title: Divergent selection for opsin gene variation in guppy (Poecilia reticulata) populations of Trinidad and Tobago.
abstract: The guppy is known to exhibit remarkable interindividual variations in spectral sensitivity of middle to long wavelength-sensitive (M/LWS) cone photoreceptor cells. The guppy has four M/LWS-type opsin genes (LWS-1, LWS-2, LWS-3 and LWS-4) that are considered to be responsible for this sensory variation. However, the allelic variation of the opsin genes, particularly in terms of their absorption spectrum, has not been explored in wild populations. Thus, we examined nucleotide variations in the four M/LWS opsin genes as well as blue-sensitive SWS2-B and ultraviolet-sensitive SWS1 opsin genes for comparison and seven non-opsin nuclear loci as reference genes in 10 guppy populations from various light environments in Trinidad and Tobago. For the first time, we discovered a potential spectral variation (180 Ser/Ala) in LWS-1 that differed at an amino acid site known to affect the absorption spectra of opsins. Based on a coalescent simulation of the nucleotide variation of the reference genes, we showed that the interpopulation genetic differentiation of two opsin genes was significantly larger than the neutral expectation. Furthermore, this genetic differentiation was significantly related to differences in dissolved oxygen (DO) level, and it was not explained by the spatial distance between populations. The DO levels are correlated with eutrophication that possibly affects the color of aquatic environments. These results suggest that the population diversity of opsin genes is significantly driven by natural selection and that the guppy could adapt to various light environments through color vision changes.
authors.affiliation: Department of Ecology and Evolutionary Biology, Graduate School of Science, Tohoku University, Sendai, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Tezuka
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kasagi
authors.affiliation: School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, UK.
authors.forename: C
authors.initials: C
authors.lastname: van Oosterhout
authors.affiliation: School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, UK.
authors.forename: M
authors.initials: M
authors.lastname: McMullan
authors.affiliation: Department of Ecology and Evolutionary Biology, Graduate School of Science, Tohoku University, Sendai, Japan.
authors.forename: W M
authors.identifier: 0000000247187605
authors.initials: WM
authors.lastname: Iwasaki
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Japan.
authors.forename: D
authors.initials: D
authors.lastname: Kasai
authors.affiliation: Department of Evolutionary Studies of Biosystems, Graduate University for Advanced Studies (Sokendai), Hayama, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yamamichi
authors.affiliation: Department of Evolutionary Studies of Biosystems, Graduate University for Advanced Studies (Sokendai), Hayama, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Innan
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kawamura
authors.affiliation: Department of Ecology and Evolutionary Biology, Graduate School of Science, Tohoku University, Sendai, Japan.
authors.forename: M
authors.identifier: 0000000187165438
authors.initials: M
authors.lastname: Kawata
mesh_terms: D000818:Animals; D004777:Environment; D005260:Female; D029941:Fish Proteins / Q000235:genetics*; D005787:Gene Frequency; D014644:Genetic Variation; D005828:Genetics, Population; D008027:Light; D015810:Linkage Disequilibrium; D008297:Male; D055355:Opsins / Q000235:genetics*; D011036:Poecilia / Q000235:genetics*; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D014300:Trinidad and Tobago
chemical_list: D029941:Fish Proteins; D055355:Opsins