Bernhardt, P. | Search bioRxiv

bioRxiv2021

Temporal and Spatial Niche Partitioning of Bumblebee Species (Apidae: Bombus) on a Himalayan Mountain

BackgroundBumblebees are essential pollinators in many ecosystems. To maintain such ecosystem functions, bumblebee diversity remains an important concern. We measured abundance and diversity of bumblebee species along an elevational gradient over three flowering seasons. We hypothesized that co-occurring bumblebees partition niches over time and space. MethodsWe sampled bumblebees at six different meadows along Yulong Snow Mountain (Yunnan, SW China), a region known for high bumblebee diversity, over summer months (2017 - 2019). We analyzed the standardized abundances of the workers from different bumblebee species over 11 weeklong periods. We also analyzed the standardized abundances of the workers of each species at each of the six different meadows. ResultsClear patterns of temporal niche partitioning were most apparent for the two, dominant species, B. friseanus and B. lepidus. Spatial niche partitioning was evident for rarer species which tended to be most abundant at lower elevations. ConclusionsTemporal and spatial niche partitioning are among two of the ways that bumblebee diversity is maintained on Yulong Snow Mountain. This has future implications if changing climate conditions disrupt partitioning leading to increased interspecific competition.

ecology↗

bioRxiv2021

Cypripedium wardii (Orchidaceae) employs pseudopollen with both reward and deception to attract both flis and bees as pollinators

O_LIFlowering plants always attract animals providing rewards or deceptive signals to gain reproductive success. However, there is no well-documented reporting about a pollination mechanism with both rewards and deceptive signals by a same object. We found Cypripedium wardii flowers seem to attract visitors by the white pseudopollenlike trichomes on labella in our preliminary field observation. C_LIO_LITo explore the pollination mechanism of Cypripedium wardii, especially, the ecological function of the pseudopollen-like trichomes, we conducted field observations, analyses of the traits of visitors and flowers, and breeding system experiments. C_LIO_LIThe white trichomes composed by multicellular moniliform hairs on the floral labella played a crucial role to attract pollinators, causing a high natural fruit set ratio in C. wardii. We established the direct connection of the white trichomes and real pollen. C_LIO_LIWe propose that flowers of C. wardii provide pseudopollen to attract suitable bees and hoverflies as pollinators. And our evidence indicate that the pseudopollen owns both deceptive and rewarding ecological functions. Our study provide a clear pollination mechanism with both rewards and deceptive signals by a same object in angiosperm for the first time. However, an inbreeding depression seem to be caused by this strategy. And we speculated that the pollen mimicry strategy with both rewarding and deceptive functions in C. wardii may be an adaptation to the habitat fragmentation of this species to gain a reproductive assurance. C_LI

plant biology↗