Missions

--Multicellular organisms can adapt their phenotypes to environmental conditions by phenotypic plasticity. We address the link between phenotypic plasticity and fitness. We identified a suitable system: the splash-cup of the basal plant Marchantia polymorpha, an organ involved in dispersal. Vegetative propagules (gemmae) are dispersed away from the parent plant by raindrops bouncing off splash-cups. Are the morphologies of splash-cups optimal for dispersal?
The mission of the post-doctorant will be to characterize the dispersal efficiency of one splash-cup according to its geometry, in terms of number of gemmae dispersed and dispersal range. To do so, he will use experimental and theoretical approaches from fluid mechanics.

Activités

The Post-doctorant will use a setup done in the lab to produce drops of controlled size and velocity, and film their impact on splash-cups with two high-speed cameras. S.he will use 3D-printing pillars with a conical cavity that resemble Marchantia splash-cups. 3D-printing will enable a range of morphologies, first from already available 3D reconstructions of M. polymorpha or other Marchantia genus; 3D-nanoprinting will enable producing gemmae-like objects. Morphologies that are not observed in nature will also be considered, so as to assess optimality of natural cups. Drops will be produced with motorized syringes with characteristics based on averaged raindrops and then on measurements. An image analysis pipeline will be developed in Python to reconstruct 3D trajectories of the jet and ejected droplets from the 2 orthogonal views. Ejection kinematics (angles, velocities...) will be quantified according to the characteristics of impacting drops (size, speed) and to cup geometry (eg cone angle and diameter in simplified geometries).

Compétences

-Solid knowledge of fluids mechanics
-excellent skills for experimental work and analysis in Python
-good written and oral skills in English
-taste for interdisciplinary environments

Contexte de travail

-Interdisciplinary and dynamics laboratory
-fully equipped laboratory