Genetic Diversity and Population Dynamics of Clinostomum spp. Using Comprehensive Bioinformatics Approaches

Clinostomum species, a parasitic pathogen of freshwater fish, is widely distributed and infects various host species. Recently, the pathological effect due to Clinostomum metacercarial infection was described in aquaculture in Thailand; however, the global genetic diversity and population structure of this species have not been studied yet. Therefore, this study aimed to provide a detailed description of genetic diversity and population dynamics of the digenean Clinostomum isolated from Trichopodus pectoralis with globally recorded Clinostomum species. The species was characterized molecularly by analyzing 18S rDNA and inter-transcribed spacer biomarker genes (ITS1 and ITS2). A BLAST search discovered that the 18S rDNA and ITS sequence had a 100% sequence similarity with Clinostomum piscidium isolated from India and Thailand. A comprehensive analysis revealed the presence of 12 distinct haplotypes among the Clinostomum populations. This study suggests that distinct patterns of genetic variation were identified by analyzing molecular variance, pairwise Fst, and employing structure analysis. It was observed that a gradient of genetic variation exists within continents, characterized by higher levels within different groups and lower levels of genetic differentiation. Additionally, a notable presence of mixed haplotypes was observed. The results of neutrality testing suggest that there has been a significant expansion in the populations of Clinostomum in India, America, and Kenya. The discoveries from this study will provide a valuable contribution to comprehending the genetics and evolution of Clinostomum species. Furthermore, key findings will be essential in developing efficient management approaches to prevent and control this parasite.