Special Issue

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

  • Adrian Stencel (Jagiellonian University)


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.

Keywords: symbiosis, heritability, symbiogenesis, niche construction

How to Cite:

Stencel, A., (2022) “Why the Evolution of Heritable Symbiosis Neither Enhances Nor Diminishes the Fitness of a Symbiont”, Philosophy, Theory, and Practice in Biology 14: 4. doi: https://doi.org/10.3998/ptpbio.2098



Published on
25 Jan 2022
Peer Reviewed