Metacommunity Structure, Species Richness, and Guild Composition of Reef Fish along an Extensive Latitudinal Gradient in the Tropics: A Hierarchical Approach
Compartmentalized structures. Brazilian Biogeographic Province. Clementsian Structure. Clumped Species Loss. Coherence. Insularity. Nested Structure. Turnover.
Coral reef environments support a diverse fish fauna endangered by anthropogenic changes. Consequently, understanding the mechanisms that maintain diversity is important for informing conservation policy and management. A metacommunity approach acknowledges the interactive nature of communities along gradients and provides critical information about species distribution patterns at the mesoscale. As such, we quantified the structure of metacommunities relative to biogeographic region and insularity, identified latent environmental gradients associated with those metacommunities, and evaluated the extent to which structures are guild-specific. We divided the Brazilian Biogeographic Province into biogeographic regions defined by spatio-environmental characteristics and separately analyzed the distribution of fish species according to trophic guild affiliation. We then analyzed an ordinated (Reciprocal Averaging) site-by-species incidence matrix based on an Elements of Metacommunity Structure approach and did so for all fish and separately for each of the five trophic guilds. To decompose the effects of latitude from those associated with the biogeographic regions on analyses for the Province, we performed an Analysis of Covariance on ordinated site scores. Although considerable variation in species richness characterized the four biogeographic regions, guild composition did not differ significantly among them. Nonetheless, compartmentalized structures characterized the entire fish fauna of the Brazilian Province, and the position of sites along the latent environmental gradient was consistently related to the biogeographic region, latitude, or their interaction. This was generally true for the separate assessments of each trophic guild as well. Environmental filtering and dispersal barriers likely interact to affect the strong compartmentation of metacommunities at multiple scales.