A recent study has unveiled that the King demoiselle (Chrysiptera rex) is actually three different species that recently diverged from each other.  (picture)

“This work, along with others, is starting to show that there is a lot more biodiversity in the oceans then we previously thought,” said Joshua Drew, a marine conservation biologist at the Field Museum of Natural History in Chicago and a member of the demoiselle study. “We really are in a situation where we are losing things before we even know they exist.”

The King demoiselle comes in a wide range of colours and patterns, but this alone is not enough to consider it several species. There are plenty of examples of fish that look very dissimilar from each other while still belonging to the same species.

However, what Dews’ colleagues discovered while doing field research in Southeast Asia was that the differences in appearance seemed to be linked to distinct geographical regions. In order to find out more, they decided to ship about a dozen King demoiselle samples to Drew, collected from three separate populations in Indonesia, the Philippines and the South China Sea.

In his laboratory, Drew analyzed the genetic composition of the samples, focusing on three different genes – one that has evolved slowly and two that have changed quickly over the years. What Drew found out was highly interesting: the two fast changing genes differed in the three geographical groups, but not the one slow changing one. This indicates that from an evolutionary perspective, the three groups diverged from each other quite recently.

“That means that this little fish we thought was broadly distributed has a mosaic of individual populations and each one is genetically distinct,” Drew explained. “That highlights how little we really know about how biodiversity on Earth is distributed.”

Earlier, scientists assumed that it was difficult for distinct populations of reef fish to form if they had small larvae easily caught by currents. It seemed reasonable to presume that larvae from many different geographical locations would intermingle with each other throughout the sea. New data, obtained from studies like the King demoiselle one, do however suggest that larvae often settle close to its point of origin.

The King demoiselle study will be published in the journal Coral Reefs.

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