Ecomorphological diversification in reef fish of the genus Abudefduf (Percifomes, Pomacentridae)

Abstract

Coral reefs are home to the most diverse fish assemblages on earth. This high diversity has been hypothesized to partially result from fine-scale niche partitioning of resources. Because niche partitioning might be facilitated by phenotypic diversity, analysis of the morphological variation in an evolutionary context can contribute to our understanding of the speciation and diversification of reef fish. Damselfishes (Pomacentridae) are an extremely diverse group of reef fishes, and Abudefduf genus is one of the youngest clades of this family. Abudefduf is basal clade group benthic feeders, feeding on algae, small benthic invertebrates and zooplankton. In contrast, more derived clades feed primarily on zooplankton. In this study, we examine the relation between morphological and ecological variation to determine the main forces driving diversification in Abudefduf. Results support clear ecomorphological segregation among basal and derived clades, indicating evolution from benthic feeders to zooplanktivorous feeders, suggesting that the shift to a new trophic niche was an important event driving diversification in Abudefduf, and also evidenced by the presence of morphological traits that represent specialized adaptations to chase plankton in the water column. Our analysis demonstrates the utility of morphological and ecological studies to understand the diversification process of reef fish.