Reduced opsin gene expression in a cave-dwelling fish |
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Authors: | Michael Tobler Seth W. Coleman Brian D. Perkins Gil G. Rosenthal |
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Affiliation: | 1.Department of Biology, Texas A&M University, College Station, TX 77843, USA;2.Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX 77843, USA;3.Biology Department, Gonzaga University, Spokane, WA 99208, USA;4.Centro de Investigaciones Científicas de las Huastecas ‘Aguazarca’, Calnali, Hidalgo, Mexico |
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Abstract: | Regressive evolution of structures associated with vision in cave-dwelling organisms is the focus of intense research. Most work has focused on differences between extreme visual phenotypes: sighted, surface animals and their completely blind, cave-dwelling counterparts. We suggest that troglodytic systems, comprising multiple populations that vary along a gradient of visual function, may prove critical in understanding the mechanisms underlying initial regression in visual pathways. Gene expression assays of natural and laboratory-reared populations of the Atlantic molly (Poecilia mexicana) revealed reduced opsin expression in cave-dwelling populations compared with surface-dwelling conspecifics. Our results suggest that the reduction in opsin expression in cave-dwelling populations is not phenotypically plastic but reflects a hardwired system not rescued by exposure to light during retinal ontogeny. Changes in opsin gene expression may consequently represent a first evolutionary step in the regression of eyes in cave organisms. |
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Keywords: | regressive evolution vision qPCR Poecilia mexicana Poeciliidae |
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