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.

Effects of Background Color and Predation Risk on Color Change in Fire Salamander Larvae

2009 ◽  
Vol 55 (4) ◽  
pp. 359-367 ◽  
Author(s):  
Ori Segev
Keyword(s):  
Predation Risk ◽  
Perceived Risk ◽  
Color Change ◽  
White Background ◽  
Color Matching ◽  
Background Color ◽  
Background Matching ◽  
Threat Sensitivity ◽  
Risk Of Predation ◽  
Fire Salamander

The threat-sensitivity hypothesis assumes individuals should demonstrate flexibility in response to perceived predation risk and vary the intensity of anti-predator responses in concert with perceived risk of predation. Substrate color matching is adaptive as it enables organisms to become less conspicuous to both their prey and predators. I hypothesized that newborn fire salamander (Salamandra infraimmaculata) larvae will respond fast through physiological color change to contrasting backgrounds, becoming lighter against a white background and darker against a black background. Additionally, in accordance with the threat-sensitivity hypothesis, I expected a background color x predator interaction—i.e., that predator presence will further enhance the focal larvae color-matching response. To explicitly test these hypotheses I conducted a replicated outdoor mesocosm experiment. I used a two-by-two factorial design: pools of black or white background color crossed with the presence or absence of a larger cannibalistic conspecific. Digital photos of the focal larvae's dorsal view revealed that larval brightness and chroma changed accordingly against the contrasting black and white backgrounds to increase background matching. Although not statistically significant, larvae tended to show a stronger color-change response towards enhanced background matching in the presence of the free predator. Larval survival was strongly reduced in the presence of the larger conspecific, with no apparent effect of background color. This study demonstrates that Salamandra larvae are capable of environmentally induced physiological color change and highlights the need for further investigation into the interplay between threat intensity, mechanisms of risk assessment, and physiological antipredator responses.

Hind Limb Anomalies of a Western Montana Population of the Pacific Tree Frog, Hyla regilla Baird and Girard

Copeia ◽  
1963 ◽  
Vol 1963 (3) ◽  
pp. 570 ◽  
Author(s):  
William B. Hebard ◽  
Royal Bruce Brunson
Keyword(s):  
Hind Limb ◽  
Western Montana ◽  
Tree Frog ◽  
Hyla Regilla ◽  
Limb Anomalies ◽  
The Pacific

INFLUENCE OF WATER TEMPERATURE ON ACETYLCHOLINESTERASE ACTIVITY IN THE PACIFIC TREE FROG (HYLA REGILLA)

2005 ◽  
Vol 24 (8) ◽  
pp. 2074 ◽  
Author(s):  
Catherine S. Johnson ◽  
Steven E. Schwarzbach ◽  
John D. Henderson ◽  
Barry W. Wilson ◽  
Ronald S. Tjeerdema
Keyword(s):  
Water Temperature ◽  
Acetylcholinesterase Activity ◽  
Tree Frog ◽  
Hyla Regilla ◽  
The Pacific ◽  
Influence Of Water

The effect of metamorphosis on the repeatability of maximal locomotor performance in the Pacific tree frog Hyla regilla.

1997 ◽  
Vol 200 (20) ◽  
pp. 2663-2668
Author(s):  
T B Watkins
Keyword(s):  
Evolutionary Biology ◽  
High Performance ◽  
Developmental Stages ◽  
Tree Frog ◽  
Locomotor Performance ◽  
Hyla Regilla ◽  
Performance Variation ◽  
The Pacific ◽  
Burst Swimming ◽  
Individual Consistency

Measuring the repeatability of inter-individual differences in locomotor performance is an important first step in elucidating both the functional causes and the ecological consequences of performance variation. Thus, repeatability of whole-animal performance traits provides a crucial link between functional and evolutionary biology. In the present study, repeatability of maximal burst locomotor performance was estimated for a single population of the Pacific tree frog Hyla regilla. Animals were reared individually from eggs through metamorphosis in the laboratory. Maximum burst swimming speed of tadpoles was measured before metamorphosis (Gosner stage 37) and again at the onset of the metamorphic climax (stage 42). Maximum jump distance was measured on the same individuals as juvenile frogs. Locomotor performance was repeatable over a 24h period for both premetamorphic tadpoles and juvenile frogs. Performance was not repeatable across metamorphosis or between any two of the three developmental stages investigated. A high-performance individual at one developmental stage does not necessarily retain that performance advantage at another stage. This lack of repeatability contrasts sharply with several previous studies on non-metamorphosing vertebrates, but concurs with a single previous study on a metamorphosing salamander. Metamorphosis appears to place strict temporal constraints on individual consistency in locomotor ability.

'Handedness' in the Pacific tree frog (Hyla regilla)

1977 ◽  
Vol 55 (11) ◽  
pp. 1926-1929 ◽  
Author(s):  
Lawrence M. Dill
Keyword(s):  
Tree Frog ◽  
Hyla Regilla ◽  
The Pacific ◽  
The Mean ◽  
Tree Frogs ◽  
The Right ◽  
Model Predator

The jumping directions of 24 individual Pacific tree frogs (Hyla regilla), in response to repeated presentations of a model predator, were recorded. The mean jump angle was 70° from the frog's initial bearing regardless of whether the jump was to the left or the right. There was a slight bias within the sample towards left jumps, and most frogs had longer right than left hindlimbs. Some individual frogs jumped preferentially to the left, indicating the existence of 'handedness' in this species.

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