How reptiles got their looks: the unreasonable effectiveness of computational models in skin scale and colour patterning

I will discuss how vertebrate skin colours and skin appendages (scales, feathers, hairs, ...) are patterned through Turing and mechanical instabilities. First, I will show that Reaction-diffusion (RD) models are particularly effective for understanding skin colour patterning at the macroscopic scale, without the need to parametrise the profusion of variables at the microscopic scales. I suggest that the efficiency of RD is due to its intrinsic ability to exploit continuous colour states and the relations among growth, skin-scale geometries, and the (Turing) pattern intrinsic length scale. Second, I will show that a three-dimensional mechanical model, integrating growth and material properties of embryonic skin layers, captures most of the dynamics and steady-state pattern of head scales in crocodiles.

Speaker: Michel Milinkovitch, University of Geneva