DNA Barcoding in Neotropical Freshwater Fish Diversity

DNA barcoding employs a standardised fragment of the mitochondrial cytochrome c oxidase I gene to assign specimens to species and uncover hidden lineages. In the Neotropical region, one of the globe’s richest freshwater faunas, barcoding has revolutionised taxonomic practise by exposing cryptic diversity across major orders such as Characiformes and Siluriformes. By comparing intraspecific and interspecific genetic distances, researchers have detected overlooked species complexes, refined range boundaries and mapped patterns of endemism shaped by drainage evolution and Pleistocene climate shifts. Beyond pure taxonomy, barcode data underpin conservation strategies by enabling rapid biodiversity surveys in remote basins, guiding sustainable fisheries management and informing habitat restoration. Ongoing efforts aim to expand reference libraries, integrate multilocus approaches and resolve cases of introgression and incomplete lineage sorting that can confound single‐locus identification.

Research from Nature Portfolio

Recent studies have applied mitochondrial COI barcoding to the Hoplias malabaricus species complex, revealing multiple cryptic taxa within what was long treated as a single, widely distributed predator. Barcode index numbers delineate at least six genetically distinct subpopulations corresponding to separate river basins, each exhibiting high Fst values that reflect long‐term isolation. Phylogeographic reconstruction attributes lineage divergence and demographic expansions to Pleistocene river rearrangements and climate oscillations. This work not only clarifies the taxonomic status of a key characiform fish but also demonstrates how standardised barcode metrics can disentangle shallow and deep evolutionary splits in Neotropical ichthyofaunas.

DNA Barcoding in Neotropical Freshwater Fish Diversity publication trend

The graph below shows the total number of articles in dna barcoding in neotropical freshwater fish diversity across all publications each year (not limited to Nature Index journals).

Technical terms

DNA barcoding: A method for identifying species using a short, standardised segment of the mitochondrial genome, typically the cytochrome c oxidase I gene.

Cytochrome c oxidase I (COI): A mitochondrial enzyme gene widely used as the standard barcode marker for animals due to its appropriate evolutionary rate and universal primers.

Molecular operational taxonomic unit (MOTU): A cluster of DNA sequences delineated by genetic similarity thresholds, used as a proxy for species in molecular surveys.

Barcode Index Number (BIN): A unique identifier assigned to clusters of COI sequences in a reference database, facilitating consistent species‐level assignments.

Phylogeography: The study of the historical processes that shape the geographic distribution of genetic lineages within and among species.

References

1. Molecular Evidence Reveals Taxonomic Uncertainties and Cryptic Diversity in the Neotropical Catfish of the Genus Pimelodus (Siluriformes: Pimelodidae). Biology (2024).
2. DNA barcoding and phylogeography of the Hoplias malabaricus species complex. Scientific Reports (2022).
3. The DNA barcode reveals cryptic diversity and a new record for the genus Leporinus (Characiformes, Anostomidae) in the hydrographic basins of central northern Brazil. PeerJ (2023).
4. DNA Barcoding Reveals High Levels of Divergence among Mitochondrial Lineages of Brycon (Characiformes, Bryconidae). Genes (2019).