title: Extensive range overlap between heliconiine sister species: evidence for sympatric speciation in butterflies?
abstract: BACKGROUND
  Sympatric speciation is today generally viewed as plausible, and some well-supported examples exist, but its relative contribution to biodiversity remains to be established. We here quantify geographic overlap of sister species of heliconiine butterflies, and use age-range correlations and spatial simulations of the geography of speciation to infer the frequency of sympatric speciation. We also test whether shifts in mimetic wing colour pattern, host plant use and climate niche play a role in speciation, and whether such shifts are associated with sympatry.
  
  
  RESULTS
  Approximately a third of all heliconiine sister species pairs exhibit near complete range overlap, and analyses of the observed patterns of range overlap suggest that sympatric speciation contributes 32%-95% of speciation events. Müllerian mimicry colour patterns and host plant choice are highly labile traits that seem to be associated with speciation, but we find no association between shifts in these traits and range overlap. In contrast, climatic niches of sister species are more conserved.
  
  
  CONCLUSIONS
  Unlike birds and mammals, sister species of heliconiines are often sympatric and our inferences using the most recent comparative methods suggest that sympatric speciation is common. However, if sister species spread rapidly into sympatry (e.g. due to their similar climatic niches), then assumptions underlying our methods would be violated. Furthermore, although we find some evidence for the role of ecology in speciation, ecological shifts did not show the associations with range overlap expected under sympatric speciation. We delimit species of heliconiines in three different ways, based on "strict and " "relaxed" biological species concepts (BSC), as well as on a surrogate for the widely-used "diagnostic" version of the phylogenetic species concept (PSC). We show that one reason why more sympatric speciation is inferred in heliconiines than in birds may be due to a different culture of species delimitation in the two groups. To establish whether heliconiines are exceptional will require biogeographic comparative studies for a wider range of animal taxa including many more invertebrates.
authors.affiliation: Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK. neil.rosser@york.ac.uk.|Present address: Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK. neil.rosser@york.ac.uk.
authors.forename: Neil
authors.initials: N
authors.lastname: Rosser
authors.affiliation: Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK. kk443@cam.ac.uk.
authors.forename: Krzysztof M
authors.initials: KM
authors.lastname: Kozak
authors.affiliation: Division of Biology, Imperial College at Silwood Park, Ascot, SL5 7PY, UK. albert.phillimore@ed.ac.uk.|Present address: Institute of Evolutionary Biology, University of Edinburgh, Ashworth Laboratories, Kings Buildings, West Mains Road, Edinburgh, EH9 3JT, UK. albert.phillimore@ed.ac.uk.
authors.forename: Albert B
authors.initials: AB
authors.lastname: Phillimore
authors.affiliation: Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK. jmallet@oeb.harvard.edu.|Present address: Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA, 02138, USA. jmallet@oeb.harvard.edu.
authors.forename: James
authors.initials: J
authors.lastname: Mallet
mesh_terms: D000818:Animals; D044822:Biodiversity; D002080:Butterflies / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics*; D002980:Climate; D003198:Computer Simulation; D016208:Databases, Factual; D004463:Ecology; D049810:Genetic Speciation; D010802:Phylogeny; D061350:Sympatry; D014921:Wings, Animal / Q000033:anatomy & histology