The origin of polymorphic crypsis in a heterogeneous environment.

Area of Science:

• Evolutionary Biology
• Ecology
• Theoretical Biology

Background:

• Polymorphic crypsis, the evolution of camouflage in multiple forms within a species, is a known phenomenon but lacks a robust theoretical framework.
• Understanding how a single prey species can evolve effective camouflage in distinct, non-isolated habitats presents a significant theoretical challenge.

Purpose of the Study:

• To develop and analyze a theoretical model explaining the evolutionary mechanisms behind polymorphic crypsis in prey species inhabiting two connected environments.
• To investigate the roles of key ecological and evolutionary parameters, such as dispersal rate, habitat-specific crypsis trade-offs, and predation levels, in driving evolutionary branching.

Main Methods:

• A mathematical model was developed to simulate a prey species with passive dispersal between two distinct habitats.
• The model analyzed the conditions under which evolutionary branching occurs, leading to the maintenance of multiple cryptic morphs.
• Predator functional responses (Type II and Type III) were incorporated to assess their impact on the evolutionary dynamics.

Main Results:

• Evolutionary branching, resulting in polymorphic crypsis, is promoted by intermediate values of dispersal rate, crypsis trade-offs, and predation intensity.
• A larger parameter space favors evolutionary branching under a Type III functional response compared to a Type II response.
• The model predicts outcomes ranging from single-habitat specialists to intermediate generalists, alongside the emergence of polymorphic species.

Conclusions:

• The study provides a theoretical foundation for polymorphic crypsis, demonstrating that evolutionary branching can lead to prey species adapting to multiple habitats.
• The interplay between dispersal, predation, and habitat-specific adaptations is crucial for the evolution of multiple cryptic forms.
• Predator functional response significantly influences the likelihood and extent of evolutionary branching in prey populations.