More than one way to be a planktivore: the vast morphospace of plankton-feeding reef fishes

Abstract

Planktivorous reef fishes are thought to possess unique morphological traits to feed on small, evasive prey. Despite the multitude of family-level studies addressing this hypothesis, results remain inconclusive. Our goal, therefore, was to determine whether specialised traits and patterns of morphological convergence are congruent across a comprehensive phylogeny of reef-associated fishes. We measured 15 morphological traits from 815 images of 299 species in 12 globally distributed families. Using phylogenetic comparative methods, we mapped the evolution of plankton-feeding across lineages; assessed the effect of planktivory on body shape; and tested for the presence of morphological convergence among planktivores. We demonstrate that planktivory is evolutionary ubiquitous and occurs in 12 of the most abundant global families. Some morphological trait differences between planktivores and non-planktivores were detected, but there was no difference in overall body shape. Contrary to longstanding assumptions, we show that planktivores have not converged towards distinct morphologies, but instead encompass the entire morphospace of reef fishes. Due to their behavioural, spatial, temporal, and resource heterogeneity, reef fishes of any shape and size can readily navigate the challenges of plankton-feeding. Graphical abstract

Bibliographic Information