Sistemática e Evolução - Pôsteres - 29/11/2023 - 15:30 h às 16:30 h

Amphipods are small crustaceans of the superorder Peracarida, which includes species distributed in marine, freshwater, and terrestrial environments worldwide. Several species within this order are considered epibionts, and due its direct development, they are expected to have a low dispersal capacity, and likely be endemic. However, gene flow capability and genetic structuring of marine epibionts can also be influenced by the host. Here, we aimed to uncover the genetic diversity patterns of Podocerus chelonophilus (Chevreux & Guerne, 1888), an epibiont of the loggerhead turtle (Caretta caretta (Linnaeus, 1758)). We used sequence data based on the mitochondrial cytochrome b gene (Cyt b) and the nuclear internal transcribed spacer region (ITS-1) of 119 individuals from 22 turtles belonging to 3 localities: Arembépe (BA), Povoação and Regência (ES), a distance of 1,220 km on coast. Analyses showed high diversity, with 25 (Cyt b) and 24 (ITS-1) haplotypes but with no clear geographic pattern in the haplotype network. Genetic diversity analyses showed higher molecular diversity indices values for the ITS-1 marker (ϴπ: 41.4; ϴs: 13; ϴk: 26). We estimated pairwise genetic structure between turtles (average Cyt b F_ST : 0 to 0.55; ITS-1; F_ST : 0 to 0.52) and localities (average Cyt b F_ST : 0 to 0.002; ITS-1; F_ST: 0 to 0.01), showing no genetic differentiation among them. The AMOVA analysis also presented evidence of high connectivity between localities and turtles (Cyt b F_ST: 0.005; ITS-1; F_ST : 0.00) with most of the genetic variation contained within turtles. The lack of genetic structuring among localities, may indicate that crossbreeding of epibionts only occurs in turtle’s feeding and nesting areas. This is the first phylogeographical study of a sea turtle epibiont on the Brazilian coast. These results can greatly contribute to the knowledge regarding the dispersal of epibiont crustacean species, and indirectly give us a glimpse of the populational dynamics of its hosts.