Multicellular Life Cycles as an Emergent Property in Filamentous Bacteria

Abstract

Multicellularity is an integral part of all organisms that grow to be larger than microscopic scales and is a necessity for complex morphologies. Hence, a central question is: what are the conditions that can lead to the evolution of multicellular development? Here, we outline a theoretical framework that serves as basis to understand the interactions that can lead to the evolution of multicellular life cycles in simple filamentous organisms. By assuming the prior evolution and existence of filamentous multicellularity, and not considering a priori selective advantages, we explore the extent to which intrinsic processes such as cellular birth and death rates can drive the development of such multicellular organisms. The chapter offers an overview of our mathematical setup and of the validation experiments in natural populations of filamentous bacteria. These studies show the presence of a common pattern in terms of filament growth, which provides a hypothesis for the emergence of primitive multicellular life cycles in simple organisms.