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Bimodal activity of diurnal flower visitation at high elevation


Xu, Xin et al. (2023), Bimodal activity of diurnal flower visitation at high elevation, Dryad, Dataset,


Successful pollination in animal-pollinated plants depends on the temporal overlap between flower presentation and pollinator foraging activity. Variation in the temporal dimension of plant-pollinator networks has been investigated intensely across flowering seasons. However, over the course of a day, the dynamics of plant-pollinator interactions may vary strongly due environmental fluctuations. It is usually assumed there is a unimodal, diurnal, activity pattern, while alternative multi-modal types of activity patterns are often neglected and deserve greater investigation. Here, we quantified the daily activity pattern of flower visitors in two different habitats contrasting high elevation meadows versus forests in Southwest China to investigate the role of abiotic conditions in the temporal dynamics of plant-pollinator interactions. We examined diurnal activity patterns for the entire pollinator community. Pollinator groups may differ in their ability to adapt to habitats and abiotic conditions, which might be displayed in their patterns of activity. We hypothesized, that 1) pollinator communities show multi-modal activity patterns, 2) patterns differ between pollinator groups and habitat types, and 3) abiotic conditions explain observed activity patterns. In total, we collected 4988 flower visitors belonging to six functional groups. There was a bimodal activity pattern when looking at the entire pollinator community, and in five out of six flower visitor groups (exempting solitary bees). Bumblebees, honeybees, dipterans, lepidopterans, and other insects showed activity peaks in the morning and afternoon, whereas solitary bees were most active at midday. Activity of all six pollinator groups increased as solar radiation increased and then decreased after reaching a certain threshold. Our findings suggest that in habitats at higher elevations, a bimodal activity pattern of flower visitation is commonly employed across most pollinator groups that are diurnal foragers. This pattern may be caused by insects avoiding overheating due to elevated temperatures when exposed to high solar radiation at midday. 


Strategic Priority Research Program of the Chinese Academy of Sciences, Award: XDB31000000

National Natural Science Foundation of China, Award: 32071670

National Natural Science Foundation of China, Award: 31700361

Natural Science Foundation of Yunnan Province, Award: 2019FB035

Yunlin Scholarship of Yunnan Province, Award: YLXL20170001