Article

Opsin gene duplication and diversification in the guppy, a model for sexual selection

Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
Proceedings of the Royal Society B: Biological Sciences (Impact Factor: 5.05). 02/2007; 274(1606):33-42. DOI: 10.1098/rspb.2006.3707
Source: PubMed

ABSTRACT

Identification of genes that control variation in adaptive characters is a prerequisite for understanding the processes that drive sexual and natural selection. Male coloration and female colour perception play important roles in mate choice in the guppy (Poecilia reticulata), a model organism for studies of natural and sexual selection. We examined a potential source for the known variation in colour perception, by analysing genomic and complementary DNA sequences of genes that code for visual pigment proteins. We find high sequence variability, both within and between populations, and expanded copy number for long-wave sensitive (LWS) opsin genes. Alleles with non-synonymous changes that suggest dissimilar spectral tuning properties occur in the same population and even in the same individual, and the high frequency of non-synonymous substitutions argues for diversifying selection acting on these proteins. Therefore, variability in tuning amino acids is partitioned within individuals and populations of the guppy, in contrast to variability for LWS at higher taxonomic levels in cichlids, a second model system for differentiation owing to sexual selection. Since opsin variability parallels the extreme male colour polymorphism within guppy populations, we suggest that mate choice has been a major factor driving the coevolution of opsins and male ornaments in this species.

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Available from: Detlef Weigel, Sep 16, 2014
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    • "The perception of visual signals is determined by two components: the physical characteristics of a habitat and the sensory properties of a receiver (Endler 1990); therefore , a change in one of these two components tends to drive the development of substitute signals in response to variable habitats (Chunco et al. 2007; Endler 1980), which has been demonstrated by several studies (Dalton et al. 2010; Fuller et al. 2005; Gray et al. 2008; Hoffmann et al. 2007). Based on the observation that the two aforementioned and closely related bitterlings exhibit distinct nuptial colorations, it is hypothesized that the differences in their nuptial colorations may be related to variations in photic properties of its habitats and/or spectral sensitivities of the fish. "

    Full-text · Dataset · Sep 2015
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    • "The perception of visual signals is determined by two components: the physical characteristics of a habitat and the sensory properties of a receiver (Endler 1990); therefore , a change in one of these two components tends to drive the development of substitute signals in response to variable habitats (Chunco et al. 2007; Endler 1980), which has been demonstrated by several studies (Dalton et al. 2010; Fuller et al. 2005; Gray et al. 2008; Hoffmann et al. 2007). Based on the observation that the two aforementioned and closely related bitterlings exhibit distinct nuptial colorations, it is hypothesized that the differences in their nuptial colorations may be related to variations in photic properties of its habitats and/or spectral sensitivities of the fish. "
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    ABSTRACT: Vision, an important sensory modality of many animals, exhibits plasticity in that it adapts to environmental conditions to maintain its sensory efficiency. Nuptial coloration is used to attract mates and hence should be tightly coupled to vision. In Taiwan, two closely related bitterlings (Paratanakia himantegus himantegus and Paratanakia himantegus chii) with different male nuptial colorations reside in different habitats. We compared the visual spectral sensitivities of these subspecies with the ambient light spectra of their habitats to determine whether their visual abilities correspond with photic parameters and correlate with nuptial colorations. The electroretinogram (ERG) results revealed that the relative spectral sensitivity of P. h. himantegus was higher at 670 nm, but lower at 370 nm, than the sensitivity of P. h. chii. Both bitterlings could perceive and reflect UV light, but the UV reflection patterns differed between genders. Furthermore, the relative irradiance intensity of the light spectra in the habitat of P. h. himantegus was higher at long wavelengths (480–700 nm), but lower at short wavelengths (350–450 nm), than the light spectra in the habitats of P. h. chii. Two phylogenetically closely related bitterlings, P. h. himantegus and P. h. chii, dwell in different waters and exhibit different nuptial colorations and spectral sensitivities, which may be the results of speciation by sensory drive. Sensory ability and signal diversity accommodating photic environment may promote diversity of bitterling fishes. UV light was demonstrated to be a possible component of bitterling visual communication. The UV cue may assist bitterlings in gender identification.
    Full-text · Article · May 2015 · Zoological studies
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    • "Endler (1992) suggested that this sensory variation could contribute to differences in female preference. Hoffmann et al. (2007) first reported several different sequences belonging to the M/LWS and other types of opsin genes, and this genetic variation was present both within and between individuals of guppies. Multiple M/LWS sequences were also reported independently by Weadick and Chang (2007). "
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    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.
    Full-text · Article · Nov 2014 · Heredity
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