Chemical defences indicate bold colour patterns with reduced variability in aposematic nudibranchs

Area of Science:

• Evolutionary Biology
• Chemical Ecology
• Marine Biology

Background:

• Phenotypic diversity in prey communities with aposematic animals is influenced by secondary defenses.
• Quantitative data on color pattern variation and chemical defenses in aposematic species assemblages are limited.

Purpose of the Study:

• To quantitatively assess color pattern diversity and chemical defense strength in 13 dorid nudibranch species.
• To investigate the relationship between chemical defenses and visual characteristics of aposematic prey.

Main Methods:

• Quantitative Color Pattern Analysis (QCPA) was used to quantify color pattern diversity.
• The visual system of a triggerfish (Rhinecanthus aculeatus) and viewing distances (2 and 10 cm) were modeled.
• Chemical defense strength was assessed across species.

Main Results:

• Increased chemical defenses correlated with increased color pattern boldness (higher visual contrast).
• Species with chemical defenses exhibited less color pattern variability compared to undefended species.
• Distinct color pattern properties were associated with the presence and strength of chemical defenses.

Conclusions:

• Aposematic coloration is linked to secondary defense strength, with bolder and less variable patterns associated with stronger chemical defenses.
• Predator perception of spatiochromatic properties can indicate the presence and intensity of chemical defenses in prey.