Correlated evolution of mating behaviour and morphology in large carpenter bees (Xylocopa)Remko Leys1, 2 and Katja Hogendoorn3
1 Evolutionary Biology Unit South, Australian Museum, North Terrace SA 5000, Adelaide, Australia
2 School of Earth and Environmental Sciences, University of Adelaide, Australia
3 School of Agriculture, Food and Wine, The University of Adelaide, Adelaide SA 5005, Australia
(Received 12 June 2007 - Revised 25 September 2007 - Accepted 3 October 2007 - Published online 2 February 2008)
Abstract - Carpenter bees (Xylocopa) display variation in mating strategies. In several subgenera males defend territories that contain resources for females. In other subgenera males defend a small non-resource territory. Here, we investigate the correlation between three morphological traits and mating strategy. We found associations between mating strategy and male eye size, size of the mesosomal gland and sexual colour dimorphism, as well as correlative evolution between the morphological characters. Analysis of the evolutionary pathways shows that resource defence, small glands and monomorphic sexes are ancestral states. Increases in gland size seem to precede or coincide with changes in mating behaviour, but changes towards sexual dimorphism follow changes in mating behaviour. Once a non-resource defence strategy with correlated morphology has evolved there are no reversals to the ancestral states. We discuss the types of selection that may have caused these correlative changes.
Key words: correlated evolution / molecular phylogeny / mating / sexual selection / Xylocopa
© INRA, DIB-AGIB, EDP Sciences 2008