The mesopelagic zone is located between about 650 and 3,280 feet (200 and 1,000 meters) below the ocean's surface, where light levels are very low. Many species of fish that live in the mesopelagic zone have bioluminescent systems that they use to communicate and attract prey.
The researchers conducted a comparative genomic analysis of 23 species of mesopelagic fishes, including species from eight different families. They identified 14 genes that are involved in the production of light in mesopelagic fishes, and they found that these genes have undergone a number of changes that are likely responsible for the evolution of bioluminescence.
One of the most significant changes that the researchers identified was a duplication of the luciferase gene, which is responsible for producing light. This duplication event occurred independently in two different lineages of mesopelagic fishes. The researchers suggest that this duplication event may have been a key factor in the evolution of bioluminescence, as it allowed fishes to produce more light.
The researchers also found that the bioluminescent systems of mesopelagic fishes are highly diverse, even within a single species. This diversity is likely due to the fact that mesopelagic fishes live in a variety of habitats, and they use their bioluminescent systems for different purposes. For example, some species use their bioluminescent systems to attract prey, while others use them to communicate with each other.
The researchers say that their study provides new insights into the evolutionary history of bioluminescence in mesopelagic fishes. They hope that their findings will help to shed light on the ecology and adaptations of these fascinating creatures.
