rsos.royalsocietypublishing.org Research Cite this article: Lopez-Osorio F, Perrard A, Pickett KM, Carpenter JM, Agnarsson I. 2015 Phylogenetic tests reject Emery’s rule in the evolution of social parasitism in yellowjackets and hornets (Hymenoptera: Vespidae, Vespinae). R. Soc. open sci. 2: 150159. http://dx.doi.org/10.1098/rsos.150159 Received: 21 April 2015 Accepted: 3 August 2015 Subject Category: Biology (whole organism) Subject Areas: evolution/taxonomy and systematics/behaviour Keywords: social parasitism, Emery’s rule, social insects, phylogeny, Vespinae Author for correspondence: Federico Lopez-Osorio e-mail: lopezos@uvm.edu † Deceased 11 February 2011. Electronic supplementary material is available at http://dx.doi.org/10.1098/rsos.150159 or via http://rsos.royalsocietypublishing.org. Phylogenetic tests reject Emery’s rule in the evolution of social parasitism in yellowjackets and hornets (Hymenoptera: Vespidae, Vespinae) Federico Lopez-Osorio 1 , Adrien Perrard 2 , Kurt M. Pickett 1,† , James M. Carpenter 2 and Ingi Agnarsson 1,3 1 Department of Biology, University of Vermont, Room 120A Marsh Life Science Building, 109 Carrigan Drive, Burlington, VT 05405, USA 2 Division of Invertebrate Zoology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10023, USA 3 Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20004, USA Social parasites exploit the brood-care behaviour and social structure of one or more host species. Within the social Hymenoptera there are different types of social parasitism. In its extreme form, species of obligate social parasites, or inquilines, do not have the worker caste and depend entirely on the workers of a host species to raise their reproductive offspring. The strict form of Emery’s rule states that social parasites share immediate common ancestry with their hosts. Moreover, this rule has been linked with a sympatric origin of inquilines from their hosts. Here, we conduct phylogenetic analyses of yellowjackets and hornets based on 12 gene fragments and evaluate competing evolutionary scenarios to test Emery’s rule. We find that inquilines, as well as facultative social parasites, are not the closest relatives of their hosts. Therefore, Emery’s rule in its strict sense is rejected, suggesting that social parasites have not evolved sympatrically from their hosts in yellowjackets and hornets. However, the relaxed version of the rule is supported, as inquilines and their hosts belong to the same Dolichovespula clade. Furthermore, inquilinism has evolved only once in Dolichovespula. 2015 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. on September 3, 2015 http://rsos.royalsocietypublishing.org/ Downloaded from