Ada Altieri

Ada Altieri

MSC-University of Paris

Ada Altieri obtained her Ph.D. in Theoretical Physics in February 2018 from both the University of Rome “Sapienza” and the University Paris-Sud XI co-advised by Giorgio Parisi and Silvio Franz. During her Ph.D. she focused on renormalization group techniques in disordered systems as well as on the connections between continuous constraint satisfaction problems and zero-temperature glassy phases in high dimensions. In November 2017 she moved to the Laboratoire de Physique Théorique of the École Normale Supérieure in Paris, obtaining a postdoctoral fellowship to work with Francesco Zamponi on the rheology of amorphous solids under shear deformations. Then, one year later she joined the team of Giulio Biroli dealing with various topics on which the Simons Collaboration “Cracking the Glass Problem” is based. In 2020 she was awarded the L’Oréal-UNESCO Fellowship for Women in Science for her research on the “Ecosystems’ complexity through the prism of statistical physics”. Since December 2020 she is Associate Professor in the Lab “Matière et Systèmes Complexes” at University of Paris.

Can a large well-mixed ecosystem be thought of as a glassy model?

Cases in which the number of interacting components is very large are becoming of general interest in disparate fields, such as in ecology and biology, e.g. for bacteria communities, as well as in complex economies where many agents trade and interact simultaneously. Many of these systems appear often to be poised at the edge of stability, hence displaying enormous responses to external perturbations. This feature, also known in physics as marginal stability, is usually related to the complex underlying network of interactions, which might induce critical behavior. In this talk, I will present the problem of ecological complexity by focusing on a reference model in theoretical ecology, the disordered Lotka-Volterra model with random interactions and finite demographic noise. Employing advanced statistical physics techniques, I will unveil a complex and rich structure for the organization of the equilibria and I will relate critical features and a slow relaxation dynamics to the appearance of disordered glassy-like phases. Finally, I will discuss the generalization of these results to non-logistic growth functions in the dynamics of the species abundances, which turn out to be of great interest for modeling intra-specific mutualistic effects. References: A. Altieri, F. Roy, C. Cammarota, G. Biroli, Phys. Rev. Lett. 126, 258301 (2021); A. Altieri, G. Biroli, arXiv:2105.04519 (2021), to appear in SciPost Physics.