Status-signalling chemical badges in male Iberian rock lizards

Authors

  • J. MARTÍN,

    Corresponding author
    1. Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales (MNCN), CSIC, José Gutiérrez Abascal 2, 28006 Madrid, Spain, and
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  • P. L. MOREIRA,

    1. Centro de Biologia Ambiental, Faculdade de Ciências da Universidade de Lisboa, Edifício C-2 Campo Grande, 1749-016 Lisboa, Portugal
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  • P. LÓPEZ

    1. Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales (MNCN), CSIC, José Gutiérrez Abascal 2, 28006 Madrid, Spain, and
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†Author to whom correspondence should be addressed. E-mail: Jose.Martin@mncn.csic.es

Summary

  • 1Male competition for females often results in the evolution of conspicuous male traits that signal fighting ability or dominance status. Most studies examining mechanisms allowing these traits to function as reliable status signals (or badges) have focused on conspicuous visual or acoustic traits. However, many animals communicate chemically, and chemical traits alone may also signal male dominance status.
  • 2We examined whether chemicals in femoral gland secretions of male Iberian rock lizards (Lacerta monticola monticola Boulenger 1905) may signal dominance status.
  • 3In staged encounters, larger males were dominant over smaller ones. While controlling for male body size, males of higher dominance status produced femoral secretions with higher proportions of hexadecanol and octadecanol.
  • 4Tongue-flick assays showed that males were able to (1) discriminate, by chemosensory cues alone, the different concentrations of hexadecanol from other chemicals presented in femoral secretions; (2) respond aggressively towards hexadecanol while responding neutrally towards other chemicals; and (3) show differential chemosensory and aggressive behaviours towards hexadecanol according to their own dominance status.
  • 5These results suggest that hexadecanol may be a reliable status badge. Moreover, because hexadecanol elicits male aggressive behaviour, subordinate males signalling high status (‘cheaters’) may end up paying high fighting costs. In addition, males that had higher dominance status, and that allocated higher proportions of hexadecanol to femoral secretions, had greater T-cell immune responses. This result suggests a possible link between quality of the immune system, dominance status, and chemical signals.

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