title: Reduced opsin gene expression in a cave-dwelling fish.
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.
authors.affiliation: Department of Biology, Texas A&M University, , College Station, TX 77843, USA. michi.tobler@gmail.com
authors.forename: Michael
authors.initials: M
authors.lastname: Tobler
authors.forename: Seth W
authors.initials: SW
authors.lastname: Coleman
authors.forename: Brian D
authors.initials: BD
authors.lastname: Perkins
authors.forename: Gil G
authors.initials: GG
authors.lastname: Rosenthal
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D005075:Biological Evolution; D017753:Ecosystem; D005786:Gene Expression Regulation / Q000502:physiology*; D007150:Immunohistochemistry; D008800:Mexico; D055355:Opsins / Q000235:genetics / Q000378:metabolism*; D011036:Poecilia / Q000235:genetics* / Q000378:metabolism; D014785:Vision, Ocular / Q000235:genetics*
chemical_list: D055355:Opsins