Cutting-edge gene analysis has produced evidence that profound changes took place in reef fish communities about 20 million years ago, reshaping our understanding of coral reef evolution.
James Cook University's Associate Professor and Queensland Museum's Principal Scientist and Curator of Marine Biodiversity, Dr Peter Cowman, was a co-author of the study. He said marine diversity – the variety of life in an ocean - is disproportionately concentrated in coral reefs, which makes understanding its origins critical.
"Investigating the origins of this exceptional diversity is crucial for predicting how reefs will respond to current and future disturbances," said Dr. Cowman.
Scientists used a genome-scale dataset to reconstruct the evolutionary history of wrasses and parrotfishes. The study, published in Science Advances, provides the most detailed evolutionary tree of this fish group to date.
"The Labridae family, which includes the wrasses, hogfishes, razorfishes and parrotfishes, is one of the most species-rich and ecologically diverse living marine fish clades and a major component of reef vertebrate diversity," said Dr Cowman.
"Their functional roles are incredibly important for reef health."
He said the genomic data capture was made possible by funding from the government's Australian Research Council through the Discovery Early Career Researcher Award.
"One of the key strengths of this work is the breadth of our sampling. By including nearly 60% of all known labrid species, we've captured a much more complete picture of the family's evolutionary history than previous studies," said Dr Cowman.
"This detailed phylogeny allows us to explore the timing of key innovations in this group, like the evolution of specialized feeding strategies."
Lead author Chase Brownstein, a PhD candidate at Yale University's Department of Ecology and Evolutionary Biology, said genome-scale datasets have the power to reveal secrets about major events in the evolution of living lineages of organisms.
"In this case, we used a massive dataset of over 400 species to show that wrasses and parrotfishes experienced a remarkable explosion of diversification starting about 20 million years ago, during the Early Miocene," said Mr. Brownstein.
Professor Thomas Near from Yale University, a co-author on the study, added, "These findings revise our understanding of the timeline of reef fish evolution. The Early Miocene appears to have been a pivotal period, with a burst of diversification across multiple reef fish lineages, not just wrasses."
Scientists are still unsure of the precise underlying reason the diversity explosion happened, but the study suggests it was linked to major ecological changes on reefs. Some think it may be linked to plate tectonics changing the availability and configuration of marine habitats and the development of the Indo-Pacific biodiversity hotspot after successive continental collisions.
Dr Cowman said understanding evolutionary history allows us to appreciate the intricate connections between fish diversity and reef health.
"The ecological importance of Labridae cannot be overstated. They contribute to essential processes like herbivory, predation, cleaning symbiosis and bioerosion, all of which are vital for the resilience and functioning of coral reef ecosystems.
"Conserving these remarkable fishes is crucial for safeguarding the future of coral reefs," said Dr Cowman.
