RESUMO
Molecular tools have been employed to improve the knowledge about freshwater Neotropical fishes. Such approaches supporting studies of groups including species complexes such as Astyanax, one of the most diversified and taxonomically complex genus of the family Characidae. Here, we employed species delimitation analyses in four Astyanax species described for the upper Paraguaçu River basin, a drainage within Northeastern Mata Atlântica freshwater ecoregion with high endemism. We implemented single and multilocus approaches based on two mitochondrial and one nuclear markers. Cytochrome c Oxidase I sequences previously available for Astyanax species were also added to our dataset. The single locus analyses showed A. epiagos, A. rupestris, and A. aff. rupestris as different Molecular Operational Taxonomic Units (MOTUs), while A. brucutu and A. lorien were grouped. However, the multilocus approach distinguished these two species and showed congruence for the remaining single locus results. Astyanax aff. rupestris was separated into two MOTUs using both approaches, highlighting the need for an integrative taxonomic revision including A. aff. rupestris. These findings contribute to a better understanding of the diversity of this fish group in the upper Paraguaçu, identifying hidden diversity and reinforcing the relevance of this hydrographic system as a notable hotspot for ichthyofauna biodiversity endemism.(AU)
Ferramentas moleculares têm sido empregadas para melhorar o conhecimento sobre os peixes Neotropicais. Tais abordagens apoiam estudos de grupos que incluem complexos de espécies, como Astyanax, um dos gêneros mais diversificados e taxonomicamente complexos dentro da família Characidae. Neste estudo, nós empregamos análises de delimitação de espécies em quatro espécies de Astyanax recentemente descritas da bacia do alto rio Paraguaçu, uma drenagem dentro da ecorregião Mata Atlântica Nordeste que apresenta alto endemismo. Nós realizamos abordagens de loco único e multilocos baseadas em dois marcadores mitocondriais e um nuclear. Sequências de Citocromo c Oxidase I anteriormente disponíveis para espécies de Astyanax foram adicionadas ao nosso conjunto de dados. As análises de loco único mostraram A. epiagos, A. rupestris e A. aff. rupestris como diferentes Unidades Taxonômicas Operacionais Moleculares (MOTUs), enquanto A. brucutu e A. lorien foram agrupadas. Entretanto, a abordagem multilocos distinguiu estas duas espécies e mostrou congruência com os demais resultados das análises de loco único. Astyanax aff. rupestris foi separada em duas MOTUs usando ambas as abordagens, sugerindo a necessidade de uma revisão taxonômica integrativa incluindo A. rupestris e ambas A. aff. rupestris. Esses achados contribuem para uma melhor compreensão da diversidade desse grupo de peixes na bacia do rio Paraguaçu, identificando diversidade oculta e reforçando a relevância desse sistema hidrográfico como um notável hotspot de endemismo da biodiversidade da ictiofauna.(AU)
Assuntos
Animais , Doenças Endêmicas/veterinária , Characidae/genética , Variação Genética , BiodiversidadeRESUMO
In general, large mammal species with highly specialized feeding behavior and solitary habits are expected to suffer genetic consequences from habitat loss and fragmentation. To test this hypothesis, we analyzed the genetic diversity distribution of the threatened giant anteater inhabiting a human-modified landscape. We used 10 microsatellite loci to assess the genetic diversity and population structure of 107 giant anteaters sampled in the Brazilian Central-Western region. No genetic population structuring was observed in this region suggesting no gene flow restriction within the studied area. On the other hand, the moderate level of genetic diversity (Ho = 0.54), recent bottleneck detected and inbreeding (Fis, 0.13; p ≤ 0.001) signatures suggest potential impacts on the genetic variation of this Xenarthra. Additionally, a previous demographic reduction was suggested. Thus, considering the increased human-promoted impacts across the entire area of distribution of the giant anteater, our results can illustrate the potential effects of these disturbances on the genetic variation, allowing us to request the long-term conservation of this emblematic species.
RESUMO
The megadiversity of the neotropical ichthyofauna has been associated to recent diversification processes, reflecting in subtle or lacking morphological differentiation between species, challenging the classical taxonomic identification. Leporinus friderici occurs in several river basins of South America, and its nominal taxonomic validity has been questioned. Its wide distribution within the Brazilian Shield suggests that this species could be genetically structured among the hydrographic basins, despite a sharp morphological similarity. In this study, we performed phylogenetic analyses, based on three nuclear (recombination activating gene 1, RAG1, recombination activating gene 2, RAG2, and myosin heavy chain 6 cardiac muscle alpha gene, Myh6) and two mitochondrial (COI and Cytochrome b, Cytb) markers, in specimens morphologically similar to L. friderici and related species from different hydrographic basins in South America. Our phylogenetic tree identified four well-supported clades, which point out to the existence of taxonomic inconsistencies within this fish group. A clade named L. cf. friderici sensu stricto included eight Molecular Operational Taxonomic Units recently diversified in the Brazilian Shield basins. These results were also confirmed by a single-gene species delimitation analysis. It is suggested that this clade includes a species complex, characterizing taxonomic uncertainties. Another clade recovered only L. friderici from the Suriname rivers, validating this nominal species in its type locality. A third no-named clade, characterized by deeper species divergence, recovered five different nominal species interleaved with other undescribed forms previously also recognized as L. cf. friderici, indicating taxonomic errors. The fourth clade only included L. taeniatus. Our results showed a complex scenario involving the morphotype L. cf. friderici and allowed us to address aspects related to evolutionary diversification of this fish group and historical processes involved with, highlighting the importance of revealing hidden biodiversity for the taxonomy and conservationist action plans of these fish.