Missions

Identifying the ecological factors involved in sympatric speciation is a major research avenue in evolutionary biology. Comparing allopatric and sympatric populations of closely-related species provides a way to distinguish among traits involved in triggering speciation vs. traits evolving after secondary contact between closely-related species, because of reinforcement of barriers to gene flow. Closely-related species living in sympatry indeed often display divergent evolution of mating cues and preferences, because of the costs incurred by heterospecific reproductive interactions. In butterflies sharing similar coloration, significant heterospecific courtship and male-male competition are often observed, because visual cues often trigger such behavioural responses. In mimetic species, pheromones divergence and olfactory receptors are thus predicted to be under divergent selection in closely-related species living in sympatry.
Thie postdoctoral project focuses on the evolution of olfactory receptors in Morpho butterflies, a neo-tropical genus where multiple species co-exist in sympatry. Among some sympatric species, a parallel evolution of dorsal color pattern has been observed (Llaurens et al. JEB, 2021) and substantial heterospecific interactions caused by similarity in color pattern have been documented (le Roy et al. 2021). We thus predict a divergent evolution of olfactory receptors, specifically in closely-related species living in sympatry.

Activités

The postdoctoral project will follow two main axis :
1. Investigating the diversification of olfactory receptors in sympatric species
The diversification of OR genes will be studies both within the genus Morpho and at larger macroevolutionary scale. The team has already assembled and annotated the genomes of 11 out of the 30 Morpho species, and multiple genomes of Lepidoptera are not available in public databanks. The recuited postdoc will specifically detect OR gene duplications, losses and copy number variations (CNVs) among the selected species and test for signatures of divergent evolution in sympatric species.
2. Differential expression of OR genes in sympatric species
It has recently been observed that the females of the two sister-species M. helenor and M. achilles sampled in French Guyana have highly similar chemical profiles while males from these two species display drastically different profiles. The postdoc will thus investigate whether the females of these two species express different ORs, using a transcriptomic approach on antennae.

Compétences

We are seeking a motivated candidate with a PhD in chemical ecology and experience in insect pheromone communication. We are looking for someone who is interested in the question of reproductive isolation between sympatric species. The ability to work in a team is essential for this postdoctoral project, which is part of a larger research project funded by the ERC.

Contexte de travail

The postdoc will work in the Center for Interdisciplinary Research (CIRB) in Biology at College de France in Paris, and participate to the ERC project OUTOFTHEBLUE, leaded by Violaine Llaurens. The CIRB is an interdisciplinary institute, gathering different fields of biology, from developmental biology, neuroscience and evolutionary ecology, aiming at building original and synergetic research. Numerous international students and postdoc work at CIRB, creating a stimulating international environment. The CIRB is ideally located in Paris city center, with a rich live and cultural atmosphere.

Contraintes et risques

The postdoctoral project will have an important low-risk part involving bioinformatics. The field experiments in tropical conditions will required medical survey before and after the mission and a specific training towards health risk in the tropics.