as well as studies reporting average breeding values for body size through time. Trends in body size were quite variable with an absence of any general trend, and many populations trended toward smaller body sizes. Although selection estimates can be interpreted to support Cope's rule, our results suggest that actual rates of phenotypic change for body size cannot. We discuss potential reasons for this discrepancy and its implications for the understanding of Cope's rule.
authors: Redpath Museum and Department of Biology, McGill University, Montreal, Quebec, H3A 0C4, Canada. kiyoko.gotanda@mail.mcgill.ca.
authors: Kiyoko M
authors: KM
authors: Gotanda
authors: Facultad de Ciencias Forestales y Recursos Naturales, Instituto de Conservación Biodiversidad y Territorio, Universidad Austral de Chile, Valdivia.|Facultad de Ciencias, Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia.
authors: Cristián
authors: C
authors: Correa
authors: Institute of Integrative Biology, ETH Zürich, Universitätstrasse 16, Zürich, 8092, Switzerland.
authors: Martin M
authors: MM
authors: Turcotte
authors: Redpath Museum and Department of Biology, McGill University, Montreal, Quebec, H3A 0C4, Canada.
authors: Gregor
authors: G
authors: Rolshausen
authors: Redpath Museum and Department of Biology, McGill University, Montreal, Quebec, H3A 0C4, Canada.
authors: Andrew P
authors: AP
authors: Hendry
mesh_terms: D049628:Body Size / Q000235:genetics*; D019143:Evolution, Molecular; D056084:Genetic Fitness; D006801:Humans; D008957:Models, Genetic; D010641:Phenotype; D011153:Population / Q000235:genetics*; D012641:Selection, Genetic
keywords: Body size; Darwins; Haldanes; breeding values; contemporary evolution; rates of evolution