Coelacanths are not ‘Living Fossils’
The capture of the first living coelacanth, a mighty ocean predator, off the coast of South Africa caused quite a stir in 1938, coming as it did roughly 65 million years after its supposed extinction.
Coelacants are lobe-finned fish that were thought to be extinct for 65 million years, until a first living specimen was discovered fortuitously in South Africa in 1938 by a South African museum curator on a local fishing trawler.
The fish later became known as a “living fossil” because its anatomy looked almost identical to the fossil record. But while the coelacanth’s body may have changed very little, researchers at the University of Toronto say its genome tells another story.
Coelacanths present several unique and intriguing features such as unpaired lobbed-fins looking much like paired fins and highly modified lungs/swim bladder.
The findings, show the dramatic effect travelling transposon DNA can have on the creation of genes and provide a glimpse into some of the forces that shaped the genome of one of the most ancient and mysterious organisms.
“Coelacanths may have evolved a bit more slowly but it is certainly not a fossil,” said Isaac Yellan, a graduate student in the Department of Molecular Genetics at the University of Toronto.
Where the genes originally came from and what they’re doing in the coelacanth may well remain a mystery. Research specimens are only occasionally pulled up by fishing boats and it took until 1998 to discover the other known living species, Latimeria menadoensis, in an Indonesian fish market.
“Our findings provide a rather striking example of this phenomenon of transposons contributing to the host genome,” said Professor Tim Hughes, a researcher in the Donnelly Centre for Cellular and Biomolecular Research at the University of Toronto.