BRANTA — Charlotte Récapet
Melanin-based coloration as a signal of alternative life-history strategies in feral pigeon Columba livia
Institution:Ecole Normale Supérieure, Paris, France
Supervisors: Julien Gasparini, Lisa Jacquin
Details: MSc 2011 (Completed)
Address: UMR CNRS 5558 Biométrie et Biologie Évolutive, Université Claude Bernard Lyon 1, 43 Bd du 11 Novembre 1918, Bat Gregor Mendel, F-69622 Villeurbanne Cedex, France or Département Écologie & Évolution, Groupe du Dr Pierre Bize, UNIL, Biophore, CH-1015 Lausanne, Switzerland (Mar 2013) Email
Subject Keywords: coloration, color polymorphism, feral pigeon, food restriction, life-history strategies, melanin
Species Keywords: Feral pigeon, Columba livia
Fluctuations of environmental conditions and selective pressures over time or space have been hypothesized to drive genetic diversification and genetic diversity maintenance in natural populations. However, empirical evidences of this disruptive selection are still rare. Genetic-based variation in melanin-based coloration is widespread among animals and is related to variation in physiological and life-history traits. Differently coloured individuals may thus differ in the resolution of physiological and life-history trade-offs, which open the interesting possibility that melanin-based coloration could be a signal of genetic strategies facing variable environments. Therefore it constitutes a good trait to study selective pressures potentially responsible for genetic polymorphism maintenance.
In this study, we aimed at comparing life-history traits of differently coloured individuals under various parasitic pressures and food availability conditions. We wanted to determine whether melanin-based coloration was linked to different resolutions of trade-offs between maintenance, immunity and reproduction. We submitted differently coloured captive feral pigeons to different food conditions and immune challenges and measured their investment in body mass maintenance, egg laying, and offspring quality.
We found evidences of trade-offs between reproduction and maintenance, as well as between reproduction and immunity. These relationships were similar between experimental conditions and between colorations, suggesting that they are physiologically constrained. However, differently coloured individuals seemed to adjust their life-history traits to experimental conditions in different ways. Darker individuals maintained a higher reproductive output whatever the food limitation and immune challenge, with a negative impact on body mass. On the contrary, lighter individuals seemed to adapt their reproductive output to environmental conditions, and showed lower body mass losses in harsh food conditions. Differently coloured individuals may thus display alternative reaction norms to different environmental conditions.
Jacquin L., Récapet C., Bouche P., Leboucher G. and Gasparini J. (2012). Melanin-based coloration reflects alternative strategies to cope with food limitation in pigeons. Behavioral Ecology 23, 907-915.