Structural and organisational conditions for the appearance of a functionally integrated organisation in the transition from prokaryotic to eukaryotic cell

Abstract

The concept of ¿functional (or physiological) integration¿ is explanatorily relevant to both biology andphilosophy of biology, but it suffers from two main related problems: first, it is an umbrella termencompassing any causal interdependence of functions, thus being unsuitable for characterisingbiological organisations as physiologic units; secondly, it lacks a unified theoretical framework tounderstand this concept. This PhD thesis aims to investigate the relationship between functionalintegration and biological individuality by studying the nature and the role of physiological integration inone of the major evolutionary transitions: the origin of the eukaryotic cell from the prokaryotic one. Themethodology employed is the so-called ¿organizational approach¿ that combines the descriptive approachof the methodological naturalism with the normative evaluation of the epistemic and practicalconsequences of the theoretical frameworks of life sciences. At the core of this work is the examinationof the physic-chemical and structural-functional conditions that allowed the transformation of aprokaryote into a eukaryotic cell and that determined a very specific kind of functionally integratedorganisation in eukaryotes. The thesis puts forward a theoretical proposal for functional integrationconsisting in the global capacity, enabled by specific spatial constraints, of a biological organisation toperform system-level regulation, spatio-temporal coordination of the parts, and system-levelreproduction. This proposal for functional integration has important consequences for understandingimportant issues of theoretical biology and philosophy of biology, such as biological individuality,biological autonomy, and major transitions in evolution.