Dorsal body pigmentation and sexual dimorphism in the marbled salamander (Ambystoma opacum)

Supplementary Material

L.R. Pokhrel 1,2,4 , I. Karsai 1, M.K. Hamed 3 and T.F. Laughlin 1

1 Department of Biological Sciences, East Tennessee State University, Johnson City, Tennessee 37614-1710, USA

2 Department of Environmental Health, East Tennessee State University, Johnson City, Tennessee 37614-1700, USA

3 Virginia Highlands Community College, Abingdon, Virginia 24210-0828, USA

4 Corresponding authors: Lok R. Pokhrel, Department of Environmental Health, East Tennessee State University, Johnson City, Tennessee 37614-1710, USA (Phone: 423-439-5258; Fax: 423-439-5230; E-mail: ).

Total Pages = 5 (including cover page)

Total Figures = 2

Total Tables = 2

Fig. S1. — Residual plot of the best-fit statistical model: standardized residuals of Ln(Dorsal Body White Pigmentation) versus the predicted value of Ln(Dorsal Body White Pigmentation). The horizontal line denotes the mean of the standardized residuals of Ln(Dorsal Body White Pigmentation).

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Fig. S2. — Relationships among dorsal body white pigmentation (natural log, mm2), body mass (g) and sex in adult Ambystoma opacum. Broken (male) and solid (female) lines are the best-fit regression lines.

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Table S1.

Factor loadings for the first 3 Principal Components (PC1, PC2 & PC3) as obtained by Principal Component Analysis for adult Ambystoma opacum. Rotations were converged in 5 iterations. Acronyms are same as in Table 3 of the manuscript.

Variable / Rotated Component Matrix
PC1 / PC2 / PC3
BM / 0.358 / 0.871 / 0.247
SVL / 0.844 / 0.412 / 0.151
DBL / 0.854 / 0.365 / 0.126
DBA / 0.867 / 0.326 / 0.251
EED / 0.898 / 0.271 / 0.132
NW / 0.798 / 0.066 / 0.407
WBFL / 0.900 / 0.238 / 0.144
WBHL / 0.767 / 0.224 / 0.332
DBWP / 0.208 / 0.207 / 0.930
Eigenvalue / 6.621 / 0.802 / 0.521
% Variance explained / 73.562 / 8.912 / 5.789
Cumulative variance (%) / 73.562 / 82.474 / 88.262

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Table S2.

Sex-wise Pearson’s correlation coefficient ‘r’ obtained for dorsal body white pigmentation (DBWP; as dependent variable) and several other body traits (as independent variable). Acronyms are same as in Table 3 of the manuscript.

Independent Variable / DBWP
Correlation ‘r’
Male / Female
BM / 0.553 / 0.306
SVL / 0.768 / 0.296
DBL / 0.726 / 0.267
DBA / 0.787 / 0.386
EED / 0.708 / 0.190
NW / 0.704 / 0.300
WBFL / 0.681 / 0.211
WBHL / 0.643 / 0.297

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