@article{MaihoffFriessHoissetal.2023,
  author    = {Maihoff, Fabienne and Friess, Nicolas and Hoiss, Bernhard and Schmid-Egger, Christian and Kerner, Janika and Neumayer, Johann and Hopfenm{\"u}ller, Sebastian and B{\"a}ssler, Claus and M{\"u}ller, J{\"o}rg and Classen, Alice},
  title     = {Smaller, more diverse and on the way to the top: Rapid community shifts of montane wild bees within an extraordinary hot decade},
  series = {Diversity and Distributions},
  volume    = {29},
  journal   = {Diversity and Distributions},
  number    = {2},
  doi       = {10.1111/ddi.13658},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312126},
  pages     = {272-288},
  year      = {2023},
  abstract  = {Aim Global warming is assumed to restructure mountain insect communities in space and time. Theory and observations along climate gradients predict that insect abundance and richness, especially of small-bodied species, will increase with increasing temperature. However, the specific responses of single species to rising temperatures, such as spatial range shifts, also alter communities, calling for intensive monitoring of real-world communities over time. Location German Alps and pre-alpine forests in south-east Germany. Methods We empirically examined the temporal and spatial change in wild bee communities and its drivers along two largely well-protected elevational gradients (alpine grassland vs. pre-alpine forest), each sampled twice within the last decade. Results We detected clear abundance-based upward shifts in bee communities, particularly in cold-adapted bumble bee species, demonstrating the speed with which mobile organisms can respond to climatic changes. Mean annual temperature was identified as the main driver of species richness in both regions. Accordingly, and in large overlap with expectations under climate warming, we detected an increase in bee richness and abundance, and an increase in small-bodied species in low- and mid-elevations along the grassland gradient. Community responses in the pre-alpine forest gradient were only partly consistent with community responses in alpine grasslands. Main Conclusion In well-protected temperate mountain regions, small-bodied bees may initially profit from warming temperatures, by getting more abundant and diverse. Less severe warming, and differences in habitat openness along the forested gradient, however, might moderate species responses. Our study further highlights the utility of standardized abundance data for revealing rapid changes in bee communities over only one decade.},
  language  = {en}
}
@article{SponslerKallnikRequieretal.2022,
  author    = {Sponsler, Douglas and Kallnik, Katharina and Requier, Fabrice and Classen, Alice and Maihoff, A. Fabienne and Sieger, Johanna and Steffan-Dewenter, Ingolf},
  title     = {Floral preferences of mountain bumble bees are constrained by functional traits but flexible through elevation and season},
  series = {Oikos},
  volume    = {2022},
  journal   = {Oikos},
  number    = {3},
  doi       = {10.1111/oik.08902},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259653},
  year      = {2022},
  abstract  = {Patterns of resource use by animals can clarify how ecological communities have assembled in the past, how they currently function and how they are likely to respond to future perturbations. Bumble bees (Hymentoptera: Bombus spp.) and their floral hosts provide a diverse yet tractable system in which to explore resource selection in the context of plant-pollinator networks. Under conditions of resource limitation, the ability of bumble bees species to coexist should depend on dietary niche overlap. In this study, we report patterns and dynamics of floral morphotype preferences in a mountain bumble bee community based on ~13 000 observations of bumble bee floral visits recorded along a 1400 m elevation gradient. We found that bumble bees are highly selective generalists, rarely visiting floral morphotypes at the rates predicted by their relative abundances. Preferences also differed markedly across bumble bee species, and these differences were well-explained by variation in bumble bee tongue length, generating patterns of preference similarity that should be expected to predict competition under conditions of resource limitation. Within species, though, morphotype preferences varied by elevation and season, possibly representing adaptive flexibility in response to the high elevational and seasonal turnover of mountain floral communities. Patterns of resource partitioning among bumble bee communities may determine which species can coexist under the altered distributions of bumble bees and their floral hosts caused by climate and land use change.},
  language  = {en}
}