Sexual dichromatism in the marbled salamander, Ambystoma opacum
Brian
D. Todd1 and Andrew K. Davis2
1Savannah River Ecology Laboratory, The University of Georgia,
Aiken, SC 29802, USA
2Warnell School of Forestry and Natural Resources, University
of Georgia, Athens, GA 30602, USA
Abstract
Reports of sexual dichromatism in salamanders are rare and have been generally
restricted to a few species in the families Hynobiidae and Salamandridae.
We used image analysis techniques to examine sexual dichromatism in the
marbled salamander, Ambystoma opacum (Gravenhorst, 1807). We measured
the average hue of white saddles on male and female marbled salamanders
(n = 118), as well as the proportion of white dorsal surface area
relative to the black dorsal surface area, to determine the extent of
sexual dichromatism in this species. We also tested whether patterning
and coloration were correlated with body size or relative body mass. Males
had significantly whiter saddles and higher relative proportions of white
coloration on their dorsal surfaces than did females. Furthermore, the
relative proportion of white areas on the dorsum was positively correlated
to body condition in both males and females. Body size was not correlated
with hue or proportion of white area on the dorsum. To our knowledge,
we report the first confirmation of sexually dimorphic coloration in the
ambystomatid salamander family, extending the known distribution of sexual
dichromatism in the order Caudata.
SREL Reprint #3052
Todd, B. D. and A. K. Davis 2007. Sexual dichromatism in the marbled salamander,
Ambystoma opacum. Canadian Journal for Zoology 85(9):1008-1013.
