Invasive chameleons released from predation display more conspicuous colors.

Area of Science:

• Evolutionary Biology
• Animal Behavior
• Ecology

Background:

• Conspicuous social and sexual signals are expected to change when predation pressure lessens.
• Examples in wild species with dynamic color change are rare.
• Jackson's chameleons (Chamaeleo jacksonii) were introduced to Hawaii from Kenya.

Purpose of the Study:

• To investigate character release in dynamic color signals of Jackson's chameleons in Hawaii, where native predators are absent.
• To compare social and anti-predator color displays between native and introduced populations.

Main Methods:

• Comparative analysis of color signals in Jackson's chameleons from Kenya and Hawaii.
• Observation of color changes during male-male contests, courtship, and in response to simulated predators (birds, snakes).

Main Results:

• Hawaiian chameleons exhibited more conspicuous social colors during contests and courtship compared to Kenyan chameleons.
• Introduced chameleons were less cryptic when exposed to predators and showed greater color plasticity.
• Hawaiian chameleon display colors were more conspicuous in their local environment than in their ancestral habitat.

Conclusions:

• Relaxed predation pressure in Hawaii led to significant character release of dynamic social color signals in Jackson's chameleons.
• This study provides a rare example of character release in a species with dynamic color change, influenced by sexual selection and altered predator-prey dynamics.