title: Reduction of female copulatory damage by resilin represents evidence for tolerance in sexual conflict.
abstract: Intergenomic evolutionary conflicts increase biological diversity. In sexual conflict, female defence against males is generally assumed to be resistance, which, however, often leads to trait exaggeration but not diversification. Here, we address whether tolerance, a female defence mechanism known from interspecific conflicts, exists in sexual conflict. We examined the traumatic insemination of female bed bugs via cuticle penetration by males, a textbook example of sexual conflict. Confocal laser scanning microscopy revealed large proportions of the soft and elastic protein resilin in the cuticle of the spermalege, the female defence organ. Reduced tissue damage and haemolymph loss were identified as adaptive female benefits from resilin. These did not arise from resistance because microindentation showed that the penetration force necessary to breach the cuticle was significantly lower at the resilin-rich spermalege than at other cuticle sites. Furthermore, a male survival analysis indicated that the spermalege did not impose antagonistic selection on males. Our findings suggest that the specific spermalege material composition evolved to tolerate the traumatic cuticle penetration. They demonstrate the importance of tolerance in sexual conflict and genitalia evolution, extend fundamental coevolution and speciation models and contribute to explaining the evolution of complexity. We propose that tolerance can drive trait diversity.
authors: Department of Functional Morphology and Biomechanics, Institute of Zoology, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany Biological Oceanography, GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany jmichels@zoologie.uni-kiel.de.
authors: Jan
authors: J
authors: Michels
authors: Department of Functional Morphology and Biomechanics, Institute of Zoology, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany.
authors: Stanislav N
authors: SN
authors: Gorb
authors: Applied Zoology, Department of Biology, Technische Universität Dresden, Helmholtzstraße 10, 01217 Dresden, Germany Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK klaus.reinhardt@tu-dresden.de.
authors: Klaus
authors: K
authors: Reinhardt
mesh_terms: D000818:Animals; D001511:Bedbugs / Q000502:physiology*; D005075:Biological Evolution; D003163:Competitive Behavior; D004548:Elasticity; D005260:Female; D014644:Genetic Variation; D006458:Hemolymph; D019476:Insect Proteins / Q000502:physiology*; D008297:Male; D008853:Microscopy; D018613:Microscopy, Confocal; D012641:Selection, Genetic; D012726:Sexual Behavior, Animal; D013314:Stress, Mechanical; D014466:Ultraviolet Rays
chemical_list: D019476:Insect Proteins; C030951:resilin
keywords: antagonistic coevolution; bed bug; resilin; sexual conflict; tolerance; traumatic insemination