File:Eye evolution.jpg: Difference between revisions

PMC3227406

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Original figure legend: General scheme of eye evolution. The first step in eye evolution is the evolution of a light receptor molecule which in all metazoa is rhodopsin. In the most ancestral metazoa, the sponges, a single Pax gene, but no opsin gene has been found. In the cubozoan jellyfish Tripedalia, a unicellular photoreceptor has been described in the larva. The adult jellyfish has complex lens eyes which form under the control of PaxB, whereas the eyes of a hydrozoan jellyfish (Cladonema) are controlled by PaxA. We propose that from the unicellular photoreceptor cell the prototypic eye postulated by Darwin originated by a first step of cellular differentiation into photoreceptor cell and pigment cell controlled by Pax6 and Mitf, respectively. From this prototype, all the more complex eye types arose monophyletically. As a mechanism, we propose intercalary evolution of progressively more genes such as lens genes into the eye developmental pathway.

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Copyright The Author(s) 2011. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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