Full metadata
Title
The costs and consequences of iridescent coloration in Anna's hummingbirds (Calypte anna)
Description
Colorful ornaments in animals often serve as sexually selected signals of quality. While pigment-based colors are well-studied in these regards, structural colors that result from the interaction of light with photonic nanostructures are comparatively understudied in terms of their consequences in social contexts, their costs of production, and even the best way to measure them. Iridescent colors are some of the most brilliant and conspicuous colors in nature, and I studied the measurement, condition-dependence, and signaling role of iridescence in Anna's hummingbirds (Calypte anna). While most animal colors are easily quantified using well-established spectrophotometric techniques, the unique characteristics of iridescent colors present challenges to measurement and opportunities to quantify novel color metrics. I designed and tested an apparatus for careful control and measurement of viewing geometry and highly repeatable measurements. These measurements could be used to accurately characterize individual variation in iridescent Anna's hummingbirds to examine their condition-dependence and signaling role. Next, I examined the literature published to date for evidence of condition-dependence of structural colors in birds. Using meta-analyses, I found that structural colors of all three types - white, ultra-violet/blue, and iridescence - are significantly condition-dependent, meaning that they can convey information about quality to conspecifics. I then investigated whether iridescent colors were condition-dependent in Anna's hummingbirds both in a field correlational study and in an experimental study. Throughout the year, I found that iridescent feathers in both male and female Anna's hummingbirds become less brilliant as they age. Color was not correlated with body condition in any age/sex group. However, iridescent coloration in male Anna's hummingbirds was significantly affected by experimental protein in the diet during feather growth, indicating that iridescent color may signal diet quality. Finally, I examined how iridescent colors were used to mediate social competitions in male and female Anna's hummingbirds. Surprisingly, males that were less colorful won significantly more contests than more colorful males, and colorful males received more aggression. Less colorful males may be attempting to drive away colorful neighbors that may be preferred mates. Female iridescent ornament size and color was highly variable, but did not influence contest outcomes or aggression.
Date Created
2012
Contributors
- Meadows, Melissa (Author)
- McGraw, Kevin J. (Thesis advisor)
- Rutowski, Ronald L (Committee member)
- Sabo, John L (Committee member)
- Alcock, John (Committee member)
- Deviche, Pierre (Committee member)
- Arizona State University (Publisher)
Topical Subject
Resource Type
Extent
xvi, 229 p. : ill. (some col.)
Language
eng
Copyright Statement
In Copyright
Primary Member of
Peer-reviewed
No
Open Access
No
Handle
https://hdl.handle.net/2286/R.I.14990
Statement of Responsibility
by Melissa Meadows
Description Source
Viewed on June 25, 2013
Level of coding
full
Note
thesis
Partial requirement for: Ph. D., Arizona State University, 2012
bibliography
Includes bibliographical references (p. 108-113)
Field of study: Biology
System Created
- 2012-08-24 06:27:40
System Modified
- 2021-08-30 01:46:13
- 3 years 2 months ago
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