TY  - THES
AU  - Quentin Schull
PY  - 2016//
TI  - Sexual selection, social selection and individual quality: underlying mechanisms and ultimate consequences of ornamentation in a monomorphic species, the King penguin (Aptenodytes patagonicus)
N2  - <br />Darwin&rsquo;s seminal theory of evolution by means of natural selection, first published 157 years ago, has been in constant refinement ever since. Specifically, evolutionary biologists have been fascinated by the existence of animal armaments and ornaments, as at first glance, such morphological features might appear detrimental to individual survival and reproduction, and thus in contradiction with Darwin&rsquo;s original idea. However, as already pointed out by Darwin in 1871, handicapping traits in several species might evolve if they provide benefits in the acquisition of mating partners. The<br />production and maintenance of extravagant ornaments was more widely suggested to evolve by conspecific preference providing information on individual intrinsic quality in sexual contexts (sexual selection) or on individual social quality in non-reproductive contexts (social selection). Under those respective frameworks, several hypotheses have been proposed and empirical support has been provided for most. The king penguin (Aptenodytes patagonicus) is an outstanding model allowing to investigate several of those hypotheses simultaneously. The king penguin is a monomorphic bird species, for which both males and females display similar colourful ornaments, both on the plumage and the beak. Plumage ornament coloration is produced by i) endogenous pigments, whereas beak ornament coloration is produced by both ii) exogenous pigments and iii) structural cellular features. Throughout this thesis, I identified the costs associated with the production and maintenance of those ornamental features highlighting their honest character in signalling the quality of their bearer. My results show that those ornaments are partly condition-dependent, and reliable traits that may be used to assess the quality of a potential sexual partner in both sexes, implying that their evolution and maintenance is partly determined by mutual mate choice and sexual selection. On the other hand, some traits remained condition-independent in their production, suggesting that the cost associated with their expression was deferred over time and the evolution of those ornaments likely shaped by non-sexual social selection. This research work aimed at improving our comprehension of the mechanisms implicated in the evolution of extravagant traits and the ultimate fitness benefits of such traits, questions that have stirred the curiosity of evolutionary biologists for decades. In the process, it has empirically shed first lights on the fundamental energy mechanism likely underlying the evolution of animal ornamentation.<br />Keywords: social selection, sexual selection, evolution, honest signal, monomorphic species, king penguins
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ID  - QuentinSchull2016
ER  -