Assistant Professor Rutgers University Newark Newark, New Jersey, United States
Abstract: Symbiosis was first defined by de Bary in 1879, and since then, has been used to describe many systems, both biological and otherwise. The definition of symbiosis is often altered, and the word is often misused. There have been multiple attempts to clarify the concept, and here I will present my attempt at this, using a new conceptual framework across three dimensions, which manifests as a cube. In my concept, I describe the three essential axes to consider in any symbiotic relationship: fitness effects (ranging from mutualism to parasitism), partner fidelity (ranging from obligate through facultative to no association) and symbiont transmission mode (ranging from vertical through horizontal and environmental acquisition). With creating this framework, several hypothesized rules, and a variety of patterns emerge, which allow us to understand patterns of symbiosis across a diversity of systems. The most important rule that emerges from this conceptual framework is that the location of a relationship on particular axis, and thereby the location in the symbiosis cube, will vary depending on context. This is in contrast to many descriptors of symbiotic relationships as falling into discrete categories: either obligate or facultative, either vertically transmitted or environmentally acquired, and either a mutualism or parasitism. Instead, I argue that factors such as environment, nutrient inputs, host immune systems, other community members, etc. can affect where a symbiotic relationship falls on different axes. This conceptual framework can be a valuable tool for teaching about symbiosis and in formulating hypotheses for future studies.
