How Research on Symbiosis Should Transform Our Understanding of Adaption

Evolutionary Biology has mostly relied on a ‘Modern Synthesis’ theoretical foundation that has not changed much since it was proposed by population geneticists and other biologists in the first half of the 20^th Century. For most evolutionary biologists, intergenerational change was mediated almost exclusively through genetic change between generations. Various research projects aimed at weakening that assumption by showing how non-genetic inheritance played a non-trivial role in trait formation and transmission: this gave rise to various attempts to enrich, transform or even supplant the ‘Modern Synthesis’ that played such a key role in our understanding of evolutionary processes. Be it Developmental System Theory, or some epigenetics research programme, niche construction, or even evo-devo to some extent, the centrality of intergenerational genetic change to our understanding of adaptation has been relativized. But all those projects still focus on species or biological systems with relatively homogenous lineages. What has not been fully appreciated is how much symbiosis (especially at the microbiological level) shows the limitations of any attempt to reduce the process of adaptation to within lineage change. Symbionts are in many respects modular traits that can be passed on vertically or horizontally in ways that clearly affect the evolutionary success of the communities they are involved in. Symbiosis has a process of generating new cohesive biological units (new evolutionary individuals) shows the limitation of focusing the study of adaptation exclusively on continuous cohesive genetic units of same species organisms.  Inspired by John Dupré an O'Malley's work on the philosophy of microbiology and systems biology, we will see how the common functional history becomes more useful than common genetic history to assess the evolution of many of complex biological systems. Epistemological lessons for the development of systems biology will also be drawn: if the functional description of evolutionary individuals becomes more theoretically fruitful than the genetic descriptions of evolutionary individuals, systems biology should take very seriously its ‘systems driven’ research agenda rather than focusing too much on the ‘genetically’ data-driven research agenda.