Genus-level biotic information as a surrogate for species-level
knowledge in SDMs
The interacting species had a higher contribution at genus taxonomic
level to the modelled species at finer resolutions (500 m and 1 km).
Pollinators generally visit closely related plants more often than would
be expected (Vamosi et al. 2014) and our results suggest that at finer
resolutions biotic interactions at genus level could adequately
substitute species level interactions. This might be due to similar
habitats occupied by host species and niche conservationism, observed
in, for example, higher plants (Prinzing et al. 2001), or it could also
imply that the genus records are dominated by the same host species at
these locations. Another possibility could indicate high quality habitat
for plants/hosts in general (Widhiono et al. 2016). Only a few of the
oligolectic bees are monolectic, as most oligolectic bees collect pollen
from more than one taxonomically related plant species (Cane 2020),
resulting in a dependency on multiple plant species in the same genus.
The similar biosynthetic pathways in related plants are associated with
similar nutritional values of their pollen (Ruedenauer et al. 2019),
which explains why plant genus is a good approximation of the biotic
interaction. The cleptoparasitic bees showed lower variable importance
of the interacting species at coarse resolutions at the genus level
compared to the interacting species at species level. It is likely that
this trend is related to a loss of information on a coarser scale, as
the contribution of the interacting species at genus level decreases as
the resolution decreases. A potential explanation for the higher
contribution of the host at species level is that cleptoparasitic bees
tend to become more specialized as the coevolution between a parasite
and its host often leads to specialization (Bogusch et al. 2006). It is,
therefore, no surprise that around a quarter of the European
cleptoparasitic bees parasitize on only one species (Bogusch et al.
2006).