Oral Presentation Australian Society for Fish Biology Conference 2024

More than one way to be a planktivore: the vast morphospace of plankton-feeding reef fishes (111378)

Isabelle Ng 1 , David R Bellwood 1 , Jan M Strugnell 2 , Alexandre C Siqueira 1 3
  1. Research Hub for Coral Reef Ecosystem Functions, College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
  2. Centre for Sustainable Tropical Fisheries and Aquaculture, College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
  3. Centre for Marine Ecosystems Research, School of Science, Edith Cowan University, Joondalup, Western Australia, Australia

Planktivorous reef fishes have been suggested to possess unique morphological traits to feed on small, evasive prey. However, despite the multitude of family-level studies addressing this hypothesis, results remain inconclusive. Our goal was to determine whether specialised traits and patterns of morphological convergence hold true across a comprehensive phylogeny of reef fishes. We measured 16 morphological traits, hypothesised to be important for plankton-feeding, from 815 images of 299 species in 12 global reef fish families. Using phylogenetic comparative methods, we then mapped the evolution of planktivory across reef fish lineages; assessed the effect of planktivory on the overall reef fish body shape; and tested for the presence of morphological convergence related to planktivory. We demonstrate that planktivory is evolutionary ubiquitous; it occurs in all 12 of the global reef fish families and first arose at least 53 million years ago. An overall effect on body shape between planktivores and non-planktivores was detected, but differences between groups were unremarkable and inconsistent across families. Contrary to previous assumptions, these findings suggest that planktivores encompass the entire morphospace of reef fishes and are not converging towards a distinct body shape. Instead, reef fishes of any shape and size can navigate the challenges of plankton-feeding.