Delineating reef fish trophic guilds with global gut content data synthesis and phylogeny

Abstract

Understanding species’ roles in food webs requires an accurate assessment of their trophic niche. However, it is challenging to delineate potential trophic interactions across an ecosystem, and a paucity of empirical information often leads to inconsistent definitions of trophic guilds based on expert opinion, especially when applied to hyperdiverse ecosystems. Using coral reef fishes as a model group, we show that experts disagree on the assignment of broad trophic guilds for more than 20% of species, which hampers comparability across studies. Here, we propose a quantitative, unbiased, and reproducible approach to define trophic guilds and apply recent advances in machine learning to predict probabilities of pairwise trophic interactions with high accuracy. We synthesize data from community-wide gut content analyses of tropical coral reef fishes worldwide, resulting in diet information from 13,961 individuals belonging to 615 reef fish. We then use network analysis to identify 8 trophic guilds and Bayesian phylogenetic modeling to show that trophic guilds can be predicted based on phylogeny and maximum body size. Finally, we use machine learning to test whether pairwise trophic interactions can be predicted with accuracy. Our models achieved a misclassification error of less than 5%, indicating that our approach results in a quantitative and reproducible trophic categorization scheme, as well as high-resolution probabilities of trophic interactions. By applying our framework to the most diverse vertebrate consumer group, we show that it can be applied to other organismal groups to advance reproducibility in trait-based ecology. Our work thus provides a viable approach to account for the complexity of predator–prey interactions in highly diverse ecosystems.

Phylogeny, body morphology, and trophic level shape intestinal traits in coral reef fishes

“…Coral reefs host an extraordinary diversity of species. Among these species, fishes are the most diverse and prominent vertebrates, exhibiting a wide array of morphologies and trophic strategies (Alfaro et al, 2007;Cowman et al, 2009;Floeter et al, 2018;Parravicini et al, 2020;Price et al, 2011Price et al, , 2013Siqueira et al, 2020).…”

“…Coral reefs host an extraordinary diversity of species. Among these species, fishes are the most diverse and prominent vertebrates, exhibiting a wide array of morphologies and trophic strategies (Alfaro et al., 2007 ; Cowman et al., 2009 ; Floeter et al., 2018 ; Parravicini et al., 2020 ; Price et al., 2011 , 2013 ; Siqueira et al., 2020 ). Given this multitude of feeding behaviors, reef fishes represent an ideal group to study how evolutionary and ecological mechanisms influence intestinal morphology.…”

Response and Effect Traits of Coral Reef Fish

“…Rather, species are assigned a diet category post data collection using expert knowledge, published literature, or databases such as Fishbase (e.g., MacNeil et al, 2015). More recently, Parravicini et al (2020) highlight the disagreement in the literature about broad reef fish trophic guilds, and provide a standardized set of diet classifications using phylogeny and maximum body size to predict trophic guild with high accuracy. However, improvements can still be made by accounting for intraspecific variation.…”

Feeding habits and seasonal trophic guilds structuring fish community in the bay mouth region of a tropical estuarine habitat

“…Understanding mechanisms behind the maintenance of ecosystem function is fundamental in ecology (Reiss et al, 2009;Parravicini et al, 2020).…”

“…Trophic relationships are elements describing energy transfer in the ecosystem (Ramírez et al, 2013) and feeding strategy among species within the food web (Frances & McIntyre, 2017). Knowing species' role in a food web requires accurate assessment of their trophic niche or guild (Root, 1967;Parravicini et al, 2020). Elliott et al (2007) classified seven estuarine fish guilds or feeding mode functional groups (FMFG), which includes detritivores, herbivores, omnivores, zooplanktivores, zoobenthivores, piscivores and miscellaneous/opportunists.…”