Pheromone production, male abundance, body size, and the evolution of elaborate antennae in moths Matthew R. E. Symonds1,2, Tamara L. Johnson1 & Mark A. Elgar1 1Department of Zoology, University of Melbourne, Victoria 3010, Australia 2Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood, Victoria 3125, Australia. Keywords Abstract Antennal morphology, forewing length, Lepidoptera, phylogenetic generalized least The males of some species of moths possess elaborate feathery antennae. It is widely squares, sex pheromone. assumed that these striking morphological features have evolved through selection for males with greater sensitivity to the female sex pheromone, which is typically Correspondence released in minute quantities. Accordingly, females of species in which males have Matthew R. E. Symonds, School of Life and elaborate (i.e., pectinate, bipectinate, or quadripectinate) antennae should produce Environmental Sciences, Deakin University, 221 the smallest quantities of pheromone. Alternatively, antennal morphology may Burwood Highway, Burwood, Victoria 3125, Australia. Tel: +61 3 9251 7437; Fax: +61 3 be associated with the chemical properties of the pheromone components, with 9251 7626; E-mail: elaborate antennae being associated with pheromones that diffuse more quickly (i.e.,
[email protected] have lower molecular weights). Finally, antennal morphology may reflect population structure, with low population abundance selecting for higher sensitivity and hence Funded by a Discovery Project grant from the more elaborate antennae. We conducted a phylogenetic comparative analysis to test Australian Research Council (DP0987360). these explanations using pheromone chemical data and trapping data for 152 moth species. Elaborate antennae are associated with larger body size (longer forewing Received: 13 September 2011; Revised: 23 length), which suggests a biological cost that smaller moth species cannot bear.