Avis de Soutenance
Thomas AUBIER
Soutiendra publiquement ses travaux de thèse intitulés
Diversity of warning signals, speciation and clade diversification
Soutenance prévue le vendredi 14 septembre à 14h
Lieu : l'Amphithéâtre de la Délégation Languedoc-Roussillon du CNRS

The display of warning signals by unpalatable (or otherwise defended) prey provides a wonderful opportunity for estab-lishing an integrative view of biological diversification. Warning signals are known to be under strong natural and sexual selection. On the one hand, the sampling strategy of predators, characterized by a learned avoidance of signals associated with unpalatability, generates natural selection in favour of warning signals in high frequency in the prey community. Such positive frequency-dependent selection favours phenotypic uniformity and causes unpalatable species to converge on common warning signals (mutualistic "Müllerian" mimicry), as seen in a large panel of taxa. On the other hand, warning signals are used as a phenotypic cue for mate choice, generating sexual selection with important consequences for repro-ductive isolation and speciation.

Paradoxically, despite powerful selection favouring phenotypic convergence, warning signals are fantastically diverse, both within and between species, and this morphological diversification is often associated with extensive species diversification at the clade level. In this thesis, I tackle this apparent paradox from the ground up and I thereby refine our understanding of the role of positive frequency-dependent selection and mutualistic interactions for evolutionary diversification at micro- and macroevolutionary scales. First, I show that the predator sampling strategy can favour the emergence of diversity of warning signals despite positive frequency-dependent selection. Second, I dissect the conditions allowing the evolution of strong and stable reproductive isolation, necessary for speciation to occur, in a number of ecological situations where warning signals are under natural and sexual selection. Third, I highlight important indirect effects of frequency-dependent selection on diversification at macro-evolutionary scale via spatial constraints and by-product ecological convergence.

Keywords: frequency-dependent selection, mutualism, predator cognition, speciation, clade diversification, theory

Membres du jury:

M. Michael KOPP         Aix Marseille Université - CNRS UMR 7373 (I2M)         Rapporteur
M. Christophe THÉBAUD          Université Paul Sabatier - CNRS UMR 5174 (EDB)         Rapporteur
Mme Emmanuelle PORCHER          Museum National d'Histoire Naturelle - CNRS UMR 7204 (CESCO)         Examinatrice
Mme Carole SMADJA          Université de Montpellier - CNRS UMR 5554 (ISEM)         Examinatrice
M. Mathieu JORON         Centre d'Ecologie Fonctionnelle et Evolutive - CNRS UMR 5175         Directeur de these
Mme Marianne ELIAS          Museum National d'Histoire Naturelle - CNRS UMR 7205 (ISYEB)         Co-directrice de these

Yong ZHENG

Eleanor STERLING

Center for Biodiversity and Conservation, American Museum of Natural History, New York, USA

Le vendredi 10 novembre 2017 - 11h30 Grande Salle CEFE (1919 Rte de Mende, 1e étage, aille C)

(Seminar in English)

Pacific Island communities are facing unprecedented challenges in conserving natural resources and maintaining human well-being. In these place-based communities, biocultural connections, or the integrated social, economic, cultural and environmental linkages between people and nature are widely believed to play a critical role in improving and maintaining the resilience of both human and ecological communities. However, indicators of human or ecological well-being rarely reflect the integrated nature of these systems. Based on visioning exercises across multiple Pacific Island archipelagoes (Hawaiʻi, Fiji, Solomon Islands, Marshall Islands) on characteristics of vibrant biocultural landscapes and seascapes, we have identified key dimensions that describe a resilient biocultural state for Pacific Island communities and developed example indicators that measure the state of these dimensions. Additionally, we have assessed the United Nation's Sustainable Development Goals and the Convention on Biological Diversity's Aichi Targets to determine which of these goals or targets are relevant to Pacific Island communities. For goals or targets that were not obviously relevant, we have come up with recommendations for how they can be adjusted to be relevant or translated between local and global needs, in order to better resonate with communities and better reflect important connections between people and nature.

Recent publications:

Sterling et al. 2017 Biocultural approaches to well-being and sustainability indicators across scales.  Nature Ecology & Evolution

Sterling et al. 2017 Culturally Grounded Indicators of Resilience in Social-Ecological Systems Environment and Society: Advances in Research.

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