 A different ontological framework links development and evolution through the entity of the acting organism (Nicholson 2014, 2018; Walsh 2015; for discussion, see Pradeu 2016; Baedke 2019a, 2019b). These approaches usually are less related to symbiosis research than to studies on niche construction or maternal effects. Here the organism (e.g., a beaver that builds a dam or an earthworm that processes the soil) is constructed as a self-determined agent that through its behavior modulates the selection pressures acting on it (Odling-Smee et al. 2003; Uller &amp; Helanterä 2019). Thus, so the argument goes, it can bias and direct population dynamics. The holobiont perspective and the niche construction perspective join together when one appreciates that the microbes and the host form each other’s environment. Here, the host and the microbes scaffold each other’s development and evolution (Chiu &amp; Gilbert 2015, 2020). 