Data from: Insight into trophic niche differentiation in Labeobarbus (Cyprinidae) in the Luhoho Basin (Upper Congo Basin)

Mouth morphology plays a crucial role in determining the trophic ecology
of fish and sometimes underpins important lineage diversification.
Freshwater teleost fish species belonging to the
genus Labeobarbus, commonly found in Africa, exhibit intra- and
interspecific variation and differences in the lower jaw occurring within
and between species, respectively. Different phenotypes include a curved
U-shape (‘rubberlips’), a straight lower jaw (‘chiselmouth’) and an
intermediate morphology known as the smiling phenotype. In some cases,
smiling originates from hybridisation between chiselmouth and rubberlips.
However, the trophic relationships of different mouth morphologies in
the Labeobarbus taxa are still not well understood,
particularly in the Congo Basin. Understanding the trophic ecology
of Labeobarbus can enhance understanding of adaptive
processes in morphologically diverse lineages. This study aims to
investigate how differences in mouth morphology among
multiple Labeobarbus species in the Luhoho River (Upper
Congo Basin) link with different trophic niche uses. We combined
information from gut morphometry, gut contents and stable isotope analyses
on 202 fish specimens representing six species across four tributaries of
the Middle Luhoho. All approaches consistently revealed trophic niche
partitioning between chiselmouth and rubberlip species, respectively, more
herbivorous/detritivorous and more insectivorous on the omnivory spectrum.
In addition, trophic differences were also found between species within
each mouth phenotype. Interestingly, the trophic niche of the smiling
phenotype differed strongly from those of other phenotypes at all sites
except for L. paucisquamatus, for which the trophic niches
overlapped in Tchinganda. The pattern of trophic niche
of Labeobarbus suggests subtle strategies to partition feeding
resources when they occur across a narrow hydrographic scale.