Species at the extremes of the food chain evolve faster, study says

December 17, 2018, University of Tennessee at Knoxville

Reef fish species at the extremes of the food chain—those that are strict herbivores or strict fish predators—evolve faster than fish species in the middle of the food chain with a more varied diet, according to a new study published in Nature Ecology and Evolution.

The paper, co-authored by Samuel Borstein, a Ph.D. candidate in the Department of Ecology and Evolutionary Biology, could challenge the way scientists think about evolution in relation to the position a species holds on the food chain.

Up until now, scientists thought that species that eat a wide variety of different foods might evolve quicker and show more variations in morphology—physical aspects such as size, shape, and color.

However, Borstein and his team were able to prove the exact opposite: species with the most limited diet are evolving faster.

For the study, the researchers produced an evolutionary "family tree" that describes the relationships of more than 1,500 coral reef species, their place in the food chain, and the diversity of items on which they feed.

They also digitized hundreds of photographs of reef fish to gather information on physical traits that are important for feeding, such as the depth of the peduncle (the part of the fish where body and fins attach).

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