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).