Color variation in signal crayfish Pacifastacus leniusculus

Area of Science:

• Animal coloration
• Carotenoid-based coloration
• Sexual dimorphism in animals

Background:

• Animal external coloration is influenced by genetics, epigenetics, perception, evolution, and function.
• Camouflage and conspicuousness present opposing selection pressures on animal coloration.
• Crustacean coloration primarily results from carotenoid accumulation, with trade-offs between camouflage and communication driving diverse adaptations.

Purpose of the Study:

• To investigate intrapopulation variability in the external coloration of Pacifastacus leniusculus.
• To explore coloration differences within individuals across body regions and between sexes.

Main Methods:

• Digital image analysis was employed to quantify coloration.
• Variability was assessed across body regions (e.g., ventral vs. upper claw parts).
• Differences between sexes (male vs. female) and across size gradients were examined.

Main Results:

• Ventral claw coloration was more saturated and brilliant than upper parts.
• Males displayed more saturated and brighter coloration than females, particularly on lower claw portions.
• Color intensity and brightness increased with size, with region-specific patterns.
• Color brightness exhibited greater variability in males compared to females.

Conclusions:

• Observed coloration patterns support a compromise between camouflage and conspicuousness for communication in Pacifastacus leniusculus.
• Carotenoids likely play a role in intraspecific communication, serving functions beyond simple pigmentation.