Diet in phenotypically divergent sympatric species of African weakly electric fish (genus: Campylomormyrus) – a hybrid capture/NGS metabarcoding approach

Abstract

Ecological speciation within the mormyrid genus Campylomormyrus resulted in sympatric species exhibiting divergence in their feeding apparatus and electric organ discharge (EOD). This study provides direct evidence to support the suggested ecological speciation scenario that Campylomormyrus radiation is caused by an adaptation to different food sources. We performed diet assessment of sympatric Campylomormyrus species with markedly different snout morphologies and EODs using hybrid capture/NGS DNA metabarcoding of their stomach contents. Our approach allowed for high taxonomic resolution of prey items, including benthic invertebrates, allochthonous invertebrates, and vegetation. Comparisons of the diet compositions using quantitative measures and diet overlap indices revealed that all species are able to exploit multiple food niches in their habitats, i.e. fauna at the bottom, the water surface, and the water column. The major part of the diet is larvae of aquatic insects, such as dipterans, coleopterans, and trichopterans, known to occur in holes and interstitial spaces of the substrate. The results showed that different snout morphologies and the associated divergence in the EOD translate into different prey spectra. This suggests that the diversification in EOD and the morphology of the feeding apparatus is under functional adaptation.

Diet in phenotypically divergent sympatric species of African weakly electric fish (genus: Campylomormyrus)—A hybrid capture/HTS metabarcoding approach

“…The sequencing for all samples generated 6.9Gb raw sequencing data of FASTQ formatted reads. The sequence data have been submitted to the GenBank SRA database under accession number PRJNA1041468 (Amen, 2023a). The total number of raw sequences from the 27 stomach samples is 19,531,074, ranging from 19,226 to 867,093 per individual sample (Mean = 335,020; SD = 234,220).…”

“…The sequencing for all samples generated 6.9Gb raw sequencing data of FASTQ formatted reads. The sequence data have been submitted to the GenBank SRA database under accession number PRJNA1041468 (Amen, 2023a). The total number of raw sequences from the 27 stomach samples is 19,531,074, ranging Additionally, a series of negative (library and DNA extraction) and positive controls, which were treated identically to other samples from initial processing through library preparation, was included to further filter the data and validate the obtained taxa.…”