title: Euarchontan Opsin Variation Brings New Focus to Primate Origins.
abstract: Debate on the adaptive origins of primates has long focused on the functional ecology of the primate visual system. For example, it is hypothesized that variable expression of short- (SWS1) and middle-to-long-wavelength sensitive (M/LWS) opsins, which confer color vision, can be used to infer ancestral activity patterns and therefore selective ecological pressures. A problem with this approach is that opsin gene variation is incompletely known in the grandorder Euarchonta, that is, the orders Scandentia (treeshrews), Dermoptera (colugos), and Primates. The ancestral state of primate color vision is therefore uncertain. Here, we report on the genes (OPN1SW and OPN1LW) that encode SWS1 and M/LWS opsins in seven species of treeshrew, including the sole nocturnal scandentian Ptilocercus lowii. In addition, we examined the opsin genes of the Central American woolly opossum (Caluromys derbianus), an enduring ecological analogue in the debate on primate origins. Our results indicate: 1) retention of ultraviolet (UV) visual sensitivity in C. derbianus and a shift from UV to blue spectral sensitivities at the base of Euarchonta; 2) ancient pseudogenization of OPN1SW in the ancestors of P. lowii, but a signature of purifying selection in those of C. derbianus; and, 3) the absence of OPN1LW polymorphism among diurnal treeshrews. These findings suggest functional variation in the color vision of nocturnal mammals and a distinctive visual ecology of early primates, perhaps one that demanded greater spatial resolution under light levels that could support cone-mediated color discrimination.
authors.affiliation: Department of Anthropology, Dartmouth College, Hanover, NH Department of Anthropology and Archaeology, and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB amanda.melin@ucalgary.ca nathaniel.j.dominy@dartmouth.edu.
authors.forename: Amanda D
authors.initials: AD
authors.lastname: Melin
authors.affiliation: Environmental Futures Research Institute, Griffith University, Brisbane, QLD, Australia.
authors.forename: Konstans
authors.initials: K
authors.lastname: Wells
authors.affiliation: Department of Biological Sciences, Class of 1978 Life Sciences Center, Dartmouth College, Hanover, NH Department of Evolutionary Anthropology, Duke University.
authors.forename: Gillian L
authors.initials: GL
authors.lastname: Moritz
authors.affiliation: Departments of Anthropology and Biology, Pennsylvania State University School of Life Sciences, Gibbet Hill Campus, University of Warwick, Coventry, United Kingdom.
authors.forename: Logan
authors.initials: L
authors.lastname: Kistler
authors.affiliation: Department of Anthropology and Archaeology, and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB Department of Anthropology, Washington University in St. Louis.
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Orkin
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Timm
authors.affiliation: Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia.
authors.forename: Henry
authors.initials: H
authors.lastname: Bernard
authors.affiliation: Sabah Parks, Lot 45 & 46 KK Times Square Coastal Highway, Kota Kinabalu, Sabah, Malaysia.
authors.forename: Maklarin B
authors.initials: MB
authors.lastname: Lakim
authors.affiliation: Departments of Anthropology and Biology, Pennsylvania State University.
authors.forename: George H
authors.initials: GH
authors.lastname: Perry
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Japan.
authors.forename: Shoji
authors.initials: S
authors.lastname: Kawamura
authors.affiliation: Department of Anthropology, Dartmouth College, Hanover, NH Department of Biological Sciences, Class of 1978 Life Sciences Center, Dartmouth College, Hanover, NH amanda.melin@ucalgary.ca nathaniel.j.dominy@dartmouth.edu.
authors.forename: Nathaniel J
authors.initials: NJ
authors.lastname: Dominy
mesh_terms: D000818:Animals; D055253:Color Vision / Q000235:genetics*; D019143:Evolution, Molecular; D006801:Humans; D009893:Opossums / Q000235:genetics / Q000502:physiology; D055355:Opsins / Q000235:genetics*; D010802:Phylogeny; D011323:Primates / Q000235:genetics* / Q000502:physiology; D017299:Rod Opsins / Q000235:genetics; D014466:Ultraviolet Rays
chemical_list: D055355:Opsins; D017299:Rod Opsins; C095855:long-wavelength opsin; C095853:short-wavelength opsin
keywords: Caluromys; Dendrogale; Euarchonta; Ptilocercus; Tupaia; color vision; sensory ecology