Moray eel diversification baffles researchers
Eels diversify into subspecies, but under these circumstances, why bother?
Tue, Apr 13, 2010 at 03:17 PM
Moray eels, it seems, live counter to the theories of evolution. ScienceDaily.com reports that, in one instance, seven different species of the eel were living in the same area, eating the same species of fish. Researcher Joshua Reece told ScienceDaily, "Species don't do that; if they exploit the same niche, they don't diversify, and if they diversity they don't exploit the same niche."
Reece has dedicated his research career to finding out just what's going on with these creatures. They collected samples of several moray subspecies, and found they were genetically homogenous no matter where they lived in the Indo-Pacific Ocean, a body of water covering almost two-thirds of the Earth's surface. But knowing this does not answer Reece's initial question: why did the eels bother to diversify into subspecies to start with?
ScienceDaily reports that eels are intelligent critters, known to cooperate when hunting fish in the wild, but they are also famous for acts of aggression. They tend to bite their prey (including humans) and latch on so tightly that the only way to break free is to bash the eel's skull. The article reports that Reece keeps a photograph of an injury he suffered diving with the eels. His early attempts to even collect the eels were fraught with dangerous snafus as the eels chomped through steel cans in one bite.
But the article reports that the eels, which grow into dangerous adults, begin as delicate larvae (called pelagic larva) and remain in this stage for months or even years, much longer than other species of fish. This pelagic stage typically lets fish disperse throughout the ocean, but Reece noticed that the longer a species remained as a pelagic larva, the more likely it was to be homogenous as an adult fish.
According to ScienceDaily, "moray eels ... are poor swimmers as juveniles, and adults stick to a few square meters of reef." This lengthy larval stage might explain why the eels diversify, since geographic isolation tends to lead to "speciation," according to the story. However, eels of the same species found throughout the ocean share identical genetic material, leading scientists to wonder how this could be. There are, according to the story, 150 species of moray eel in the Indo-Pacific Ocean. The article begs the question, "When and how did they form separate species if their larvae make them nearly impervious to geographic isolation?" Reece has the rest of his career to determine the answer.