Testing hypotheses on the origin and dispersion of Limnoperna fortunei (Bivalvia, Mytilidae) in the Iguassu River (Paraná, Brazil): molecular markers in larvae and adults

Abstract

The invasive bivalve Limnoperna fortunei (Dunker 1857) was introduced in South America in 1991, with the first occurrence in Brazil in 1998. In the Iguassu River, the species was recorded in 2001; however, it is unknown how it was introduced and spread. Adults and larvae were sampled in Iguassu and Parana Rivers, and the genetic profiles were compared. The species was absent in the upper reaches and only larvae were found, in low densities, in intermediary reaches. The L. fortunei populations from the lower Iguassu River presented no genetic differentiation among themselves, suggesting strong connectivity, and were significantly different from the Parana River populations, most likely because of Iguassu Falls. Furthermore, the results suggest that the Parana River represents the source of propagules to the Iguassu River. Generally, no significant differences were observed between the genetic structure inferred from adults and larvae. Only the population from the Iguassu National Park, a lotic environment, differed from the remaining subpopulations. The characterization of genetic profile using larval stages of L. fortunei populations was satisfactory, and represents an important protocol for studying the population genetics of aquatic species with planktonic larval stages.