Fossil evidence suggests that fish-based herbivory on coral reefs was established about 50 Ma in the Eocene, marking the time when many modern reef fish families are first recorded in the fossil record. Yet, our understanding of the evolution or historical development of reef herbivory is in its infancy.
#FISH CPLOT SIZE SURGEONFISH DRIVER#
Herbivory appears to be the single most important driver of benthic community composition on coral reefs and is often the main mechanistic link between human activity and coral reef decline.
Fish-based herbivory has been implicated in many key aspects of coral reef ecology, including coral recruitment, algal growth and coral recovery after climatic disturbances. However, one process stands out as critically important: the removal of algae by fishes. The complexity of these highly diverse ecosystems creates challenges in identifying ecosystem processes and the roles of organisms in shaping them. Although, it is hard to quantify the nature, importance and strength of ecological processes, especially in high diversity systems, it is the changes in ecological processes over time that most clearly reveal factors that underpin the establishment and maintenance of today's ecosystems.Ĭoral reefs provide a good example. However, it is increasingly recognized that it is ecological processes, not species, that shape the evolution of ecosystems.
#FISH CPLOT SIZE SURGEONFISH DRIVERS#
As a result, we have a good understanding of changes in taxonomic richness over time and the underlying drivers of change. The radiation of these new forms, and their expansion into new habitats in the Oligocene–Miocene, reflects the second phase in the development of fish herbivory on coral reefs that is closely associated with the exploitation of highly productive short algal turfs.īiodiversity, or more specifically taxonomic richness, is often used as a metric for describing changes in ecosystems through time. Today, these forms dominate coral reefs in both abundance and species richness and are associated with feeding on shallow, exposed algal turfs. Although Eocene surgeonfishes likely played a critical role as herbivores during the origins of modern coral reefs, they lacked the novel morphologies seen in modern Acanthurus and Siganus (including eyes positioned high above their low-set mouths). These long-snouted Eocene species were probably pair-forming, crevice-feeding forms like their Recent counterparts. Eocene and Recent surgeonfishes showed remarkable similarities, with grazers, browsers and even specialized, long-snouted forms having Eocene analogues. Using ecologically relevant morphological metrics, we investigated the evolution of herbivory in surgeonfishes (Acanthuridae) and rabbitfishes (Siganidae).
The evolution of ecological processes on coral reefs was examined based on Eocene fossil fishes from Monte Bolca, Italy and extant species from the Great Barrier Reef, Australia.
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