Warning signals are under positive frequency-dependent selection in nature

Area of Science:

• Ecology
• Evolutionary Biology
• Animal Behavior

Background:

• Positive frequency-dependent selection (FDS) is hypothesized to drive adaptive signaling and communication strategies.
• The natural operation of positive FDS, particularly in mimicry systems, remains poorly understood, limiting insights into signal diversity.

Purpose of the Study:

• To investigate the presence and mechanism of positive FDS in the warning color patterns of Amazonian butterflies.
• To determine how the frequency of warning signals influences their protective efficacy against predators.

Main Methods:

• Utilized artificial prey models with varying frequencies of warning coloration in natural Amazonian communities.
• Assessed the relationship between the local frequency of warning signals and their protective effectiveness by observing predator interactions.

Main Results:

• Demonstrated that warning signal efficiency increases with its local frequency, stabilizing at higher frequencies.
• Found that predator avoidance knowledge, integrated across the community, dictates signal protection, with common signals offering saturated protection.
• Observed that most warning signals are incompletely known by predators, providing incomplete protection.

Conclusions:

• Positive FDS operates in butterfly mimicry, driven by predator learning and avoidance.
• Incomplete predator knowledge of warning signals favors the evolution of life history traits that increase signal frequency and visibility.
• Strategies like gregariousness or niche convergence may evolve to enhance warning signal efficiency through improved predator learning.