October 30, 2012
Eye Opening Study Sheds Light On Vision Evolution
April Flowers for redOrbit.com - Your Universe Online
Opsins are conjugated protein enzymes. These enzymes are components of the visual pigments that catch photons of light in the eyes of almost every animal from fruit flies to humans.
Partially due to inconsistent reports of phylogenetic relationships among the earliest opsin-possessing animals, there is a hot debate about the evolutionary origins of vision.
Pisani and his colleagues at NUI Maynooth performed computational analysis to test every hypothesis of opsin evolution that has been proposed to date, incorporating all available genomic information from all relevant animal lineages. This includes a newly sequenced group of sponges, called Oscarella carmela, and the Cnidarians, which are a group of animals thought to have possessed the world's earliest eyes.
A timeline was developed using this information, with an opsin ancestor common to all groups appearing some 700 million years ago. Although this opsin was considered blind, over the 11 million years it underwent key genetic changes that conveyed the ability to detect light.
Dr Pisani said, "The great relevance of our study is that we traced the earliest origin of vision and we found that it originated only once in animals. This is an astonishing discovery because it implies that our study uncovered, in consequence, how and when vision evolved in humans."