New research shines light on evolutionary variety of bioluminescent ocean fishes

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Matt Davis

Matt Davis

Bioluminescence -- the production of light from a living organism -- may be more widespread among marine fishes than previously thought, according to a study published June 8, 2016 in the open-access journal PLOS ONE by Matthew Davis from St. Cloud State University, United States, and colleagues. Most people may be familiar with bioluminescence in fireflies, but the phenomenon can be found throughout the ocean, including in fishes. Davis and colleagues analyzed nuclear and mitochondrial gene fragments from over 300 taxa to infer the number of independent evolutionary origins of bioluminescence and investigate diversification in these lineages.

Although this work focused only on ray-finned fishes, the authors found that bioluminescence may have evolved independently 27 times in 14 major fish clades -- groups of fishes that come from a common ancestor - and suggest that all fishes included in the study have been evolving bioluminescence since the Early Cretaceous, some 150 million years ago. The team also suggests that in some, but not all, cases, once an evolutionary line of fishes developed the ability to produce light, it soon thereafter branched into many new species.

"When things evolve independently multiples times, we can infer that the feature is useful," according to co-author W. Leo Smith, from the University of Kansas. "You have this whole habitat where everything that's not living at the top or bottom of the ocean or along the edges -- nearly every vertebrate living in the open water -- around 80 percent of those fish species are bioluminescent. So this tells us bioluminescence is almost a requirement for fishes to be successful."

"Many fishes proliferate species when they evolve this trait -- they differentiate, but we don't know why," Smith said. "In the ocean, there are no physical barriers to separate groups of deep-sea fishes, so why are there so many species of anglerfishes, for example? When they start using bioluminescence for species recognition, they diversify into a lot more species."

To follow this line of inquiry, Smith and his co-authors are now working to identify specific genes associated with the production of bioluminescence in fishes.

Adapted by PLOS ONE from release provided by the author.

Source: PLOS