The World is Green hypothesis, which stems from the classic work of Hairston, Smith and Slobodkin (1960), suggests that since herbivores are not limited by their food, they must instead be limited by their predators. While this is often considered an oversimplification of the drivers of community structuring, this idea has served as a foundation of ecological research and theory for many years. The authors proposed that trophic levels alternate between bottom-up and top-down control, such that plants and carnivores are both limited by resources while herbivores are limited by carnivores. This idea suggests that species interactions play a vital role in determining not only which species will be found but also how many of each species a community can support.
In the years following the HSS hypothesis, many ecologists used targeted experiments to begin teasing apart the relative influence of biotic and abiotic variables in determining community structure. One such example is Lubchenco and Menge (1978) that sought to disentangle the relative importance of disturbance and predation in coastal rocky intertidal systems. Their research suggests that while environmental factors and disturbance can set a baseline for the community composition, species interactions, like predation and competition, also play a vital role in shaping community structure.
Recent research has supported the idea that species interactions are vital drivers of community structuring. A 2015 article (Lima-Mendez et al) took a modern approach to exploring community structuring. Using global data from the Tara Oceans project, they argued that species distributions could not be predicted from environmental factors alone and that biotic interactions play a large role in structuring communities. They constructed interaction networks for plankton species and used experimental methods to validate predicted interactions. Utilizing techniques from microbiology and systematics, the authors were able to demonstrate that the organization of ocean food webs can be predicted from patterns of species co-occurrence.
These three papers took three very different approaches to understanding community structuring (theory, experiments, survey and synthesis), but I found it compelling that all three argued for more than environmental conditions shaping communities and highlighted the primacy of species interactions.