Credit: Scott Eipper/Nature 4 You.
New research shows that the ancestors of all living snakes had better vision than today's burrowing snakes.
The first detailed analysis of gene sequence data for any species of blindsnakes was carried out by an international team of scientists.
The genes associated with bright-light vision are not present in most snakes and lizards.
They say that this shows extensive vision gene loss similar to what has been seen in burrowing mammals with reduced vision.
The hypothesis that all snakes are descended from extreme burrowers is challenged by the fact that vision genes are present in most other living snakes. The researchers say that it would be very unlikely for such genetic deficiencies to have been reversed through evolution.
One half of the oldest divergence in the snake tree is formed by scolecophidians. They comprise approximately 450 of the 3,850 currently recognized living snake species, and are likely to have been different from their living relatives more than 65 million years ago.
The small, cylindrical, burrowing snakes with reduced eyes and small mouths are called Scolecophidians.
The dark-spined blind snake and the prong-snouted blind snake are both common in southern Australia, and scientists have generated new data for them.
They compared their results with data from other species of snakes and lizards.
The data and analytical results provide clear evidence for the reduction of elements of the visual system of burrowing Scolecophidian snakes. We already knew that snakes lost vision genes and eye structures, but most of them were still retained. Most living snakes have functional copies of a large number of vision genes. Our study shows that the ancestors of all living snakes were not as extreme as the living ones.
In May 2020 a team of researchers published a study that showed the visual systems of sea snakes have undergone remarkable adaptation to life underwater for 15 million years.
Dr. Bruno Simes is the senior author on the current study and he was the leader of that research. The nature of the ancestral snake has been debated. It has been suggested that it had evolved a reduced visual system as a result of a burrowing ecology. Our research shows that the highly subterranean lives and reduced eyes of living snakes likely evolved as specialisms rather than being the retention of primitive characteristics. The loss of genes associated with bright-light and color vision is a result of convergent evolution between subterranean snakes and burrowing mammals.
The implications of the visual system of the Ancestral Snake, Genome Biology and Evolution are discussed in this information. There is a DOI: 10.093/gbe/evab253.
The news about the worse eyesight of burrowing snakes was retrieved from thephys.org on December 9.
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