Conclusions
We analyzed stomach contents of wild-caught Campylomormyrus fish
using hybrid capture and subsequent HTS DNA metabarcoding. Despite of
the highly degraded nature of the dietary material, this approach
provided a picture of the overall diet of this genus and revealed
dietary diversity, relative to
divergent phenotypical traits (EOD and snout). Although standard
metabarcoding is technically less demanding and may be preferred for
analysis of stomach samples if DNA quality is sufficient (Deagle et al.
2006; Jarman et al. 2004), hybrid capture provides an alternative for
samples of progressed digestion and associated high DNA fragmentation.
Generally, hybrid capture and subsequent HTS has been found superior to
direct PCR amplification, when small fragment sizes are encountered, as
in aDNA (e.g., Paijmans et al. 2016) and sedaDNA (e.g., Krueger et al.
2021). Our results confirmed that Campylomormyrus species can
exploit multiple food niches in their habitats (fauna at the bottom, at
the water surface, and in the water column) to feed on benthic
invertebrates, allochthonous invertebrates, and vegetation. alpha and
beta dietary diversity were significantly associated with differences in
EOD duration and snout length. Divergence in these traits may constitute
functional adaptations to exploiting different food sources and
substrates and may underly the radiation and sympatric coexistence of
the numerous species of this genus.