Washington, Oct 5 (ANI): A study into the muscle development of several different fish has provided insights into the genetic leap that set the scene for the evolution of hind legs in terrestrial animals.
This innovation gave rise to the tetrapods-four-legged creatures, and our distant ancestors-that made the first small steps on land some 400 million years ago.
Scientists have long known that ancient lungfish species are the ancestors of the tetrapods. These fish could survive on land, breathing air and using their pelvic fins to propel themselves.
A team of Australian scientists used fish living today to trace the evolution of pelvic fin muscles to find out how the load-bearing hind limbs of the tetrapods evolved.
They studied "primitive" cartilaginous fish-Australia's bamboo shark and its cousin, the elephant shark-as well as three bony fishes-the Australian lungfish, the zebrafish and the American paddlefish.
"We examined the way the different fish species generated the muscles of their pelvic fins, which are the evolutionary forerunners of the hind limbs," said lead researcher Professor Peter Currie, of the Australian Regenerative Medicine Institute at Monash University.
They found that the bony fish had a different mechanism of pelvic fin muscle formation from that of the cartilaginous fish, a mechanism that was a stepping stone to the evolution of tetrapod physiology.
"Humans are just modified fish. The genome of fish is not vastly different from our own," said Prof. Currie.
"We have shown that the mechanism of pelvic muscle formation in bony fish is transitional between that in sharks and in our tetrapod ancestors," he added.
The study was reported October 4 in online, open access journal PLoS Biology. (ANI)
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