The Shapes of Birds' Eggs

Mallock, A.

doi:10.1038/116311a0

Cited by 11 publications

(10 citation statements)

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“…When such a membrane is pressurized, it distends and takes up a form deter-mined by two types of variation across the egg's surface: (i) variation in applied pressure difference across the surface; and (ii) variation in the membrane's thickness and material properties across the surface. We extend previous work that has alluded to these ideas qualitatively (20)(21)(22) by constructing a mathematical model that connects to the available experimental literature and emphasizes the central role played by the membrane. This model accounts for (i) differential forcing on the membrane from external muscular forces and internal pressure and (ii) variations in membrane properties in the axial and azimuthal directions.…”

Section: A Biophysical Model Of Egg Shapementioning

confidence: 62%

Avian egg shape: Form, function, and evolution

Stoddard

Yong

Akkaynak

et al. 2017

Science

188

315

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21Avian egg shape is generally explained as an adaptation to life history, yet we currently lack a global 22 synthesis of how egg shape differences arise and evolve. Here, we apply morphometric, mechanistic and 23 macroevolutionary analyses to the egg shapes of ~1400 bird species. We characterize egg shape diversity in 24 terms of two biologically relevant variables, asymmetry and ellipticity, allowing us to quantify the observed 25 morphologies in a two-dimensional morphospace. We then propose a simple mechanical model that explains 26 the observed egg shape diversity based on geometric and material properties of the egg membrane. Finally, 27 using phylogenetic models, we show that egg shape correlates with flight ability on broad taxonomic scales, 28suggesting that adaptations for flight may have been critical drivers of egg shape variation in birds. 29 30

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Section: A Biophysical Model Of Egg Shapementioning

confidence: 62%

Avian egg shape: Form, function, and evolution

Stoddard

Yong

Akkaynak

et al. 2017

Science

188

315

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“…Computational Fourier analysis has been used for the study of the perimeters and internal structures of organs and organisms (1 1, 94, 101,112,119,159,187). But most applications of these optical Fourier transforms are in sciences other than biology.…”

Section: Morphometric Methodsmentioning

confidence: 99%

One Biologist's View of Morphometrics

Oxnard¹

1978

Annu. Rev. Ecol. Syst.

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“…The mathematical description of egg shape has a long history of research that continues to this day (Mallock , Preston , , , Smart , , Todd and Smart , Baker , Deeming and Ruta , Troscianko , Mytiai et al , Stoddard et al ). Other than the challenge of describing a complex shape, the study of egg shape has been useful in calculating volume or surface area of eggs (Hoyt ) and in assessing eggshell strength (Bain , Anderson et al , Nedomova et al ).…”

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confidence: 99%

Effect of composition on shape of bird eggs

Deeming

2017

Journal of Avian Biology

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Abstract:Numerous studies over the past 90 years have described the various bird egg shapes in mathematical terms but few studies have considered the underlying reasons for such interspecific egg shape variability. This study investigated how the size and composition, i.e. proportions of shell, yolk and albumen, were associated with egg shape. Geometric morphometrics were used to generate principal components, which were analysed in relation to taxonomy (i.e. avian order) and degree of neonatal developmental maturity, which correlates with egg composition. The analysis confirmed previous results that most of the variation in shape is associated with degree of elongation (i.e. length divided by breadth) and asymmetry (i.e. position of the broadest part of the egg away from the mid-point of the egg's length). Egg shape reflected both avian order but not developmental maturity. The degree of elongation of an egg is related to absolute egg mass and the proportion of yolk. By contrast, the degree of asymmetry is related to the proportion of shell and the mass of the egg relative to female body mass. Although significant, the models explained little of the variation in egg shape and so it was concluded that other factors, such as pelvis size and shape, could be more important in determining egg shape in birds. Numerous studies over the past 90 years have described the various bird egg shapes in mathematical 8 terms but few studies have considered the underlying reasons for such interspecific egg shape 9 variability. This study investigated how the size and composition, i.e. proportions of shell, yolk and 10 albumen, were associated with egg shape. Geometric morphometrics were used to generate principal 11 components, which were analysed in relation to taxonomy (i.e. avian order) and degree of neonatal 12 developmental maturity, which correlates with egg composition. The analysis confirmed previous 13 results that most of the variation in shape is associated with degree of elongation (i.e. length divided 14 by breadth) and asymmetry (i.e. position of the broadest part of the egg away from the mid-point of 15 the egg's length). Egg shape reflected avian order but not developmental maturity. The degree of 16 elongation of an egg is related to absolute egg mass and the proportion of yolk. By contrast, the 17 degree of asymmetry is related to the proportion of shell and the mass of the egg relative to female 18 body mass. Although significant, the models explained little of the variation in egg shape and so it 19 was concluded that other factors, such as pelvis size and shape, could be more important in 20 determining egg shape in birds. 21 22 Journal of Avian Biology

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The Shapes of Birds' Eggs

Cited by 11 publications

References 0 publications

Avian egg shape: Form, function, and evolution

Avian egg shape: Form, function, and evolution

One Biologist's View of Morphometrics

Effect of composition on shape of bird eggs

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