eCommons

 

Multiscale Characterization of Melanosome Morphology and Melanin Deposition Patterns in Bird Feathers with Implications for Color Production and Biological Function

Access Restricted

Access to this document is restricted. Some items have been embargoed at the request of the author, but will be made publicly available after the "No Access Until" date.

During the embargo period, you may request access to the item by clicking the link to the restricted file(s) and completing the request form. If we have contact information for a Cornell author, we will contact the author and request permission to provide access. If we do not have contact information for a Cornell author, or the author denies or does not respond to our inquiry, we will not be able to provide access. For more information, review our policies for restricted content.

No Access Until

2024-09-05
Permanent Link(s)

Other Titles

Abstract

Pigmentary color is used across nature for signaling, camouflage, and protection. Consequently, the menagerie of colors seen in avian feathers presents an intriguing puzzle for materials engineers, as the same building blocks, pigments and keratin, are used to produce radically different plumage. While the showier coloration mechanism of structural color has been investigated from a materials science perspective, the production of pigmentary color, which may be less constrained, has largely been neglected from a structural perspective. I used Scanning Electron Microscopy (SEM) to image the internal feather structure of twelve species of Southern Capuchino Seedeaters (genus Sporophila) over a range of species, colors, and body feather patches. This group of birds is of particular interest due to its low level of genetic differentiation, which shows divergence mainly in the melanogenesis pathway, and therefore represents an opportunity to study the evolution of the mechanisms of plumage coloration. Key findings include: (1) Fontana Masson stain can be used with backscattered electron SEM to image individual granules of melanin within feathers, (2) white feathers are produced by an absence of melanin, (3) either round or oblong melanosomes can contain primarily eumelanin and produce black or grey feathers while only round melanosomes containing a majority of pheomelanin produce cinnamon or rufous colors, (4) oblong melanosomes are associated with the crown patch, and (5) all oblong melanosomes were found in feathers with at least seven times more eumelanin than pheomelanin. This work contributes to our understanding of the link between plumage differences in the Southern Capuchino Seedeaters and specific genetic changes in the deposition of melanosomes and melanin pigments. Furthermore, it presents a new technique for in situ feather melanin visualization, opening the door for analysis of intra-feather melanin patterning and melanin placement within periodic structural color systems.

Journal / Series

Volume & Issue

Description

73 pages

Sponsorship

Date Issued

2023-08

Publisher

Keywords

Feather; Melanin; Melanosome; Sporophila

Location

Effective Date

Expiration Date

Sector

Employer

Union

Union Local

NAICS

Number of Workers

Committee Chair

Estroff, Lara

Committee Co-Chair

Committee Member

Dillman, Casey

Degree Discipline

Materials Science and Engineering

Degree Name

M.S., Materials Science and Engineering

Degree Level

Master of Science

Related Version

Related DOI

Related To

Related Part

Based on Related Item

Has Other Format(s)

Part of Related Item

Related To

Related Publication(s)

Link(s) to Related Publication(s)

References

Link(s) to Reference(s)

Previously Published As

Government Document

ISBN

ISMN

ISSN

Other Identifiers

Rights

Attribution 4.0 International

Types

dissertation or thesis

Accessibility Feature

Accessibility Hazard

Accessibility Summary

Link(s) to Catalog Record