Diversidade genética, filogeografia e taxonomia de cladóceros (Crustacea, Branchiopoda) em uma planície de inundação Neotropical, Brasil.

Abstract

Biodiversity plays a fundamental role in maintaining ecosystems, providing greater resistance and resilience to external impacts, in addition to ensuring a wide range of essential ecosystem services. In freshwater environments, cladocerans stand out as highly efficient filter feeders, playing a crucial role in the food web by mediating the transfer of matter and energy from primary producers to higher trophic levels. In this study, the genetic diversity of Diaphanosoma birgei Korinek, 1981 and Moina minuta Hansen, 1899, which occur in the Upper Paraná River floodplain, was investigated using a fragment of the mitochondrial gene Cytochrome c Oxidase subunit I (COI). The results were used for comparison with sequences available in the BOLD Systems Version 4 and GenBank® databases. Using the maximum likelihood method (HKY + G4 model) for cladogram construction and the Hapsolutely software with the median-joining algorithm for haplotype networks, it was observed that Brazilian populations of D. birgei did not show significant genetic divergence among themselves. However, sequences from the Nearctic region exhibited significant genetic variation among the environments in which they occur and are genetically distant from the Brazilian haplotype, suggesting that D. birgei constitutes a species complex. Based on this result, a morphological analysis and a climatic niche overlap analysis were conducted, culminating in the description of Diaphanosoma sp. nov., a new species for the Neotropical region within the D. birgei complex. The cladograms indicated that the Brazilian specimens of Diaphanosoma sp. nov. formed a sister group with D. cf. heberti, showing genetic divergence from Northern Hemisphere specimens. For M. minuta, which has no available sequence records for comparison in the databases, the individual found and sequenced from the Fechada lagoon showed a large genetic distance from other species of the genus, ranging from 13.9 to 21.1%. The results revealed a marked genetic differentiation between the cladocerans sequenced in Brazil and those available globally, with an emphasis on Old World records. This indicated a new perspective on the evolutionary process of the genus Moina. These findings reinforce the need for further molecular studies and conservation measures to preserve the genetic diversity of these ecologically important organisms.