Scientists have decoded the DNA of a celebrated \"living fossil\" fish, gaining new insights into how today's mammals, amphibians, reptiles and birds evolved from a fish ancestor. <\/p>\n
The African coelacanth (SEE-lah-kanth) is closely related to the fish lineage that started to move toward a major evolutionary transformation, living on land And it hasn't changed much from its ancestors of even 300 million years ago, researchers said. <\/p>\n
At one time, scientists thought coelacanths died out some 70 million years ago. But in a startling discovery in 1938, a South African fish trawler caught a living specimen. Its close resemblance to its ancient ancestors earned it the \"living fossil\" nickname. <\/p>\n
And in line with that, analysis shows its genes have been remarkably slow to change, an international team of researchers reported Wednesday in the journal Nature. <\/p>\n
Maybe that's because the sea caves where the coelacanth lives provide such a stable environment, said Kerstin Lindblad-Toh, senior author of the paper and a gene expert at the Broad Institute in Cambridge, Mass. <\/p>\n
Modern coelacanths make up two endangered species that live off the east coast of Africa and off Indonesia. They grow to more than 5 feet long and have fleshy fins. <\/p>\n
The coelacanth's DNA code, called its genome, is slightly smaller than a human's. Using it as a starting point, the researchers found evidence of changes in genes and in gene-controlling \"switches\" that evidently aided the move onto land. They involve such things as sense of smell, the immune system and limb development. <\/p>\n
Further study of the genome may give more insights into the transition to living on land, they said. Their analysis concluded that a different creature, the lungfish, is the closest living fish relative of animals with limbs, like mammals, but they said the lungfish genome is too big to decode. <\/p>\n
The water-to-land transition took tens of millions of years, with limbs developing in primarily aquatic animals as long as nearly 400 million years ago, by some accounts, and a true switchover to life on land by maybe 340 million years ago, said researcher Ted Daeschler. <\/p>\n
Daeschler, curator of vertebrate zoology at the Academy of Natural Sciences of Drexel University in Philadelphia, who didn't participate in the new work, said genome research provides a way to tackle some previously unanswerable questions in evolution. <\/p>\n
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More here: Scientists have decoded the DNA of a celebrated \"living fossil\" fish, gaining new insights into how today's mammals, amphibians, reptiles and birds evolved from a fish ancestor. The African coelacanth (SEE-lah-kanth) is closely related to the fish lineage that started to move toward a major evolutionary transformation, living on land And it hasn't changed much from its ancestors of even 300 million years ago, researchers said Continue reading
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