The researchers also say the hypothesis that modern snakes evolved from burrowers should be challenged.
One would think that as animals evolves, it would evolve to be better equipped than their ancestors. However, with the case of burrowing or blind snakes, the opposite is true, according to new research.
Researchers with the Natural History Museum and the University of Plymouth conducted genetic analysis on blind snakes from the infraorder Scolecophidia and found that seven of 12 genes that are related to bright light vision in snakes and lizards are absent in these blind snakes.
The researchers believe that this finding shows vision gene loss over millions of years of evolutionary history. That is, the vision of these reptiles have gotten progressively worse as they have evolved.
“Our data and analytical results provide clear evidence for very substantial reduction of elements of the visual system of burrowing scolecophidian snakes. We already knew that snakes lost some vision genes and eye structures during their evolution from lizards, but most were nonetheless retained,” lead author Dr. David Gower, Head of the Life Sciences Vertebrates Division at the Natural History Museum said in a statement released by the University of Plymouth. It is highly unlikely that functional copies of a large number of vision genes were lost from the ancestral snake but subsequently re-evolved in most living snakes. As a result, our study strongly suggests that the ancestor of all living snakes was unlikely to have been as extreme a burrower as living scolecophidian snakes.”
The researchers also say the hypothesis that modern snakes evolved from burrowers should be challenged because the vision genes that are lost in the scolecophidians, can be found in most modern day snakes. They believe that genetic deficiencies being reversed through evolution is also unlikely.
The complete paper, “Eye-Transcriptome and Genome-Wide Sequencing for Scolecophidia: Implications for Inferring the Visual System of the Ancestral Snake” can be read on the Genome Biology and Evolution website.