In this series on symbiosis, we’re taking a deep dive into the many different types of relationships organisms have evolved into, the good, the bad, the benign. This episode highlights relationships in which one partner’s a total dud: behold the neutral symbiont. The relationships can be the result of complete and totally unbalanced competition where the other symbiont is harmed (amensalism) or when one species exploits and is benefitted by the resources offered up by the other at no cost to the latter (commensalism: think dung beetles). No species is entirely isolated from the impact of another organism in its environment so we’ll talk about that gray space between commensalism and mutualism, amensalism and exploitation. Welcome to the Single Acorn.