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Influence of female moulting status on pairing decisions and size-assortative mating in amphipods

Authors

  • S. Cornet,

    Corresponding author
    1. Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR CNRS 5175, Montpellier, France
    • Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), UMR CNRS 5290-IRD 224-UM1-UM2, Montpellier, France
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  • G. Luquet,

    1. Biogéosciences, Equipe Biome, UMR CNRS 5561, Université de Bourgogne, Dijon, France
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  • L. Bollache

    1. Biogéosciences, Equipe Biome, UMR CNRS 5561, Université de Bourgogne, Dijon, France
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Correspondence

Stéphane Cornet, MIVEGEC, Institut de Recherche pour le Développement, 911 Av. Agropolis, 34394 Montpellier, France. Tel: +33 4 6741 6373; Fax: +33 4 6741 6299

Email: stephane.cornet@ird.fr

Abstract

Precopulatory mate guarding is a common strategy, which has evolved in species where the female receptivity (and thus egg fertilization) is predictable, but also limited to a short period. Although males are larger than females in many amphipods, the largest males pair with the largest females, leading to a positive size-assortative pairing. Size-assortative pairing has received much attention but how moulting physiology could affect pairing decisions has rarely been studied. Here, we tested the hypothesis that the size-assortative pairing in the freshwater amphipod Gammarus pulex is closely related to the female moult cycle. We characterized moulting status by observing the new cuticle formation then tested the influence of the moulting status on pairing decision. Overall, female moult stage influences the variation and intensity of size-assortative pairing. Whereas individuals tended to pair at random as soon as the females become receptive (early beginning of the premoult stage), size-assortative pairing was stronger as females were closer to the moult. Thus, moulting and pairing decision could not be dissociated and moulting should be controlled for when examining the behavioural ecology of mate choice decisions in crustaceans.

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