title: Colony size predicts division of labour in attine ants.
abstract: Division of labour is central to the ecological success of eusocial insects, yet the evolutionary factors driving increases in complexity in division of labour are little known. The size-complexity hypothesis proposes that, as larger colonies evolve, both non-reproductive and reproductive division of labour become more complex as workers and queens act to maximize inclusive fitness. Using a statistically robust phylogenetic comparative analysis of social and environmental traits of species within the ant tribe Attini, we show that colony size is positively related to both non-reproductive (worker size variation) and reproductive (queen-worker dimorphism) division of labour. The results also suggested that colony size acts on non-reproductive and reproductive division of labour in different ways. Environmental factors, including measures of variation in temperature and precipitation, had no significant effects on any division of labour measure or colony size. Overall, these results support the size-complexity hypothesis for the evolution of social complexity and division of labour in eusocial insects. Determining the evolutionary drivers of colony size may help contribute to our understanding of the evolution of social complexity.
authors.affiliation: School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, UK Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK h.ferguson-gow@ucl.ac.uk.
authors.forename: Henry
authors.identifier: http://orcid.org/0000-0002-7151-6421
authors.initials: H
authors.lastname: Ferguson-Gow
authors.affiliation: Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK.
authors.forename: Seirian
authors.initials: S
authors.lastname: Sumner
authors.affiliation: School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, UK.
authors.forename: Andrew F G
authors.initials: AF
authors.lastname: Bourke
authors.affiliation: Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK Centre for Biodiversity and Environment Research, Department of Genetics, Evolution and Environment, University College London, Gower St., London WC1E 6BT, UK kate.e.jones@ucl.ac.uk.
authors.forename: Kate E
authors.identifier: http://orcid.org/0000-0001-5231-3293
authors.initials: KE
authors.lastname: Jones
mesh_terms: D000818:Animals; D001000:Ants / Q000502:physiology*; D001070:Appetitive Behavior; D001522:Behavior, Animal; D005075:Biological Evolution; D010802:Phylogeny; D011156:Population Density; D012919:Social Behavior
keywords: Formicidae; caste evolution; queen–worker dimorphism; social evolution; worker size polymorphism