Kiers et al. (1) make three main points. First, they noted that many mutualisms involve multiple symbionts interacting with a single host. We agree, and we explained that partner fidelity feedback (PFF) can function because plants generally “limit, withdraw, or even abscise investment in shoots, flowers, and roots (or subsets of any of these) after physical damage or deficits of… resources…” (2). This “modularity” of plant hosts (3) separates the effects of different symbionts and allows the host to react to individual symbionts. Modularity is easily incorporated into our model, because (with no change in our results) principal-agent theory allows the assumption of one agent per host to be replaced …Organismic and Evolutionary Biolog
