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Mechanisms and Evolution of Iridescent Feather Colors in Birds

Eliason, Chad M
http://rave.ohiolink.edu/etdc/view?acc_num=akron1407426971

Abstract Details

2014, Doctor of Philosophy, University of Akron, Integrated Bioscience.
A longstanding question in biology is why phenotypic diversity is unevenly distributed across the tree of life. Such differences can be caused by both extrinsic (e.g., natural selection) and intrinsic factors (e.g., how a trait functions). Despite numerous examples of diversification in form and function of complex biomechanical traits, we know relatively little about these processes in ornamental traits. Diverse ornamental feather colors in birds can be produced either by absorption (pigment-based colors) or scattering of light by feather nanostructures (structural colors). Because structural colors are deterministically related to the nanostructures that produce them, they are excellent systems to study form-function relationships and diversity of ornamental traits. In my dissertation I combine methods from physics and evolutionary biology to understand how proximate mechanisms explaining color (coherent light scattering) explain patterns of color diversity using iridescent feathers as a model system. Specifically, I ask two fundamental questions, one proximate and one ultimate, about iridescent colors: i) How are iridescent colors produced? and ii) What are the implications of how iridescent traits function for how they evolve? To tackle these questions, I sampled a nanostructurally diverse range of species, quantified their nanostructures with TEM and optical microscopy, experimentally tested the roles of different nanostructural traits in producing color by modifying them at the nanometer scale with FIB milling or humidity changes, and linked form and function with optical modeling. I then used simulation-based approaches and large-scale comparative analysis of color diversity to explore evolutionary consequences of functionally modular nanostructures in feathers. Together, my results suggest that morphological novelties in birds have, at least in part, allowed birds to achieve their vast morphological and colour diversity, and the way a color is produced has implications for how it evolves. The results of this research better our understanding of why bird colors are so diverse, generate testable hypotheses about the functions and evolution of bird colors, and demonstrate previously unforeseen costs of iridescent plumages that may help to explain the evolution and distribution of iridescence in birds.
Matthew Shawkey, Dr. (Advisor)
Blackledge Todd, Dr. (Committee Member)
Luettmer-Strathmann Jutta, Dr. (Committee Member)
Dhinojwala Ali, Dr. (Committee Member)
Doucet Stephanie, Dr. (Committee Member)
182 p.
Biology; Physics
structural color; photonic crystals; materials science; hydrophobicity; trade offs; modularity; constraint; phenotypic evolution

Recommended Citations

Citations

  • Eliason, C. M. (2014). Mechanisms and Evolution of Iridescent Feather Colors in Birds [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1407426971

    APA Style (7th edition)

  • Eliason, Chad. Mechanisms and Evolution of Iridescent Feather Colors in Birds. 2014. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1407426971.

    MLA Style (8th edition)

  • Eliason, Chad. "Mechanisms and Evolution of Iridescent Feather Colors in Birds." Doctoral dissertation, University of Akron, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1407426971

    Chicago Manual of Style (17th edition)

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© 2014, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.