Theoretical Principles for the Evolution of Collective Organization

Abstract

Collective systems that are biological individuals in their own right, such as multicellular organisms and social insect colonies, exhibit wide diversity in key organizing principles—including collective growth and reproduction, task allocation, communication, and spatial organization. This dissertation develops a number of new theoretical approaches to explore the proximate and ultimate factors shaping this organizational diversity. Chapters 1 and 2 focus on the role of ancestral constraints and ecological conditions, and use a bottom-up approach to the evolution of multicellularity to reveal how diverse multicellular life cycles could have emerged via the co-option ancestral gene regulatory mechanisms. Chapters 3 and 4 explore the role of ecology, and develop ecologically explicit models of dynamic collective organization to show how diverse strategies for task allocation (Chapter 3) and communication (Chapter 4) can be interpreted theoretically as adaptive responses to different environmental circumstances. Finally, Chapter 5 investigates the role of development, and integrates pattern formation models with empirical data to show how the evolutionary diversification of rodent stripe patterns has been shaped by the underlying developmental processes. Altogether, the work in this dissertation contributes to our understanding of how and why diverse forms of collective organization have evolved.