Genomic diversity of Ozobranchus (Ozobranchidae: Hirudinida): gene flow patterns and kinship relationships of the species Ozobranchus margoi, a parasite of sea turtles on the Brazilian coast

• Grant number: 24/21688-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2025
• End date: December 31, 2025
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: Sónia Cristina da Silva Andrade
• Grantee: Isabelle Cristine Santos da Silva
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 21/06738-8 - Seascape genetics and comparative genomics: an integrative evolutionary approach in marine invertebrates, AP.BTA.JP2

Abstract

Ozobranchidae Pinto, 1921, one of the first leech families to diverge within Hirudinea, includes two marine genera (Ozobranchus and Bogabdella) and one exclusively freshwater genus (Unoculubranchiobdella), a total of eleven species parasitic on chelonians. Ozobranchus species are found in sea turtles (Chelonia mydas and Caretta caretta) on the Brazilian coast and are often associated with fibroepithelial tumors, which threaten the turtles' long-term survival. In a preliminary analysis, a phylogeny using a mitochondrial marker revealed representatives of the species Ozobranchus margoi and Ozobranchus branchiatus on the Brazilian coast, without host specificity and with low intraspecific genetic variation. At this stage of the study, high-throughput sequencing (HTS) techniques will be used to analyze genetic variation, family and population structure, using genotyping by sequencing (GBS), with SNPs (single nucleotide polymorphisms) as markers. Kinship coefficient will be estimated to determine kinship relationships between leeches parasitizing the same turtle and different hosts. In this context, it is hoped to understand the evolutionary history and gene flow patterns of these parasitic sea turtle leeches, distinguishing subpopulations as well as kinship relationships. This is the first study using SNPs for sea leeches, considering their ecological relevance in parasitizing sea turtles and aiming at the conservation of these threatened vertebrates.