In my dissertation I focused on several topics, two of which involve islands and another that follows logically from my work on islands: contemporary evolution and cryptic introductions, variation in island plumage coloration, and variation in plumage coloration within a lineage. I chose to work with the eastern bluebird (Sialia sialis) because it has an isolated island subspecies long thought to be endemic to Bermuda based upon striking plumage differences. In my first chapter I used microsatellite data to explore the origin and current status of this island population. Through my analysis I determined that the Bermuda subspecies represents one of the few known cases of a vertebrate cryptic invader that was likely introduced by humans approximately 400 years ago. Oceanic islands have a relatively recent history of human colonization and in the absence of paleontological or molecular evidence it should not be assumed that island species are native. In both my second and third chapters I used avian perceptual modeling to deconstruct blue plumage coloration into four components (hue, chroma, percent UV, and brightness). In my second chapter, I used feathers from live birds to detail how color varied between island and mainland populations. I found significant differences in hue (shorter wavelengths) and increased brightness on Bermuda; showing rapid change over a short time frame. My work suggests that we need to define better what constitutes a ‘native’ species, especially in cases such as the eastern bluebird in Bermuda where there has been sufficient divergence in morphology to be classified as a subspecies. My third chapter used museum specimens across the bluebird range to attribute specific color components to detectable differences between subspecies. Differences in percent UV and chroma accounted for most intraspecific variation. These components are thought to be condition dependent and may signify the importance of individual-level variation in phenotypic evolution. Furthermore, individual components did not vary in a coordinated manner, implying modularity between the mechanisms controlling color expression.
Subject (authority = RUETD)
Topic
Ecology and Evolution
Subject (authority = ETD-LCSH)
Topic
Eastern bluebird--Color
Subject (authority = ETD-LCSH)
Topic
Eastern bluebird--Bermuda Islands
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TitleInfo
Title
Rutgers University Electronic Theses and Dissertations
Identifier (type = RULIB)
ETD
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TitleInfo
Title
Graduate School - New Brunswick Electronic Theses and Dissertations
Rutgers University. Graduate School - New Brunswick
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License
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Author Agreement License
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I hereby grant to the Rutgers University Libraries and to my school the non-exclusive right to archive, reproduce and distribute my thesis or dissertation, in whole or in part, and/or my abstract, in whole or in part, in and from an electronic format, subject to the release date subsequently stipulated in this submittal form and approved by my school. I represent and stipulate that the thesis or dissertation and its abstract are my original work, that they do not infringe or violate any rights of others, and that I make these grants as the sole owner of the rights to my thesis or dissertation and its abstract. I represent that I have obtained written permissions, when necessary, from the owner(s) of each third party copyrighted matter to be included in my thesis or dissertation and will supply copies of such upon request by my school. I acknowledge that RU ETD and my school will not distribute my thesis or dissertation or its abstract if, in their reasonable judgment, they believe all such rights have not been secured. I acknowledge that I retain ownership rights to the copyright of my work. I also retain the right to use all or part of this thesis or dissertation in future works, such as articles or books.