Evolutionary history of the butterflyfishes (f: Chaetodontidae) and the rise of coral feeding fishes

Abstract

Of the 5000 fish species on coral reefs, corals dominate the diet of just 41 species. Most (61%) belong to a single family, the butterflyfishes (Chaetodontidae). We examine the evolutionary origins of chaetodontid corallivory using a new molecular phylogeny incorporating all 11 genera. A 1759‐bp sequence of nuclear (S7I1 and ETS2) and mitochondrial (cytochrome b) data yielded a fully resolved tree with strong support for all major nodes. A chronogram, constructed using Bayesian inference with multiple parametric priors, and recent ecological data reveal that corallivory has arisen at least five times over a period of 12 Ma, from 15.7 to 3 Ma. A move onto coral reefs in the Miocene foreshadowed rapid cladogenesis within Chaetodon and the origins of corallivory, coinciding with a global reorganization of coral reefs and the expansion of fast‐growing corals. This historical association underpins the sensitivity of specific butterflyfish clades to global coral decline.

Fifty million years of herbivory on coral reefs: fossils, fish and functional innovations

“…The observed changes in surgeonfish morphology and inferred abilities strongly support a proposed two-phase development of coral reef ecosystems, with the first wave in the Eocene and the second wave of highly specialized forms arising in the Oligocene or Miocene [8,9,20]. This second phase was originally characterized by the presence of feeding forms with strong links to fast-growing, highly productive components of the reef benthos [8,9,18,20,21]. It also coincided with an expansion of carbonate platforms in the IAA, an increase in the importance of Acropora in reef systems, a movement of marine biodiversity to the IAA and the rapid cladogenesis of major reef fish groups [3,4,8].…”

“…Although phylogenies have provided invaluable insights into the evolution of fish feeding on coral reefs [18,19], including herbivory [20][21][22], most of the detail is restricted to events during the last 30 Myr when most extant genera arose. Relatively little is known of the earliest origins of herbivory, and it is here that fossils are most useful in revealing both the taxa present and the morphological and inferred functional abilities of fishes at this time.…”

Evolution of long-toothed fishes and the changing nature of fish–benthos interactions on coral reefs

“…In the two key coral reef taxa (Ctenochaetus and combtooth blennies), molecular evidence indicates that these two lineages arose relatively recently (both within the last 25 My 38,39 ), suggesting that such specialized detritivory is a relatively new trait in reef fishes (the only other major detritivorous group on reefs, parrotfishes, likewise diverged relatively recently at about 16 Ma 40-42 , again with highly modified dentition). The third longtoothed group, the butterflyfish (Chaetodontidae), use their elongate, hooked teeth in batteries to form a 'Velcro-like' pad 43 , which allows them to feed on a wide array of small soft benthic items, from coral polyps and mucous to polychaetes (molecular evidence indicates that this group likewise diverged relatively recently with origins of the family about 32 Ma 44,45 ).…”

“…The rapid expansion of reefal taxa in the IAA 45,49 included fishes that exploit detritus-bearing algal turfs and fast-growing corals 44,45 . The latter following geographic expansion of fast-growing branching corals, especially Acropora species.…”

Spots and stripes: ecology and colour pattern evolution in butterflyfishes

“…These data were used to calculate a measure of dietary rspb.royalsocietypublishing.org Proc R Soc B 280: 20122730 complexity, which was the total number of foot items present in the diet of each species (range: 1-10). The categorization obligate corallivory [25] was used to determine whether there was a link between the evolution of corallivory and butterflyfish coloration. Information on the habitats of each species was used to rank substrates according to their visual complexity; 0 ¼ oceanic background (for species occuring in the water column), 1 ¼ sand, mud or silt substrates (e.g.…”