Population structure reduces the benefits from partner choice in mutualism

Mutualisms are key drivers of evolutionary and ecological processes. Understanding how different species can evolve to interact in mutually beneficial ways is an important goal of evolutionary theory, especially when the benefits require costly investments by the partners. For such costly investments to evolve, some sort of fitness feedback mechanism must exist that more than recoups the direct costs. Several such feedback mechanisms have been explored both theoretically and empirically, yet we know relatively little how they might act together, as they probably do in nature. In this paper, I model the joint action of three of the main mechanisms that can maintain symbiotic cooperation: part