The evolution of opsins and color vision: connecting genotype to a complex phenotype

Abstract

Este artículo fue presentado por invitación de la Red Colombiana de Biología Evolutiva (COLEVOL) y Acta Biológica Colombiana con el fin de incentivar la investigación en el área de biología evolutiva. ABSTRACTDissecting the genetic basis of adaptive traits is key to our understanding of evolutionary processes. A major and essential step in the study of evolutionary genetics is drawing link between genotype and phenotype, which depends on the difficult process of defining the phenotype at different levels, from functional to organismal. Visual pigments are a key component of the visual system and their evolution could also provide important clues on the evolution of visual sensory system in response to sexual and natural selection. As a system in which genotype can be linked to phenotype, I will use visual pigments and color vision, particularly in birds, as a case of a complex phenotype. I aim to emphasize the difficulties in drawing the genotype-phenotype relationship for complex phenotypes and to highlight the challenges of doing so for color vision. The use of vision-based receiver models to quantify animal colors and patterns is increasingly important in many fields of evolutionary research, spanning studies of mate choice, predation, camouflage and sensory ecology. Given these models impact on evolution and ecology, it is important to provide other researchers with the opportunity to better understand animal vision and the corresponding advantages and limitations of these models.Keywords: avian visual pigments, color vision, complex phenotypes, genotype-phenotype, opsins. RESUMENEntender la base genética de los rasgos adaptativos es un paso crítico en el estudio de los procesos evolutivos. Para estudiar la conexión entre genotipo y fenotipo es importante definir el fenotipo a diferentes niveles: desde las proteínas que se construyen con base en un gen, hasta las características finales presentes en un organismo. Las opsinas y los fotopigmentos son elementos primordiales de la visión y entender cómo han evolucionado es fundamental en el estudio de la visión en los animales como un caracter derivado de selección natural o sexual. Este artículo se enfoca en este sistema, en el que se pueden conectar genotipo y fenotipo, como ejemplo de fenotipo complejo para ilustrar las dificultades de establecer una relación clara entre genotipo y fenotipo. Adicionalmente, este artículo tiene como objetivo discutir el funcionamiento del sistema de fotorrecepción, con énfasis particular en las aves, con el fin de enumerar varios factores que deben ser tenidos en cuenta para predecir cambios en la visión a partir del estudio de los fotopigmentos. Dado que los modelos basados en la visión de aves son cada vez más usados en diversas áreas de la biología evolutiva tales como: selección de pareja, depredación y camuflaje; se hace relevante entender los fundamentos y limitaciones de estos modelos. Por esta razón, en este artículo discuto los detalles y aspectos prácticos del uso de los modelos de visión existentes para aves, con el...

Opsin expression predicts male nuptial color in threespine stickleback

“…Trait correlations such as these are an essential feature of many models of sexual selection and signal evolution and can help explain the apparent concerted evolution of signal and preference in nature. Our results highlight the potential importance of opsin expression variation as a substrate for female preference evolution (Bloch, , ; Lind et al., ; Price, ; Sandkam et al., ). Finally, these results suggest a potential sensory mechanism that could facilitate the maintenance of variation in male nuptial color via negative frequency‐dependent selection (Bolnick et al.…”

“…Furthermore, visual modeling results and path analyses suggest that this correlation is not an artifact of shared tuning to the optical microhabitat, which varies with nest depth. These results provide further evidence for signal-preference/sensitivity correlations, as well as highlight the potential importance of opsin expression variation as a substrate for both female preference evolution (Bakker, 1993;Bloch, 2015Bloch, , 2016Lind, Henze, & Osorio, 2017;Price, 2017;Rick et al, 2011;Sandkam et al, 2015) and negative frequencydependent selection via male-male competition (Bolnick et al 2016).…”

Multiple mechanisms of photoreceptor spectral tuning following loss of UV color vision inHeliconiusbutterflies

“…Opsin proteins covalently bond a vitamin A-derived chromophore to make rhodopsin, the visual pigment responsible for detection of light in animal photoreceptor cells (Palczewski et al, 2000). Among opsin duplicates, amino acid substitutions that interact with the chromophore may shift the probability that a particular rhodopsin absorbs a photon of light at a given wavelength (Arshavsky et al, 2002; Bloch, 2016; Shichida and Matsuyama, 2009). Other ways of modifying a photoreceptor neuron’s sensitivity to light include the addition of photostable filtering pigments and co-expression of multiple opsins in a single cell (Arikawa et al, 2003; K. Arikawa et al, 1999; Kentaro Arikawa et al, 1999; Dalton et al, 2014; Knott et al, 2010; Satoh et al, 2017; Vöcking et al, 2017; Wakakuwa et al, 2004).…”

Molecular Mechanisms Underlying Vertebrate Adaptive Evolution: A Systematic Review

“…Lighting conditions vary considerably across environments, thus successful colonization of new environments requires adaptation of visual systems. Ecological factors shape visual sensitivities and have an impact on the molecular mechanisms that drive the adaptive evolution of visual structures and/or regulatory mechanisms in vertebrates [6,[14][15][16][17]. Adaptation to a novel lighting environment is a complex process that requires changes in lens transmittance and retinal cell structure (i.e., chromatophore ratios and opsin gene expression) [14,15,18,19].…”