The evolution of phenotypic polymorphism: randomized strategies versus evolutionary branching

Area of Science:

• Evolutionary biology
• Theoretical ecology
• Genetics

Background:

• Phenotypic polymorphism describes populations with distinct phenotypes, influencing traits like reproduction, feeding, and predator defense.
• Phenotype determination can occur randomly, be genetically controlled, or influenced by environmental cues, leading to mixed, genetic, or conditional strategies.

Purpose of the Study:

• To develop a unifying evolutionary theory for the determination of alternative phenotypes using adaptive dynamics.
• To compare the evolutionary outcomes of random phenotype determination versus genetic determination (genetic polymorphism).

Main Methods:

• Utilized the adaptive dynamics framework, extending the analysis of evolutionary branching.
• Compared the likelihood of evolutionary branching (leading to genetic polymorphism) against the evolution of a mixed strategy.
• Based the comparison on the strength of selection acting on different evolutionary outcomes.

Main Results:

• A criterion was derived to determine when genetic polymorphism is favored over random phenotype determination.
• Genetic polymorphism is favored when an individual's heritable genotype serves as an adaptively advantageous cue for development.
• The study suggests that genetic polymorphism can be viewed as a specific instance of phenotypic plasticity.

Conclusions:

• Adaptive dynamics provides a unified framework for understanding the evolution of alternative phenotypes.
• The heritability of a genotype can be a key factor driving the evolution of genetic polymorphism.
• Recognizing genetic polymorphism as a form of phenotypic plasticity offers new insights into evolutionary strategies.