Local parasite pressures and host genotype modulate epigenetic diversity in a mixed-mating fish

Area of Science:

• Evolutionary biology
• Genetics
• Epigenetics

Background:

• Parasite-mediated selection drives genetic variation in natural populations.
• Self-fertilization can reduce genetic diversity, potentially hindering host defense against pathogens.
• DNA methylation is explored as a mechanism for generating adaptive variation in low-diversity populations.

Purpose of the Study:

• To investigate the adaptive role of DNA methylation in a predominantly self-fertilizing fish, Kryptolebias hermaphroditus.
• To analyze the relationship between genetic diversity, DNA methylation variation, and parasite loads.
• To understand how inbreeding and parasite pressure interact to shape epigenetic variation.

Main Methods:

• Microsatellite and AFLP markers were used to assess genetic diversity.
• Methylation-sensitive AFLPs (MS-AFLPs) were employed to quantify DNA methylation variation.
• Parasite loads were measured in three distinct populations of K. hermaphroditus.

Main Results:

• Strong genetic population structuring was observed in K. hermaphroditus.
• Significant differences in parasite loads and DNA methylation levels were found among populations and selfing lineages.
• Parasite presence was a key factor influencing DNA methylation levels at local scales, interacting with inbreeding effects.

Conclusions:

• DNA methylation can provide adaptive variation in predominantly self-fertilizing species.
• Parasite-host interactions play a crucial role in shaping epigenetic variation.
• Epigenetic mechanisms like DNA methylation may be vital for host adaptation in environments with high parasite pressure and low genetic diversity.