Why the Evolution of Heritable Symbiosis Neither Enhances Nor Diminishes the Fitness of a Symbiont

• Published in: Philosophy, theory, and practice in biology Vol. 14
• Main Author: Stencel, Adrian
• Format: Journal Article
• Language: English
• Published: Michigan Publishing 25.01.2022
• Subjects: heritability; niche construction; symbiogenesis; symbiosis
• ISSN: 2475-3025; 2475-3025
• DOI: 10.3998/ptpbio.2098

One of the current problems in microbiology concerns the understanding of fitness in host-symbiont systems. A great deal of research and conceptual work has analysed how the host benefits from such associations; however, very little of this work has attempted to take the microbial perspective. Nevertheless, some scientists have argued that we should conduct more comparative studies of both microorganisms that interact with a host and their free-living counterparts in order to determine whether or not symbiosis is beneficial for these microorganisms. In this paper, by means of analysing heritable symbiosis as a case study, I intend to provide a different perspective on this subject. Mainly, I argue that asking how the fitness of a given microorganism was changed during the evolution of heritable symbiosis may be theoretically unjustified at both the early and late stages of this process. The reason for this, I argue, is that, during the evolution of heritable symbiosis, the fitness of a microorganism becomes incommensurable with that of its free-living counterparts because their contexts become radically different; therefore, comparing their fitness makes little sense. My analysis is driven by the use of the ecological concept of fitness; accordingly, my conclusions are bound to this specific interpretation of fitness.