Diet and Diversification in the Evolution of Coral Reef Fishes

Abstract

The disparity in species richness among evolutionary lineages is one of the oldest and most intriguing issues in evolutionary biology. Although geographical factors have been traditionally thought to promote speciation, recent studies have underscored the importance of ecological interactions as one of the main drivers of diversification. Here, we test if differences in species richness of closely related lineages match predictions based on the concept of density-dependent diversification. As radiation progresses, ecological niche-space would become increasingly saturated, resulting in fewer opportunities for speciation. To assess this hypothesis, we tested whether reef fish niche shifts toward usage of low-quality food resources (i.e. relatively low energy/protein per unit mass), such as algae, detritus, sponges and corals are accompanied by rapid net diversification. Using available molecular information, we reconstructed phylogenies of four major reef fish clades (Acanthuroidei, Chaetodontidae, Labridae and Pomacentridae) to estimate the timing of radiations of their subclades. We found that the evolution of species-rich clades was associated with a switch to low quality food in three of the four clades analyzed, which is consistent with a density-dependent model of diversification. We suggest that ecological opportunity may play an important role in understanding the diversification of reef-fish lineages.

The evolution of fishes and corals on reefs: form, function and interdependence

“…1), and mirrors the relatively low rates of diversification in a wide range of reef fish taxa (e.g. Alfaro et al, 2009;Cowman & Bellwood, 2013a,b;Lobato et al, 2014). This stasis in early Cenozoic reefs is also reflected in their biogeography.…”

“…Recent data on genera from Allen & Robertson (1994) and Randall, Allen & Steene (1997). (Floeter et al, 2008;Cowman & Bellwood, 2011), or inferred trophic ecology (Cowman, Bellwood & van Herwerden, 2009;Bellwood et al, 2014aBellwood et al, ,b, 2015aLobato et al, 2014). These changes were summarized for reef fishes in Bellwood et al (2015b) where six phases were identified.…”

“…The expansion of coral-feeding fishes in the late Miocene , appears to be part of a broader trophic rearrangement during this period (Lobato et al, 2014) and it is in the use of new food resources that the greatest changes on reefs are seen. There are two distinct elements that underpin these changes: (i) the rise of small fishes, and (ii) an increase in the use of small food items.…”

“…In fishes, this includes details of the timing of lineage diversification (e.g. Alfaro et al, 2009;Gaither et al, 2014;Lobato et al, 2014), historical biogeographic patterns (e.g. Barber, 2000;Cowman & Bellwood, 2013a), the evolutionary consequences of reef association (e.g.…”

Phylogenetic perspectives on reef fish functional traits

“…These studies have addressed aspects of functional diversity that are important to reef conservation, encompassing functional insurance, redundancy, and ecosystem services (Micheli et al., ; Mouillot et al., ; Parravicini et al., ). In parallel, phylogenetic studies have examined the evolutionary patterns of a variety of traits in reef fish lineages, aligning their findings to key historical and biogeographical events and evolutionary processes that have shaped reef fish functional diversity (Alfaro et al., ; Erisman, Craig & Hastings, ; Bellwood et al., ; Price et al., ; Frédérich et al., ; Lobato et al., ). Community phylogenetics combines ecology with phylogeny to offer a framework to examine the functional history of an assemblage, but also to address how assemblage structure and function are shaped by evolutionary processes.…”