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Keywords:

species discovery, pisces, adaptive radiation, cytochrome c oxidase subunit I, DNA barcoding, identification, Science & Technology, Life Sciences & Biomedicine, Biochemistry & Molecular Biology, Ecology, Evolutionary Biology, Environmental Sciences & Ecology, identification, FRESH-WATER FISHES, PHYLOGENETIC-RELATIONSHIPS, EVOLUTIONARY PROCESSES, LINEAGE, IDENTIFICATION, SPECIATION, TAXONOMY, DIVERSIFICATION, SYSTEMATICS, INVENTORY, Adaptation, Biological, Animals, Cichlids, DNA Barcoding, Taxonomic, Electron Transport Complex IV, Fishes, Genetics, Population, Lakes, Phylogeography, Sequence Analysis, DNA, Tanzania, 06 Biological Sciences

Abstract:

We obtained 398 cytochrome c oxidase subunit I barcodes of 96 morphospecies of Lake Tanganyika (LT) cichlidsfrom the littoral zone. The potential of DNA barcoding in these fishes was tested using both species identificationand species delineation methods. The best match (BM) and best close match (BCM) methods were used to evaluatethe overall identification success. For this, three libraries were analysed in which the specimens were categorizedinto Operational Taxonomic Units (OTU) in three alternative ways: (A) morphologically distinct, including unde-scribed, species, (B) valid species and (C) complexes of morphologically similar or closely related species. Forlibraries A, B and C, 73, 73 and 96% (BM) and 72, 70 and 94% (BCM) of the specimens were correctly identified. Addi-tionally, the potential of two species delineation methods was tested. The General Mixed Yule Coalescent (GMYC)analysis suggested 70 hypothetical species, while the Automatic Barcode Gap Discovery (ABGD) method revealed115 putative species. Although the ABGD method had a tendency to oversplit, it outperformed the GMYC analysisin retrieving the species. In most cases where ABGD suggested oversplitting, this was due to intraspecific geographi-cal variation. The failure of the GMYC method to retrieve many species could be attributed to discrepancies betweenmitochondrial gene trees and the evolutionary histories of LT cichlid species. Littoral LT cichlids have complex evo-lutionary histories that include instances of hybridization, introgression and rapid speciation. Nevertheless,although the utility of DNA barcoding in identification is restricted to the level of complexes, it has potential forspecies discovery in cichlid radiations.