We are studying how animals’ shapes and behaviors are evolving. We are mostly interested in the mechanisms that give rise to new traits, and how these traits diversify between species. To address these general questions we are focusing on model traits associated with reproduction in Drosophila fruitflies, a group of species that is particularly amenable to genetic approaches and inter-species functional comparisons.


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Evolution and diversification of Drosophila wing pigmentation patterns

We are studying the formation and evolution of wing pigmentation patterns in Drosophila as a model to understand the evolution of morphological patterns in animals. The pigmentation patterns we are focusing on are present at the tip of the wing of several Drosophila species, almost exclusively in males. The wing spot has diversified in shape, color or intensity among species after it’s evolutionary emergence. This male-specific wing spot has evolved independently in several Drosophila lineages. In all cases, the wing spot is associated with a courtship display behavior during which the males extend one or two wings in front of the courted female. Such a display behavior is never observed in non-spotted Drosophila species.
We are studying the genetic and the developmental mechanisms underlying the emergence and the diversification of the wing spot in the Drosophila melanogaster lineage; and the repeated evolution of the wing spot in independent lineages (in particular the obscura group).
We have previously proposed that the evolution of the wing spot results from the assembly of a novel gene regulatory network, the establishment of new regulatory connections between transcription factors, encoded by patterning genes, and several downstream, effector genes. We are now aiming at characterizing this network, its components and their interactions, and more importantly, at understanding how this novel regulatory network has been assembled during evolution. We also want to unravel which modifications in this network are responsible for the observed diversification of the wing spot in the various species of the melanogaster group.
To address these questions we are employing various genetic and molecular technics, including comparative functional genomics coupled with bioinformatics, comparative gene function manipulations (using CRISPR-based or transgenic functional assays), biochemistry, and imaging.
Our overall ambition with this project is to better understand the relationships between genetic changes and phenotypic (eg morphological) modifications.

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Evolution of egg laying behavior of Drosophila suzukii, an invasive pest species

Animal species have to make important choices throughout their lives. One of them, for females, is to decide where to put their eggs. The vast majority of Drosophila species (more than 3000 species have been described) lay their eggs in rotting or decaying substrates -fruits, plants, cactus, or flowers, depending on species. One noticeable exception is Drosophila suzukii, an invasive species recently arrived in Europe (less than 10 years ago), which lay eggs both in rotten but also in fresh, ripening fruits. This species targets a large range of fruits, in particular strawberries, cherries, raspberries, grapes and more. By laying eggs inside the fruits, D. suzukii is responsible for substantial damages and economical loss to the fruit industry, wherever it is present.
We are studying the phenotypic modifications that enabled or accompanied the shift in the ecological niche of D. suzukii from rotten to ripening fruits. Among these modifications, the serrated ovipositor (the egg laying organ) has doubled in size compared to closely related species, allowing the flies to pierce through the stiff skin of ripening fruits. Such enlargement of the ovipositor is a fairly common on agricultural pest species targeting fresh fruits (the medfly Ceratitis capitata, or the olive fruit fly Batrocera olea are other famous examples), in which it has happened independently.
In addition to the enlargement of the ovipositor, the egg laying behavior of D. suzukii has changed compared to other species, as D. suzukii female are strongly stimulated to lay eggs on ripening fruits. We are studying the egg laying site choice and oviposition in D. suzukii using an interspecies comparative approach. We want to identify the cues that attract or stimulate egg laying in D. suzukii, and the sensory apparatus that respond to these cues.
Ultimately, we hope to better understand the genetic and neuronal changes responsible for innate behavior evolution, and how these changes drive or enable shift in the ecological niche that a particular species occupies.