| Organisms modify their environment through their activities and by doing so, they modify evolutionary pressures acting on them, as well as the ecological conditions under which they grow and reproduce. Niche construction, as defined by Odling-Smee et al. (2003), is a concept that captures the reciprocal organism-environment interaction from an evolutionary perspective. However, niche construction in the sense of biotically-driven improvement of the ecological environment has been poorly explored to date. I derive a consumer-resource model to investigate the consequences of niche construction for its agent. I show that niche construction is a mechanism by which a species enhances its ecological persistence, via positive ecological feedbacks, and partially regulates its environment against external changes, via adaptive feedbacks. Next, I integrate niche construction into traditional competition models. A species that improves the level of a limiting niche factor via niche construction simultaneously competes with adjacent species via deteriorating impacts on the level of the same or other limiting niche factors. I observe that the interplay between niche improving and niche deteriorating impacts modifies the potential for species coexistence. Moreover, I show that the niche constructing species has a facilitative effect on the equilibrium abundance of its competitor. The prevalence of the facilitative effect, however, depends on both species' competitive hierarchies and the fertility of the ecosystem. Finally, I derive a model to investigate the evolution of the strength of facilitation between two competing species, when one species improves abiotic conditions to the advantage of its competitor but without any benefit to itself. In this case, I predict that high strength of facilitation evolves in productive ecosystems. Overall, my thesis provides a novel framework for the investigation of niche improving and niche deteriorating impacts and their combined effects on species coexistence, community structure and ecosystem functioning. |
