Skip to main content
. Author manuscript; available in PMC: 2009 Feb 4.
Published in final edited form as: Brain Res. 2007 Mar 20;1192:134–150. doi: 10.1016/j.brainres.2007.03.044

Figure 2.

Figure 2

Molecular phylogeny of vertebrate photoreceptor opsin genes. Beginning with an ancestral opsin gene approximately 700 million years ago, a series of four gene duplication events with subsequent diversification produced five opsin gene families with spectral sensitivities ranging from longest (red) to shortest (ultraviolet) wavelengths: LWS/MWS, RH1, RH2, SWS2, and SWS1. The position of the branch point along the horizontal axis from left to right indicates the relative evolutionary age, from oldest to youngest, respectively. The most closely related are RH1 (rhodopsin) and RH2, which diverged approximately 500 million years ago. The LWS/MWS family is the oldest and most divergent of the five opsin gene families.