Abstract
Highly spread through the Amazon River basin, Prochilodus nigricans have had its taxonomic validity recently questioned, when genetic differences between Western and Eastern Amazon populations from the Brazilian shield were detected. This area has been seeing as a region of high ichthyofaunal diversity and endemism, in which the hybrid origin of the Tapajós River basin has been raised. In this paper, we report a new molecular lineage within P. nigricans of Tapajós River, highlighting this region still hides taxonomically significant diversity. Haplotype networks were reconstructed using the mitochondrial COI and ATP6/8 markers, which were also used to calculate genetic distances among clusters. We additionally conducted a delimiting species approach by employing a Generalized Mixed Yule-Coalescent model (GMYC) with COI sequences produced here, and previous ones published for individuals sampled across the Amazon River basin. In addition to the genetic differentiation within P. nigricans, our findings favor the hypothesis of hybrid origin of the Tapajós River basin and reaffirm the importance of studies aiming to investigate hidden diversity to address taxonomic and biogeographic issues, that certainly benefit better biodiversity conservation actions.
Highlights
Freshwater ecosystems are exposed to great human-promoted impacts and transformations [1], making studies focusing on the discovery and comprehension of the extent biodiversity crucial for their conservation [2,3]
With over 5,160 freshwater fish species described in the South American rivers, this region harbors one-third of fish species of the entire planet, and the expectation is that this number is 42% higher [4]
Taking into account the importance of DNA-based approaches for delimiting species [5,19,20,21,22], we analyzed P. nigricans throughout the Tapajos River basin to investigate if this hydrographic system still hides taxonomically significant diversity for this important fishery resource, which represents the third most captured taxon in the Brazilian Amazon River basin [23]
Summary
Freshwater ecosystems are exposed to great human-promoted impacts and transformations [1], making studies focusing on the discovery and comprehension of the extent biodiversity crucial for their conservation [2,3]. Considering the Brazilian Shield is an underestimated region of high ichthyofaunal diversity and endemism [18], and the previously reported Prochilodus phylogeny [15,16] included few individuals from Tapajos River, this basin still requires a more extensive sampling In this sense, and taking into account the importance of DNA-based approaches for delimiting species [5,19,20,21,22], we analyzed P. nigricans throughout the Tapajos River basin to investigate if this hydrographic system still hides taxonomically significant diversity for this important fishery resource, which represents the third most captured taxon (in tons) in the Brazilian Amazon River basin [23]. Our data raised a new Molecular Operational Taxonomic Units (MOTUs) within P. nigricans and certainly contributes for better estimating of biodiversity into the taxon
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