This talk has been held during the Workshop “The physics of complex systems IV: from Padova to the rest of the world and back”.
You can find here the slides I have shown during the talk.
The theoretical study of ecosystems was born around forty years ago, and even if it has flourished lately there are still many problems that have not been solved. From an experimental point of view, in particular, microbial ecosystems have often been used as a testing ground for ecological models since they are relatively easy to set up and manage in the lab. The mathematical tool that has been used since the ‘70 in order to describe competitive ecosystems (especially microbial ones) is MacArthur’s consumer-resource model, which has been studied in many different versions and conditions but is still incapable to account for many important experimentally observed phenomena. In particular, all the versions of the model that have been studied suppose that the “metabolic strategies” of the species, i.e. their “eating habits”, are fixed and do not change in time; however, from many experiments on microbial species we know that this is not true, and that bacteria can modify their diets depending on the surrounding environmental conditions. In this talk I will present what has been the topic of my Master’s thesis and on which I am currently working for my PhD: I have taken MacArthur’s model and modified it so that metabolic strategies can change in time following a properly defined equation. As I will show, this simple modification allows the model to correctly describe many experimentally observed phenomena in microbial systems, like the existence of the so-called “diauxic shifts” and the violation of the “Competitive Exclusion Principle”.