Adaptive variation in avian eggshell gas conductance and structure across elevational gradients?
- Department of Ecology and Evolutionary Biology, Princeton University, United States
- Laboratorio de Biología Evolutiva de Vertebrados, Departamento de Ciencias Biológicas, Universidad de Los Andes, Colombia
- Departamento de Ingeniería de Sistemas y Computación, Universidad de los Andes, Colombia
- Division of Asthma Research, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, University of Cincinnati College of Medicine, United States
- Departamento de Ciencias Biológicas, Bioprocesos y Biotecnología, Universidad Icesi, Colombia
Figures
Figure 1 with 1 supplement
Variation in eggshell conductance across Andean bird species.
(a) Phylogeny of the studied species visualized using iTOL v. 6.7.4. (Letunic and Bork, 2021). The internal half-circle represents orders in colors, the external half-circle represents elevations, and the grey bars represent the residual values of conductance. (b) The significant positive relationship (log Conductance = β₀ + β₁·log Mass; R² = 0.63, p < 0.001) between log-transformed egg mass and log-transformed eggshell conductance across 108 species of birds in three elevational zones (Lowland, Mid-Elevation, Highland). Shaded areas represent 95% confidence intervals around the regression lines. Colors and shapes indicate elevation categories; egg photos by DO for Threnetes leucurus, Atlapetes melanolaemus, and Tinamus major. (c) Residual conductance of species occupying three different elevational ranges (Phylogenetic ANOVA; F2, 106 = 4.46, P < 0.001; lowland n = 44; medium elevation n = 43; and highland n = 18); significant differences indicated with *. Note that lowland species show wide conductance values with a mean above the expected, given the allometric relationship. Highland species exhibit less variation, and the conductance is lower than expected for the size of their eggs. Bird silhouettes in (a) are from www.phylopic.org (Crypturellus variegatus by JN Wiegers; Haplophaedia aureliae by Edwin Price; Manacus manacus by Edwin Price).
© 2013, Viatour and Plank. The Columba livia domestica image in Figure 1 is reproduced from PhyloPic (published under a CC BY SA license). Further reproductions must adhere to the terms of this license.
Figure 1—figure supplement 1
Analysis excluding large eggs (i.e. >12 g), only present at mid-elevations and in the lowlands.
The model showed a significant positive relationship (log conductance = β0 + β1·log mass; R2=0.16, p<0.0007) between log-transformed egg mass and log-transformed eggshell conductance across 101 species of birds in three elevational zones (lowland, mid-elevation, highland). Shaded areas represent 95% confidence intervals around the regression lines. Colors and shapes indicate elevation categories. Residual conductance of species occupying three different elevational ranges, significant differences (p<0.0004) indicated with *. Note that lowland species show wide conductance values with a mean above the expected, given the allometric relationship. Highland species exhibit less variation, and the conductance is lower than expected for the size of their eggs.
Figure 2
Scanning electron microscopy (SEM) images of the cross-section (a, c, e) and the eggshell surface and eggs species photo/illustration (b, d, f) of Dusky-throated Antshrike (Thamnomanes ardesiacus, a and b), Gray-breasted Wood-Wren (Henicorhina leucophrys, c and d), and Masked Flowerpiercer (Diglossa cyanea, e and f).
White double arrows in a, c, and e show the thickness measurement taken from the eggshell; white circles in b, d, and f point to exposed pores counted, and white arrows in occluded holes. Images by DO, photos by GAL, and bird illustrations by Fernando Ayerbe-Quiñones.
Figure 3
Left: Allometric relationship between (a) thickness, (d) pore density, and (g) pore size and egg volume.
Note that thickness is positively correlated with egg size (p<0.001, n=129), while pore density and egg size are negatively related (p<0.001, n=116); there is no relationship between pore size and egg volume; therefore, we used absolute values. Center: Relationships between residual (i.e. size-independent) thickness (b), pore density (e), absolute pore size (h), and elevation for families distributed along the gradient. In all cases, there are no overall relationships, but both positive and negative relationships are found when data are analyzed separately for species in different families: statistically significant relationships are shown as solid lines, otherwise as dotted lines. Right: Trait evolution of residual thickness (c), pore density (f), and absolute pore size (i). Bird illustrations by Fernando Ayerbe-Quiñones.
Additional files
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MDAR checklist
- https://cdn.elifesciences.org/articles/85564/elife-85564-mdarchecklist1-v2.docx
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Supplementary file 1
Eggshell conductance data across Andean bird species.
- https://cdn.elifesciences.org/articles/85564/elife-85564-supp1-v2.csv
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Supplementary file 2
Eggshell structure data across Andean bird species.
- https://cdn.elifesciences.org/articles/85564/elife-85564-supp2-v2.csv
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Supplementary file 3
Eggshell structure data for two species distributed along the Andean elevational gradient.
- https://cdn.elifesciences.org/articles/85564/elife-85564-supp3-v2.csv
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Supplementary file 4
Models of evolution for the eggshell traits across Andean bird species.
- https://cdn.elifesciences.org/articles/85564/elife-85564-supp4-v2.docx
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Adaptive variation in avian eggshell gas conductance and structure across elevational gradients?
eLife 15:e85564.
https://doi.org/10.7554/eLife.85564
