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Soutiendra publiquement ses travaux de thèse intitulés :

Origins and functions of iridescence colours in hummingbirds

mercredi 18 décembre 2019 à 14h  

Amphithéâtre de la délégation

 

DEFENSE IN ENGLISH

Abstract:

The study of colour can offer valuable insights into the fine details of evolutive mechanisms. It is indeed a complex trait, which can evolve along several dimensions, and which is controlled by multiple selective pressures with often opposed effects. Yet, there is one class of colours that has received few attention from evolutionary biologists: iridescent colours. This is due to the inherent complexity of these colours and the fact that even their quantitative measurement is a challenge in itself. During my PhD, I worked with physicists and biologists and I used optical theory to propose a new measurement method for iridescent colours. I then validated this method empirically by showing that it produced reliable and repeatable estimates for both hummingbirds and Morpho butterflies. My work during these three years has also focused on the development of other methodological tools and software for the study of colours. I also focused more precisely on iridescent colours in hummingbirds. I mainly investigated two sides of this topic and tried to find out (i) the proximate causes of iridescence in hummingbirds: how do they produce the striking colours they are renowned for? (ii) the ultimate causes of iridescence: what are the evolutionary mechanisms which control the evolution of iridescence at the community level? I found out that the structures producing iridescence in hummingbirds are way more diverse than what we previously thought. They even display an usual type of structure which has not been described in any other group yet. I also showed that at the interspecific level, iridescent colours on the back of hummingbirds tend to be similar among species occupying the same communities, which suggests a possible role of the environment in the evolution of these colours, possibly for camouflage against predators.

Keywords:

Iridescence, structural colouration, hummingbirds, evolutionary biology, colour science

Membres du jury

Daniel Osorio                                   University of Sussex                                 Rapporteur

Andrew Parnell                                 University of Sheffield                              Rapporteur

Mathieu Joron                                  CEFE, CNRS                                            Examinateur

Nicola Nadeau                                 University of Sheffield                               Examinatrice

Christine Andraud                            CRC, MNHN                                             Invitée

Marianne Elias                                 ISYEB, CNRS                                           Invitée

Claire Doutrelant                              CEFE, CNRS                                            Directrice de thèse

Doris Gomez                                    CEFE, CNRS                                            Directrice de thèse