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05:10
Measuring the Behavioral Effects of Intraocular Scatter
Published on: February 18, 2021
A quantitative test of the predicted relationship between countershading and lighting environment
William L Allen1, Roland Baddeley, Innes C Cuthill
1School of Experimental Psychology, University of Bristol, United Kingdom. will.allen@nyu.edu
The American Naturalist
|November 15, 2012
Summary
Countershading, a common animal coloration, helps conceal self-shadows (SSC) in ruminants. This camouflage is influenced by habitat, latitude, and body size, aiding predator avoidance.
Area of Science:
- Zoology
- Animal Behavior
- Evolutionary Biology
Background:
- Countershading, a dark-dorsal to light-ventral coloration, is prevalent in the animal kingdom.
- Its adaptive function, particularly self-shadow concealment (SSC), remains debated.
Purpose of the Study:
- To test the self-shadow concealment (SSC) hypothesis for countershading in ruminants.
- To identify ecological and phylogenetic correlates of countershading intensity.
Main Methods:
- Calculated optimal countershading for SSC based on illumination models.
- Compared model predictions to calibrated images of 114 ruminant species.
- Utilized phylogenetic analyses to determine predictors of countershading.
Main Results:
- Many ruminant species exhibited countershading close to the SSC model's optimum.
- Stronger countershading correlated with open habitats, equatorial proximity, and smaller body size.
- Abrupt tonal transitions were linked to open environments, not group size or antipredator behavior.
Conclusions:
- The SSC hypothesis provides a robust explanation for observed countershading patterns in ruminants.
- Despite variations, countershading likely functions in predator avoidance by minimizing shadows.
- Non-countershaded and reverse-countershaded species highlight the complexity of camouflage strategies.
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