Guppies exhibit color based sexual dimorphism and females generally prefer the most
colorful males. It has also recently been found that guppies possess a large opsin
repertoire. As opsins are the receptors responsible for color vision, this ten gene
repertoire might have contributed to the evolution of extravagant male coloration in this
species. My study starts by characterizing the opsin repertoire of Jenynsia onca, a noncolorful
relative of the guppy belonging to the family Anablepidae (sister group to
Poeciliidae, of which the guppy is a member). A PCR based survey indicated that J. onca
had a very similar opsin repertoire to the guppy; J. onca had nine genes including
orthologs of all but one of the guppy opsins. To gain further insight into the origin of the
guppy repertoire, a bioinformatics based survey of ray-finned fish opsins was undertaken.
This revealed that large opsin repertoires are common in ray-finned fish and are the
product of gene duplication events, spanning the age of the taxon Teleostei. Given that
the large opsin repertoire of the guppy did not appear to be perfectly correlated with the
evolution of color based sexual selection in this lineage, I turned to investigating the
expression of this opsin repertoire. In situ hybridization was used to characterize the
pattern of opsin expression across the surface of the retina of adult male and female
guppies. In situ hybridization demonstrated that most opsin genes had distinct expression
profiles. These expression patterns also indicated that sensitivity and discrimination in the
dorsal retina might differ from the ventral retina; the ventral retina appears to be tuned to
middle-wavelength light (green), while the dorsal retina is predicted to have exceptional
wavelength discriminatory ability and broad spectral sensitivity. This expression data was
then used to evaluate models of sexual selection in the context of the predicted visual
capacity of the guppy. / Graduate
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/3654 |
| Date | 03 November 2011 |
| Creators | Rennison, Diana Jessie |
| Contributors | Taylor, John Stewart |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | Available to the World Wide Web |
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