EVOLUTION OF INCOMPATIBILITY-INDUCING MICROBES AND THEIR HOSTS

Area of Science:

• Evolutionary biology
• Microbial genetics
• Insect reproductive systems

Background:

• Wolbachia pipientis bacteria induce reproductive incompatibility in many insect species.
• Infected males and uninfected females produce fewer offspring, aiding infection spread via maternal transmission.

Purpose of the Study:

• Analyze evolutionary selection on parasite and host genes within Wolbachia-induced incompatibility systems.
• Understand the dynamics of gene spread and maintenance in host-parasite interactions.

Main Methods:

• Theoretical analysis of selection pressures on host and parasite genes.
• Modeling of gene dynamics in populations with maternally inherited symbionts.

Main Results:

• Parasite selection favors increased progeny production by infected mothers, not necessarily higher incompatibility.
• Rare, productivity-reducing parasites can spread locally, analogous to underdominant chromosome rearrangements.
• Within-population selection generally increases infected female fecundity and transmission efficiency.

Conclusions:

• Host and parasite gene evolution tend to harmonize due to vertical transmission.
• Competition among parasite variants can maintain incompatibility despite selection pressures.
• Host gene selection favors increased compatibility between infected males and uninfected females.