ARE WARNING COLORS HANDICAPS?

Area of Science:

• Evolutionary Biology
• Animal Communication
• Behavioral Ecology

Background:

• The handicap theory posits that costly signals ensure honesty in biological advertising.
• This theory is increasingly applied to signal evolution but often lacks empirical testing.
• Its ability to explain specific signal design features remains largely unexamined.

Purpose of the Study:

• To test the handicap theory's explanation for signal design in warning coloration and mimicry.
• To compare the handicap theory with conventional and null models using realistic assumptions.
• To evaluate predictions regarding conspicuousness, pattern similarity, and Batesian mimicry.

Main Methods:

• Developed a modified handicap model incorporating predator learning.
• Compared predictions of the handicap, conventional, and null models.
• Tested model predictions against existing data on warning coloration and mimicry.

Main Results:

• The full handicap model was unrealistic without modifications.
• Conventional signaling theory better explains conspicuousness, attributing it to signal efficacy.
• Pattern similarity is plausibly explained by predator generalization, not handicap-induced conspicuousness.
• Batesian mimicry is predicted by conventional signaling, but not the handicap theory.

Conclusions:

• The handicap theory inadequately explains key design features of warning coloration and mimicry.
• Conventional signaling theory offers a more robust explanation for these phenomena.
• Further testing is needed for some predictions, but current evidence favors conventional signaling.