The hypothalamic neurosecretory system of the tree frog Hyla regilla

1957 ◽  
Vol 107 (2) ◽  
pp. 253-271 ◽  
Author(s):  
Lowell D. Wilson ◽  
J. Arthur Weinberg ◽  
Howard A. Bern
Keyword(s):  
Neurosecretory System ◽  
Tree Frog ◽  
Hyla Regilla ◽  
Hypothalamic Neurosecretory System

The control of color change in the Pacific tree frog, Hyla regilla

2004 ◽  
Vol 82 (6) ◽  
pp. 889-896 ◽  
Author(s):  
James C Stegen ◽  
C M Gienger ◽  
Lixing Sun
Keyword(s):  
Light Intensity ◽  
Environmental Variables ◽  
Color Change ◽  
Interactive Effects ◽  
Tree Frog ◽  
Background Color ◽  
Hyla Regilla ◽  
Background Matching ◽  
The Pacific ◽  
Initial Color

A number of environmental variables have been identified as affecting anuran color, but rarely have the interactions between these variables been investigated. In attempt to elucidate the function of color change, we conducted a within-subject, full factorial experiment designed to determine the simple and interactive effects of background, temperature, and light intensity on the rate of color change in the Pacific tree frog (Hyla regilla Baird and Girard, 1852). Color was investigated holistically, as well as by decomposing it into its constituent parts (hue, chroma, and lightness), using digital photography. The rate of color change was faster on the green versus the brown background, at 10 versus 25 °C, and at low versus high light intensity. There was also a significant effect of the interaction between background color and temperature on the rate of color change. We found increased rates of hue, chroma, lightness, and color change with increasing initial hue, chroma, lightness, and color distances between the Pacific tree frog and its background, respectively. In addition, initial color distance covaried with changes in environmental variables. After controlling for initial color distance, and thus the effects of background matching, background color and temperature still showed a significant interaction for their effects on rate of color change. These results suggest that crypsis (i.e., background matching) is not the only function of physiological color change in H. regilla. Physiological color change may also be used to hydro- and (or) thermo-regulate.

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