Behavioral Ecology Advance Access originally published online on October 12, 2009
Behavioral Ecology 2009 20(6):1289-1294; doi:10.1093/beheco/arp133
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Prevalence of avian influenza and sexual selection in ducks
a Behavioral Ecology Group, Department of Systematic Zoology and Ecology, Eötvös Loránd University, Pázmány Péter sétány 1/C, H-1117 Budapest, Hungary b Laboratoire d'Ecologie, Systématique et Evolution, Université Paris Sud, Bâtiment 362, 91405 Orsay Cedex, France c Center for Advanced Study, Drammensveien 78, NO-0271 Oslo, Norway d Department of Biology, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, B-2610 Wilrijk, Belgium e Department of Evolutionary Ecology, Estación Biológica de Doñana-CSIC, c/Americo Vespucio, s/n, 41092 Sevilla, Spain
Address correspondence to G. Hegyi. E-mail: everest{at}ludens.elte.hu.
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Abstract |
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Investigations of avian influenza have so far focused on the global circulation and conversion of virus strains and showed that wild waterfowl and especially ducks represent the reservoir and source of virus strains that can become highly pathogenic in domestic species. Information is largely missing regarding the routes of transmission between individuals and the species of concern for transmission. Moreover, evolutionary comparative studies only considered ecological factors and ignored other potential determinants of virus transmission. Such determinants include the mating strategies of hosts because links between sexual selection and parasites are well known. Here, we show that morphological adaptations associated with copulation frequency in both male and female hosts strongly explain differences in low-pathogenic influenza prevalence among wild duck species. Prevalence is negatively related to male phallus length and female vaginal complexity, traits that evolved due to sexual conflict over forced copulations. This pattern suggests a hitherto unrecognized transmission route of the virus via copulation and subsequent mother–offspring transfer. Due to a relationship between forced copulations and the expression of white wing covert patches, male covert patch expression and sexual dichromatism in covert patch expression are positively related to influenza prevalence. Our results suggest that the arms race between male and female reproductive tracts had epidemiological consequences. Our findings further suggest that morphological correlates of sexual selection in ducks, including conspicuous plumage ornamentation, could be robust clues to identify high-risk host species during the large-scale monitoring of avian influenza.
Key words: forced copulation, plumage ornament, reproductive anatomy, viral transmission, waterfowl.
Received 24 February 2009; revised 5 August 2009; accepted 1 September 2009.