What constitutes a community? A co-occurrence exploration of the Costa Rican avifauna

The concept of a community as a form of organization for natural biological systems is both widespread and widely accepted within the ecological and biological sciences. Communities have been defined as groups of organisms that interact in ways that denote interdependence between individuals and taxa (e.g. as defined by food webs) but they have also been defined as groups of co-occurring organisms that are assumed to interact by virtue of their shared spatiotemporal existence. The latter definition has been debated and challenged in the literature, with mounting evidence for co-occurrence being more indicative of coincident ecological niches in space and time rather than being evidence of ecological interaction or dependency. Using a dataset of 460 Costa Rican bird species divided into breeding and non-breeding season datasets, we empirically demonstrate the ways in which co-occurrence can create illusory communities based on similar occupied ecological niches and similar patterns of co-occurrence at different times of year. We discuss the importance of discerning coincidental co-occurrence from true ecological interactions that would manifest a true community, and further address the importance of differentiating communities of co-occurrence from communities of demonstrable ecological interaction. While co-occurrence is a necessary aspect of interspecific interactions, we discuss and demonstrate here that such co-occurrence does not make a community, nor should explicit patterns of co-occurrence be seen as evidence for evolutionarily important ecological interactions.

Automated summary

The concept of a community as a form of organization for natural biological systems is widely accepted within the ecological and biological sciences. However, the definition of a community based on co-occurrence has been debated, with evidence suggesting that co-occurrence is more indicative of coincident ecological niches rather than ecological interactions. Through a study on Costa Rican bird species, we demonstrate how co-occurrence can create illusory communities based on shared ecological niches and patterns of co-occurrence at different times of year. We emphasize the importance of distinguishing coincidental co-occurrence from true ecological interactions and differentiating communities of co-occurrence from communities of demonstrated ecological interaction.