Discovering Hidden Diversity of Characins (Teleostei: Characiformes) in Ecuador's Yasuní National Park.

Ramiro Barriga,Daniel Escobar-Camacho,Santiago R Ron

doi:10.1371/journal.pone.0135569

Ramiro Barriga, Daniel Escobar-Camacho + Show 1 more

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https://doi.org/10.1371/journal.pone.0135569

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Abstract

BackgroundManagement and conservation of biodiversity requires adequate species inventories. The Yasuní National Park is one of the most diverse regions on Earth and recent studies of terrestrial vertebrates, based on genetic evidence, have shown high levels of cryptic and undescribed diversity. Few genetic studies have been carried out in freshwater fishes from western Amazonia. Thus, in contrast with terrestrial vertebrates, their content of cryptic diversity remains unknown. In this study, we carried out genetic and morphological analyses on characin fishes at Yasuní National Park, in eastern Ecuador. Our goal was to identify cryptic diversity among one of the most speciose fish families in the Amazon region. This is the first time that genetic evidence has been used to assess the species content of the Napo Basin, one of the richest regions in vertebrate diversity.ResultsPhylogenetic analyses of partial mitochondrial 16S ribosomal RNA gene (∼600 pb) DNA sequences from 232 specimens of the family Characidae and its closest groups revealed eight candidate new species among 33 species sampled, representing a 24% increase in species number. Analyses of external morphology allowed us to confirm the species status of six of the candidate species.ConclusionsOur results show high levels of cryptic diversity in Amazonian characins. If this group is representative of other Amazonian fish, our results would imply that the species richness of the Amazonian ichthyofauna is highly underestimated. Molecular methods are a necessary tool to obtain more realistic inventories of Neotropical freshwater fishes.

Highlights

Species are the fundamental units in studies of biodiversity, community ecology, and evolutionary biology
Our results show high levels of cryptic diversity in Amazonian characins
If this group is representative of other Amazonian fish, our results would imply that the species richness of the Amazonian ichthyofauna is highly underestimated

Summary

Introduction

Species are the fundamental units in studies of biodiversity, community ecology, and evolutionary biology. Recent DNA-based studies suggest that tropical faunas contain a large proportion of undescribed species that have escaped detection in morphology based assessments [12–14] The discovery of this “cryptic diversity” (i.e., separate species that have been classified as a single nominal species because they are, at least superficially, morphologically indistinguishable [15]) suggests that a thorough biodiversity inventory cannot be achieved without modern techniques of species delimitation, specially the use of DNA sequence data. The Yasuní National Park is one of the most diverse regions on Earth and recent studies of terrestrial vertebrates, based on genetic evidence, have shown high levels of cryptic and undescribed diversity. Our goal was to identify cryptic diversity among one of the most speciose fish families in the Amazon region This is the first time that genetic evidence has been used to assess the species content of the Napo Basin, one of the richest regions in vertebrate diversity

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