Molecular Evolution and Functional Characterization of the Visual Pigment Proteins of the Great Bowerbird (Chlamydera nuchalis) and Other Vertebrates
type: CreativeWork
description: Visual pigments are light sensitive receptors in the eye that form the basis of sensory visual transduction. This thesis presents three studies that explore visual pigment proteins in vertebrates using a number of computational and experimental methods in an evolutionary framework. The objective is not only to identify, but also to experimentally investigate the functional consequences of genetic variation in vertebrate visual pigments. The focus is on great bowerbirds (Chlamydera nuchalis), which are a model system in visual ecology due to their spectacular behaviour of building and decorating courtship bowers. There are 4 chapters: Chapter 1 introduces background information on visual pigments and vision in birds. Among visual pigment types, the short-wavelength-sensitive (SWS1) pigments have garnered particular interest due to the broad spectral range among vertebrates and the importance of UV signals in communication. Chapter 2 investigates the evolutionary history of SWS1 in vertebrates with a view toward its utility as a phylogenetic marker. Chapter 3 investigates SWS1 evolution and short-wavelength vision in birds, with particular focus on C. nuchalis and its SWS1. The evolution of spectral tuning mechanisms mediating UV/violet vision in passerines and parrots is elucidated in this chapter using site-directed mutagenesis, protein expression, and phylogenetic recreation of ancestral opsins. While cone opsins mediate colour vision in bright light, the rhodopsin visual pigment contained in rod photoreceptors is critical for dim light vision. Detailed characterization of rhodopsin function has only been conducted on a few model systems. Chapter 4 examines C. nuchalis RH1 using a number of functional assays in addition to absorbance spectra, including hydroxylamine sensitivity and the rate of retinal release. This chapter includes an investigation into the role of amino acid mutations typical of dim-light adapted vertebrates, D83N and A292S, in regulating function…
abstract: Visual pigments are light sensitive receptors in the eye that form the basis of sensory visual transduction. This thesis presents three studies that explore visual pigment proteins in vertebrates using a number of computational and experimental methods in an evolutionary framework. The objective is not only to identify, but also to experimentally investigate the functional consequences of genetic variation in vertebrate visual pigments. The focus is on great bowerbirds (Chlamydera nuchalis), which are a model system in visual ecology due to their spectacular behaviour of building and decorating courtship bowers. There are 4 chapters: Chapter 1 introduces background information on visual pigments and vision in birds. Among visual pigment types, the short-wavelength-sensitive (SWS1) pigments have garnered particular interest due to the broad spectral range among vertebrates and the importance of UV signals in communication. Chapter 2 investigates the evolutionary history of SWS1 in vertebrates with a view toward its utility as a phylogenetic marker. Chapter 3 investigates SWS1 evolution and short-wavelength vision in birds, with particular focus on C. nuchalis and its SWS1. The evolution of spectral tuning mechanisms mediating UV/violet vision in passerines and parrots is elucidated in this chapter using site-directed mutagenesis, protein expression, and phylogenetic recreation of ancestral opsins. While cone opsins mediate colour vision in bright light, the rhodopsin visual pigment contained in rod photoreceptors is critical for dim light vision. Detailed characterization of rhodopsin function has only been conducted on a few model systems. Chapter 4 examines C. nuchalis RH1 using a number of functional assays in addition to absorbance spectra, including hydroxylamine sensitivity and the rate of retinal release. This chapter includes an investigation into the role of amino acid mutations typical of dim-light adapted vertebrates, D83N and A292S, in regulating function…
author: Hazel, Ilke van
language: en_ca
keywords: bowerbird, visual pigments, opsin, vertebrate phylogenetics, molecular marker, avian vision, visual behaviour, adaptation, mutagenesis, protein expression, short wavelength sensitive 1, SWS1, spectral tuning, evolution, ancestral sequence reconstruction, maximum likelihood, rhodopsin, rod opsin, RH1, retinal release, photoactivation cycle, dim light adaptation, molecular evolution, PAML
license: http://creativecommons.org/licenses/by-sa/2.5/ca/
date published: 2012-11
date modified: 2026-07-27T21:27:58Z
provider: University of Toronto
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Toronto

PropertyValue
property ID: Handle
value: http://hdl.handle.net/1807/43401