"Most reef-fish larvae feed on plankton in the water column," Reece says. "Moray larvae are so simple, they can't digest plankton, so they feed on the shed exoskeleton of plankton and on plankton excrement."
"It's ironic these vicious predators start out too delicate to eat even plankton they have to eat plankton poop and work their way up," he says laughing.
Barriers in the ocean?
In biology textbooks the go-to mechanism for speciation (or the splitting of a population into two groups that no longer interbreed) is geographic isolation. One group gets separated from the other, by for example, the formation of a mountain, and then over time natural selection and genetic drift gradually remodel the two similar groups into two dissimilar ones.
The question is whether there are barriers in the ocean that play the same role in speciation as the mountain ranges do on land.
Two suspects are the Eastern Pacific Barrier and the Sunda Shelf. The Eastern Pacific Barrier is a stretch of open ocean 3000 to 5000 kilometers wide that separates the Hawaiian archipelago and the Central Pacific Islands from the Americas. "That's just too much open ocean for larvae to cross," says Reece.
The Sunda Shelf, on the other hand, is an area of relatively shallow water between the Indian Ocean and the Pacific Ocean that has been repeatedly exposed when sea levels fell during periods of extensive glaciation.
Were the undulated and yellow-edged morays on either side of these barriers distinguishable genetically?
To find out the biologists looked at selected mitochondrial and nuclear genes and asked whether there were unique alleles (variants) of these genes and whether the degree of variance was correlated with geographic separation.
They found lots of variation among the eel genes they examin
|Contact: Diana Lutz|
Washington University in St. Louis