Host-associated genetic differentiation in the face of ongoing gene flow: ecological speciation in a pathogenic parasite of freshwater fish

Our research delves into ecological speciation through an examination of the tapeworm parasite Ligula intestinalis. This parasite infests a diverse range of fish species, breaches their immune defenses, and exerts a substantial pathogenic effect. Our focus was on understanding the population genetic structure, gene flow, and genomic divergence among parasites from various cyprinid fish hosts that coexist sympatrically. By employing genome-wide Single Nucleotide Polymorphisms (SNPs) and analyzing transcriptome data, we aimed to determine if distinct host species exert selective pressures on these parasite populations.