Scientists have discovered that cavefish, whose eyes have got blinded while living in complete darkness over the course of evolutionary time, can regain their sight.
Washington, January 8 : Scientists have discovered that cavefish, whose eyes have got blinded while living in complete darkness over the course of evolutionary time, can regain their sight.
Writing about their findings in Current Biology, a publication of Cell Press, the researchers said that offspring of mated pairs originating from distinct cave populations regain vision in certain cases.
The new finding suggests that mutations in different genes are responsible for eye loss in separate cavefish lineages, which may not have been exposed to light for the last one million years.
"Restoration of the ability to see comes in a single generation because the populations residing in different caves are blind for different reasons-i.e., different sets of genes are non-functional in the different populations," said Richard Borowsky of New York University.
"(In the hybrids), the deficiencies in one lineage are compensated for by the good gene copies in the other lineage, and vice versa," he added.
Previous research showed that the evolutionary impairment of eye development in cavefish results from mutations at multiple gene sites, or loci.
It also showed that eye loss has evolved independently at least three times, and that at least some of the genes involved differ between the different cave populations.
"Given the large number of mutations at different loci that have accumulated in these populations, we reasoned that hybridization among independently evolved populations might restore visual function," Borowsky said.
His team finally found that while purebred cavefish are all blind, the hybrid progeny of different cave populations all had some individuals that exhibited a clear visual response.
He said that the farther apart the caves of the cavefish parents were, the more likely it was that their offspring could see.
This finding suggests that populations separated by greater distances are more distantly related, and therefore have less overlap in the genes responsible for their blindness, he said.
According to Borowsky, besides providing insights into the evolution of cavefish in particular, the findings also speak to a more general principle.
"Evolution's palette is varied. There are numerous genetic ways to accomplish the same change," he said.
ANI