Small and neglected: Unraveling the diversity and phylogenetic relationships of helminths parasitic on native fishes from the Paranapanema River basin (SP/PR)

• Grant number: 24/15651-1
• Support Opportunities: Regular Research Grants
• Start date: April 01, 2025
• End date: March 31, 2028
• Field of knowledge: Agronomical Sciences - Fishery Resources and Fishery Engineering - Inland Water Fishery Resources
• Principal Investigator: Reinaldo José da Silva
• Grantee: Reinaldo José da Silva
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated researchers: Gerardo Perez Ponce de Leon ; Julio Cesar Cenci de Aguiar ; Lorena Gisela Ailán Choke ; Mariana Bertholdi Ebert ; Philippe Vieira Alves ; Ricardo Cardoso Benine

Abstract

Fishes are the vertebrates with the largest number of host-parasite associations, encompassing parasites from different phyla and even different kingdoms. It is estimated that only 6% of Brazilian fish species have been studied regarding their parasitic fauna and, therefore, knowledge about the biodiversity of fish parasites is still incipient in Brazil. Among fish parasites, helminths stand out due to the great diversity (approximately 1,200 species) already described in these animals. Despite this, the evolutionary history of several taxa at different hierarchical taxonomic levels in the Neotropical region is uncertain, given the absence of molecular phylogenies for most groups. Even when present, the low phylogenetic signal in certain analyses makes it difficult to understand the evolutionary history of the parasites involved. Such gaps make it difficult to establish robust and unequivocal hypotheses regarding the validity of independent lineages/species, monophyletic groups and, consequently, of all knowledge about the biodiversity of these organisms. Furthermore, helminths are the most impactful parasites from a health point of view, especially considering the frequency of occurrence of these parasites in native fish. Thus, the present work aims to study, based on morphological and molecular data, the diversity, taxonomy and systematics of helminth parasites of 57 species of native fish from rivers of the Paranapanema River basin, in the states of São Paulo and Paraná. For this study, morphological analyses will be performed in conjunction with molecular analyses using ribosomal (SSU rDNA, LSU rDNA and ITS) and mitochondrial (COI) markers. High-throughput sequencing strategies will be employed to answer complex taxonomic questions in the different groups of helminths studied. For this purpose, complete mitogenomes and the nuclear rRNA operon of up to 50 individuals will be generated through Next Generation Sequencing (NGS) and the genome skimming strategy. The results obtained during the project will be important for knowledge of Brazilian biodiversity, a better understanding of the structure of parasite communities, taxonomy, systematics and phylogeny of parasites in fish species in an environment still little explored in the Paranapanema River basin. (AU)