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THE STRUCTURES PRODUCING “NON‐IRIDESCENT” BLUE COLOUR IN BIRD FEATHERS
Author(s) -
AUBER L.
Publication year - 1957
Publication title -
proceedings of the zoological society of london
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0370-2774
DOI - 10.1111/j.1096-3642.1957.tb00307.x
Subject(s) - iridescence , feather , structural coloration , geography , zoology , ecology , biology , optics , physics , photonic crystal
Summary.1 The paper deals with the morphology and evolution of feathers of structural colours based on Tyndall's principle (short wavelengths of light are scattered from a cloudy medium, underlaid by pigmentations that absorb long wavelengths). 2 The texture of the cloudy medium, usually of medullary origin, represents a dimensional extreme of vacuolization in feathers without Tyndall colour. 3 Concealed bases of Tyndall‐coloured feathers show primitive conditions, as found in dull‐coloured feathers. Transitions between bases and bright terminal regions are interpreted as evolutionary steps, ontogenetically repeated in retrogression. 4 There are few alternative configurations in pigmentation (1) of medullary or cortical portions, each of them evolved convergently in heterogeneous families: convergence is evident from differences in baso‐terminal transitions (3). 5 Divergence of related species (or of plumage regions in the same species) in late evolutionary phases is suggested by agreement in transitional, but differences in terminal, configurations. 6 Evolution of alternative configurations may be controlled by available quantities of cells: these are sometimes correlated with the body volume. 7 The taxonomic significance of Tyndall configurations has been discussed. 8 Convergent evolution (4) of configurations in Alcedinidae and Thraupidae has been studied in detail. 9 Double medullae in Alcedinidae and Thraupidae may represent stabilization of fluctuant conditions in other families.