The feather of the guinea fowl and a mathematical theory of individual feather patterns

Hardesty, Mary

doi:10.1002/jez.1400660104

Cited by 11 publications

(6 citation statements)

References 10 publications

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“…Plate 1 of Hardesty () provides an example of this phenomenon. Photographs show a series of mature and developing guinea fowl breast feathers.…”

Section: Discussionmentioning

confidence: 99%

“…Photographs show a series of mature and developing guinea fowl breast feathers. The mature feathers are patterned with an array of white round dots whereas the corresponding developing feather germs are patterned with an array of white elongated ovals (Hardesty, ). Presumably, white ovals are patterned during development and are then transformed into circles through barb angle expansion when the breast feathers unfurl from their sheaths.…”

Section: Discussionmentioning

confidence: 99%

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Theory of the development of curved barbs and their effects on feather morphology

Feo

Simon

Prum

2016

Journal of Morphology

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Feathers exhibit an extraordinary diversity of shapes, which are used by birds to accomplish a diverse set of functions. Pennaceous feathers have a double branched morphology that develops from a tube of epidermis, and variation in branch geometry determines feather shape. Feather development is both complex (i.e., a simple developmental modification can have multiple effects on mature feather shape), and redundant (i.e., different developmental modifications can create the same shape). Due to this, it is not readily apparent how different feather shapes develop. In many feathers, barbs are not straight, but instead curve in toward, or away, from the feather tip. Barb curvature can affect the shape of mature feathers but the development of curved barbs is unknown. Previous research has hypothesized that barb curvature could develop either during the helical growth of barb ridges in the tubular feather germ, or during barb angle expansion as the feather unfurls from the sheath. To better understand the development of curved barbs and their effects on mature feathers we present a theoretical model of curved barb development and test the model with empirical investigations of feathers. We find that curved barbs affect many aspects of feather morphology including vane width, barb length, and barb spacing. In real feathers, curved barbs can develop both during helical barb ridge growth and during barb angle expansion, with most of the observed curvature due to barb angle expansion. Our results demonstrate that barb angle expansion as a feather unfurls from the sheath is a complex and dynamic process that plays an important role in determining the shape and structure of mature feathers. Curved barbs create heterogeneity in barb geometry within the feather vane, which could have important implications for aerodynamic function and the development of within feather pigmentation patterns. J. Morphol. 277:995-1013, 2016. © 2016 Wiley Periodicals, Inc.

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“…Plate 1 of Hardesty () provides an example of this phenomenon. Photographs show a series of mature and developing guinea fowl breast feathers.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Theory of the development of curved barbs and their effects on feather morphology

Feo

Simon

Prum

2016

Journal of Morphology

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“…Second, pigmentation patterns in some bird feathers exhibit anomalous, unpredictable deviations in pattern (i.e. fused guineafowl dots; Hardesty (1933)). Because these pattern anomalies are repeated identically in the subsequent feathers grown from the same follicles (Hardesty 1933), they are likely to be caused by variations in conditions that are intrinsic to individual follicles and that are determined early in the development of follicle identity.…”

Section: Discussion (A) Realism Of the Modelsmentioning

confidence: 99%

“…A common anomaly in the simulated guineafowl patterns shows a striking congruence with developmental anomalies observed in real guineafowl feathers. Hardesty (1933) observed that neighbouring dots within an isochronic (i.e. chevron-shaped) row of dots on a guineafowl contour feather occasionally unite into a Proc.…”

Section: (A) Simulations Of Within-feather Patternsmentioning

confidence: 99%

“…Currently, there is no generalized theory for the developmental determination of feather pigmentation patterns. Hardesty (1933) made an outstanding early attempt. Almost 20 years before Alan Turing (1952), Hardesty used the reinforcing interactions among wave equations to model the formation of the patterned arrays of dots of a guineafowl feather.…”

Section: Introductionmentioning

confidence: 99%

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Reaction–diffusion models of within-feather pigmentation patterning

Prum

Williamson

2002

Proc. R. Soc. Lond. B

113

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Feathers are complex, branched keratin structures that exhibit a diversity of pigmentation patterns. Feather pigments are transferred into developing feather keratinocytes from pigment cells that migrate into the tubular feather germ from the dermis. Within-feather pigment patterns are determined by differential pigmentation of keratinocytes within independent barb ridges during feather development. Little is known about the molecular mechanisms that determine which keratinocytes receive pigment. We apply reactiondiffusion models to the growth of within-feather pigment patterns based on a realistic model of feather growth. These models accurately simulate the growth of a diversity of the within-feather pigmentation patterns found in real feathers, including a central patch, a 'hollow' central patch, concentric central patches, bars, chevrons, a central circular spot, rows of paired spots, and arrays of offset dots. The models can also simulate the complex transitions between distinct pigmentation patterns among feathers observed in real avian plumages, including transitions from bars to chevrons, bars to paired dots, and bars to arrays of dots. The congruence between the developmental dynamics of the simulated and observed feather patterns indicates that the reaction-diffusion models provide a realistic and accurate description of the determination of pigment pattern within avian feather follicles. The models support the hypothesis that within-feather pigmentation patterning is determined by antagonistic interactions among molecular expression gradients within the tubular follicle and feather germ.

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The effect of thyroxin injections upon the feather of the guinea fowl

Hardesty

1935

J. Exp. Zool.

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The feather of the guinea fowl and a mathematical theory of individual feather patterns

Cited by 11 publications

References 10 publications

Theory of the development of curved barbs and their effects on feather morphology

Theory of the development of curved barbs and their effects on feather morphology

Reaction–diffusion models of within-feather pigmentation patterning

The effect of thyroxin injections upon the feather of the guinea fowl

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