The molecular basis of color vision in colorful fish: Four Long Wave-Sensitive (LWS) opsins in guppies (Poecilia reticulata) are defined by amino acid substitutions at key functional sites

<p>Abstract</p> <p>Background</p> <p>Comparisons of functionally important changes at the molecular level in model systems have identified key adaptations driving isolation and speciation. In cichlids, for example, long wavelength-sensitive (LWS) opsins appear to play a role in mate choice and male color variation within and among species. To test the hypothesis that the evolution of elaborate coloration in male guppies (<it>Poecilia reticulata</it>) is also associated with opsin gene diversity, we sequenced long wavelength-sensitive (LWS) opsin genes in six species of the family Poeciliidae.</p> <p>Results</p> <p>Sequences of four LWS opsin genes were amplified from the guppy genome and from mRNA isolated from adult guppy eyes. Variation in expression was quantified using qPCR. Three of the four genes encode opsins predicted to be most sensitive to different wavelengths of light because they vary at key amino acid positions. This family of LWS opsin genes was produced by a diversity of duplication events. One, an intronless gene, was produced prior to the divergence of families Fundulidae and Poeciliidae. Between-gene PCR and DNA sequencing show that two of the guppy LWS opsins are linked in an inverted orientation. This inverted tandem duplication event occurred near the base of the poeciliid tree in the common ancestor of <it>Poecilia </it>and <it>Xiphophorus</it>. The fourth sequence has been uncovered only in the genus <it>Poecilia</it>. In the guppies surveyed here, this sequence is a hybrid, with the 5' end most similar to one of the tandem duplicates and the 3' end identical to the other.</p> <p>Conclusion</p> <p>Enhanced wavelength discrimination, a possible consequence of opsin gene duplication and divergence, might have been an evolutionary prerequisite for color-based sexual selection and have led to the extraordinary coloration now observed in male guppies and in many other poeciliids.</p

The molecular basis of color vision in colorful fish: Four Long Wave-Sensitive (LWS) opsins in guppies () are defined by amino acid substitutions at key functional sites-0

S designed to target all LWS loci (see methods). Two size markers (given in base-pairs) are shown to the right of the blot.<p><b>Copyright information:</b></p><p>Taken from "The molecular basis of color vision in colorful fish: Four Long Wave-Sensitive (LWS) opsins in guppies () are defined by amino acid substitutions at key functional sites"</p><p>http://www.biomedcentral.com/1471-2148/8/210</p><p>BMC Evolutionary Biology 2008;8():210-210.</p><p>Published online 18 Jul 2008</p><p>PMCID:PMC2527612.</p><p></p

The molecular basis of color vision in colorful fish: Four Long Wave-Sensitive (LWS) opsins in guppies () are defined by amino acid substitutions at key functional sites-1

the associated taxa clustered in the bootstrap re-analyses (1000 replicates) is shown. Nodes in less than 50% of the bootstrap trees were collapsed. All codon positions were included and gaps treated as missing data. There were 1101 positions in the alignment and 520 were parsimony informative. The tree was rooted with the arctic lamprey LWS gene. Duplication events marked with an asterix. Phylogenetic analyses utilized MEGA4 [] and the alignment from Additional file .<p><b>Copyright information:</b></p><p>Taken from "The molecular basis of color vision in colorful fish: Four Long Wave-Sensitive (LWS) opsins in guppies () are defined by amino acid substitutions at key functional sites"</p><p>http://www.biomedcentral.com/1471-2148/8/210</p><p>BMC Evolutionary Biology 2008;8():210-210.</p><p>Published online 18 Jul 2008</p><p>PMCID:PMC2527612.</p><p></p

The molecular basis of color vision in colorful fish: Four Long Wave-Sensitive (LWS) opsins in guppies () are defined by amino acid substitutions at key functional sites-2

Howing the averaged logarithm value of original transcript copy number is shown (with standard error bars included).<p><b>Copyright information:</b></p><p>Taken from "The molecular basis of color vision in colorful fish: Four Long Wave-Sensitive (LWS) opsins in guppies () are defined by amino acid substitutions at key functional sites"</p><p>http://www.biomedcentral.com/1471-2148/8/210</p><p>BMC Evolutionary Biology 2008;8():210-210.</p><p>Published online 18 Jul 2008</p><p>PMCID:PMC2527612.</p><p></p