Evolution of phenotypic fluctuation under host-parasite interactions.

Area of Science:

• Evolutionary Biology
• Systems Biology
• Genetics

Background:

• Biological systems require robustness and plasticity to adapt to environmental variability.
• Phenotypic variance is linked to robustness and plasticity, typically decreasing with increased robustness.
• Inter-species interactions, like host-parasite dynamics, are key environmental factors influencing phenotypic evolution.

Purpose of the Study:

• To investigate how host-parasite interactions drive the evolution of phenotypic variance and the genotype-phenotype map.
• To explore the mechanisms by which phenotypic fluctuation is maintained or increased in response to parasitic pressure.

Main Methods:

• A dynamic gene expression model for host-parasite systems was employed.
• The study analyzed the evolution of the genotype-phenotype map and phenotypic variances.
• Simulations examined the impact of interaction strength and gene expression noise thresholds.

Main Results:

• Weak host-parasite interactions favor host phenotypes with reduced variance for robustness.
• Strong interactions promote increased host phenotypic variance to evade parasite detection.
• Two strategies for increasing variance were identified: genetic diversification and noise-induced fluctuation, dependent on noise levels.

Conclusions:

• Host-parasite interactions can override the general trend of decreasing phenotypic variance.
• Gene expression noise and genetic mutations play crucial roles in the evolution of phenotypic fluctuation and robustness.
• A trade-off exists between increased phenotypic variance and host growth rate.