Spot the difference: mimicry in a coral reef fish

Area of Science:

• Animal Behavior
• Evolutionary Biology
• Marine Biology

Background:

• Eyespots on animal bodies are traditionally linked to predator deterrence.
• Recent research questions the sole protective function of eyespots, suggesting alternative roles.
• The functional significance of eyespots may vary across species and life stages.

Purpose of the Study:

• To investigate the function of eyespots on the dorsal fin of juvenile and adult coral reef damselfish (Pomacentrus amboinensis).
• To explore how eyespot presence changes with age, sex, and sexual maturation.
• To determine if eyespots serve purposes beyond predator defense in this species.

Main Methods:

• Examined the occurrence of eyespots in different age and gender groups of Pomacentrus amboinensis.
• Analyzed body shape differences among individuals with and without adult eyespots.
• Observed changes in eyespot presence as fish approached sexual maturation.

Main Results:

• Eyespots are typical in juvenile damselfish and fade with maturation in most adults.
• Adults retaining dorsal fin eyespots were exclusively sexually mature males.
• The body shape of males with adult eyespots resembled immature females more than mature males.

Conclusions:

• Eyespots in Pomacentrus amboinensis exhibit a dual function, changing roles throughout an individual's life.
• Juvenile eyespots may serve as advertisements, while adult eyespots function as a deceptive signal.
• Further experiments like male removal or color manipulation are needed to confirm specific functions.