@article{SponslerRequierKallniketal.2022,
  author    = {Sponsler, Douglas B. and Requier, Fabrice and Kallnik, Katharina and Classen, Alice and Maihoff, Fabienne and Sieger, Johanna and Steffan-Dewenter, Ingolf},
  title     = {Contrasting patterns of richness, abundance, and turnover in mountain bumble bees and their floral hosts},
  series = {Ecology},
  volume    = {103},
  journal   = {Ecology},
  number    = {7},
  doi       = {10.1002/ecy.3712},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-287199},
  year      = {2022},
  abstract  = {Environmental gradients generate and maintain biodiversity on Earth. Mountain slopes are among the most pronounced terrestrial environmental gradients, and the elevational structure of species and their interactions can provide unique insight into the processes that govern community assembly and function in mountain ecosystems. We recorded bumble bee-flower interactions over 3 years along a 1400-m elevational gradient in the German Alps. Using nonlinear modeling techniques, we analyzed elevational patterns at the levels of abundance, species richness, species β-diversity, and interaction β-diversity. Though floral richness exhibited a midelevation peak, bumble bee richness increased with elevation before leveling off at the highest sites, demonstrating the exceptional adaptation of these bees to cold temperatures and short growing seasons. In terms of abundance, though, bumble bees exhibited divergent species-level responses to elevation, with a clear separation between species preferring low versus high elevations. Overall interaction β-diversity was mainly caused by strong turnover in the floral community, which exhibited a well-defined threshold of β-diversity rate at the tree line ecotone. Interaction β-diversity increased sharply at the upper extreme of the elevation gradient (1800-2000 m), an interval over which we also saw steep decline in floral richness and abundance. Turnover of bumble bees along the elevation gradient was modest, with the highest rate of β-diversity occurring over the interval from low- to mid-elevation sites. The contrast between the relative robustness bumble bee communities and sensitivity of plant communities to the elevational gradient in our study suggests that the strongest effects of climate change on mountain bumble bees may be indirect effects mediated by the responses of their floral hosts, though bumble bee species that specialize in high-elevation habitats may also experience significant direct effects of warming.},
  language  = {en}
}
@article{NjovuSteffanDewenterGebertetal.2021,
  author    = {Njovu, Henry K. and Steffan-Dewenter, Ingolf and Gebert, Friederike and Schellenberger Costa, David and Kleyer, Michael and Wagner, Thomas and Peters, Marcell K.},
  title     = {Plant traits mediate the effects of climate on phytophagous beetle diversity on Mt. Kilimanjaro},
  series = {Ecology},
  volume    = {102},
  journal   = {Ecology},
  number    = {12},
  doi       = {10.1002/ecy.3521},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257343},
  year      = {2021},
  abstract  = {Patterns of insect diversity along elevational gradients are well described in ecology. However, it remains little tested how variation in the quantity, quality, and diversity of food resources influence these patterns. Here we analyzed the direct and indirect effects of climate, food quantity (estimated by net primary productivity), quality (variation in the specific leaf area index, leaf nitrogen to phosphorus and leaf carbon to nitrogen ratio), and food diversity (diversity of leaf traits) on the species richness of phytophagous beetles along the broad elevation and land use gradients of Mt. Kilimanjaro, Tanzania. We sampled beetles at 65 study sites located in both natural and anthropogenic habitats, ranging from 866 to 4,550 m asl. We used path analysis to unravel the direct and indirect effects of predictor variables on species richness. In total, 3,154 phytophagous beetles representing 19 families and 304 morphospecies were collected. We found that the species richness of phytophagous beetles was bimodally distributed along the elevation gradient with peaks at the lowest (˜866 m asl) and upper mid-elevations (˜3,200 m asl) and sharply declined at higher elevations. Path analysis revealed temperature- and climate-driven changes in primary productivity and leaf trait diversity to be the best predictors of changes in the species richness of phytophagous beetles. Species richness increased with increases in mean annual temperature, primary productivity, and with increases in the diversity of leaf traits of local ecosystems. Our study demonstrates that, apart from temperature, the quantity and diversity of food resources play a major role in shaping diversity gradients of phytophagous insects. Drivers of global change, leading to a change of leaf traits and causing reductions in plant diversity and productivity, may consequently reduce the diversity of herbivore assemblages.},
  language  = {en}
}