Job ID: 106465

PhD project – Neuronal bases of behavior evolution in Drosophila

Position: Ph.D. Student

Deadline: 2 April 2023

Employment Start Date: 3 October 2023

Contract Length: 3 years

City: Marseille

Country: France

Institution: Aix Marseille Université

Department: Institut de Biologie du Développement de Marseille (IBDM)


The NeuroSchool PhD Program of Aix-Marseille University (France) has launched its annual calls for PhD scholarships for students with a master’s degree in a non-French university.

The following project is one of the 14 proposed projects. Not all proposed projects will be funded, check our website for details.


State of the art: A central question in neurobiology is to understand at the genetic, molecular and cellular levels how neuronal circuits generate behaviors. Higher brain functions such as multi-sensory integration and decision-making processes are particularly poorly understood. In addition, how these functions are modified during evolution to promote the appearance of novel behaviors remains largely unknown. Which functional characteristics and circuit wiring principles evolve to change behavioral outputs? We can now address these questions by investigating the evolution of decision-making processes in Drosophila models.

We have developed a simple paradigm taking advantage of a divergence in egg-laying behavior (oviposition) between two genetically tractable fruit fly species. Most species including the model Drosophila melanogaster prefer to lay their eggs in rotten fruits, but the invasive pest Drosophila suzukii has evolved a novel preference for ripening fruits instead, causing important damage to the fruit industry worldwide. Using quantitative behavioral assays, chemically-defined oviposition substrates, neurogenetic tools and functional imaging approaches (calcium imaging), we have demonstrated that behavioral divergence is linked to differences in how sensory information is processed in the Central Nervous Systems (CNS) of these two species. More precisely, neuronal circuits controlling oviposition decisions in response to perception of fruit sugars appear to be tuned to different levels of activation in the two species.

Objectives: Our aim is to identify the molecular, cellular and circuit-level bases of differential sensory processing contributing to inter-species behavioral divergence. To that end, the proposed project will use new transgenic tools in D. suzukii to manipulate populations of CNS neurons homologous to those controlling oviposition behavior in D. melanogaster. We will then compare the physiological properties and functional role of these CNS circuits in oviposition decisions across species.

Methods and feasibility: Oviposition neurons can be targeted in D. melanogaster via expression of the Gal4 transcriptional activator under the control of specific gene regulatory elements. We will use these regulatory sequences and standard transgenesis approaches to generate Gal4 transgenic lines in D. suzukii targeting similar sets of neurons. We will then compare anatomical features of these neurons across species using available fluorescent UAS reporters and compare their function in oviposition behavior assays using neuronal silencing and activating transgenes. Neuronal physiological properties will be assessed via calcium imaging (GCaMP reporter) upon stimulation of the sugar-sensory neurons. All resources, methodologies, equipment and expertise are available in the host institute and team.

Expected results: We expect to observe anatomical, physiological and/or functional differences between species in CNS oviposition neuronal circuits providing a functional basis for inter-species divergence of behavior.

Candidate profile: The candidate should have solid background in neurobiology, microscopy and quantitative analyses. Expertise in dissection, genetics and behavioral studies will be an asset.