Saturday, November 16, 2013

Coelacanths might be monogamous, to the surprise of researchers

by Cynthia McKelvey
They evaded humans for millions of years and live very private lives. The hulking, fleshy-finned fish known as the coelacanth has beguiled scientists for generations. But the coelacanth mystique that enchants researchers also makes it difficult to study. Researchers recently revealed in Nature Communications one startling aspect of the coelacanth lifestyle: they might be monogamous.
Presumed extinct for over 60 million years, the coelacanth (SEE-lah-kanth) was known only in fossil form until a fisherman caught a live one in 1938 near South Africa. Recently, scientists have found populations of dozens of coelacanths nestled in caves hundreds of meters deep in the Indian Ocean near Kenya, Tanzania and the Comoros Islands.
Monogamy poses a risk to coelacanths in part because of the onerous three-year-long pregnancies in females. The babies are fully developed when they’re born, but the mother sacrifices a lot of energy and is more vulnerable to predators while she carries her young. If one male with a bad set of genes sires the brood, all the offspring can suffer—and those three years might be wasted.
The study’s authors expected coelacanth females to find multiple mates to ensure that at least some offspring get a good set of genes. They conducted genetic paternity tests on the 49 total offspring of two preserved pregnant coelacanths. Analysis showed that each coelacanth chose only one male to sire her brood.

Because coelacanths are endangered, scientists can only examine dead specimens that fishermen accidentally catch in trawls. Pregnant females are especially rare: one fish was caught near Mozambique in 1991, and another near Zanzibar in 2009. 


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