The cost-benefit framework forms the basis for current theories on the evolution of group living in animals. Much attention has been paid to drivers of intraspecific grouping in vertebrates, with recent emphasis on heterospecific groups. However, a disproportionately large fraction of vertebrate taxa choose to remain solitary at all times. Using a secondary dataset on extant species of fish, birds and mammals, the first part of this study aims to identify the suite of traits that these solitary taxa are typically associated with, and the possible benefits gained from choosing to remain solitary.

Heterospecific grouping is a widespread phenomenon because it allows animals to exploit benefits such as protection from predators or access to key resources in a manner that is more effective and energetically efficient, while simultaneously reducing the costs of competition associated with conspecific grouping.

Tropical reef fish are a system where both single- and multi-species groups are seen. The ecological significance of the latter is poorly understood when compared to other vertebrate taxa. It has been proposed that such groups might be capable of impacting the overall trophodynamics of the reef by influencing benthic invertebrate and algal community structure. Our study is aimed at understanding the different drivers that influence mixed-species grouping in reef fish. We intend on assessing factors like morphology, phenotype, resource availability and predation risk to determine their role in shaping association patterns of shoaling reef fish groups using primary and secondary data, and a combination of empirical and simulation-based approaches.