title: Comparative analyses of the influence of developmental mode on phenotypic diversification rates in shorebirds.
abstract: Phenotypic diversity is not evenly distributed across lineages. Here, we describe and apply a maximum-likelihood phylogenetic comparative method to test for different rates of phenotypic evolution between groups of the avian order Charadriiformes (shorebirds, gulls and alcids) to test the influence of a binary trait (offspring demand; semi-precocial or precocial) on rates of evolution of parental care, mating systems and secondary sexual traits. In semi-precocial species, chicks are reliant on the parents for feeding, but in precocial species the chicks feed themselves. Thus, where the parents are emancipated from feeding the young, we predict that there is an increased potential for brood desertion, and consequently for the divergence of mating systems. In addition, secondary sexual traits are predicted to evolve faster in groups with less demanding young. We found that precocial development not only allows rapid divergence of parental care and mating behaviours, but also promotes the rapid diversification of secondary sexual characters, most notably sexual size dimorphism (SSD) in body mass. Thus, less demanding offspring appear to facilitate rapid evolution of breeding systems and some sexually selected traits.
authors.affiliation: Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK. g.thomas@imperial.ac.uk
authors.forename: Gavin H
authors.initials: GH
authors.lastname: Thomas
authors.forename: Robert P
authors.initials: RP
authors.lastname: Freckleton
authors.forename: Tamás
authors.initials: T
authors.lastname: Székely
mesh_terms: D000818:Animals; D005075:Biological Evolution; D046091:Charadriiformes / Q000145:classification / Q000254:growth & development / Q000502:physiology*; D005247:Feeding Behavior; D006801:Humans; D008297:Male; D009425:Nesting Behavior; D010641:Phenotype; D010802:Phylogeny; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal