Gagliano, M. | Search bioRxiv

bioRxiv2023

Bioelectrical Synchronisation of Spruce Trees during aSolar Eclipse

Regular light-dark cycles greatly affect organisms, and events like eclipses induce distinctive physiological and behavioural shifts. While well-documented in animals, plant behaviour during eclipses remains largely unexplored. Here we monitored multiple spruce trees to assess their individual and collective bioelectrical responses to a solar eclipse. Trees anticipated the eclipse, synchronising their individual bioelectrical behaviour hours in advance. Older trees displayed greater anticipatory behaviour with early time-asymmetry and entropy increases, characteristic of memory dynamics in open dissipative systems such as trees. These results reveal a complex relationship between individual and collective tree behaviour, shaped by individual age and physiology as well as collective history and memory. This highlights the adaptive significance of synchrony and collective memory in plants, offering new insights on coordinated behaviours in nature. One Sentence SummaryTrees anticipate and respond collectively to a solar eclipse.

plant biology↗

bioRxiv2022

Mimicking orchids lure bees from afar with exaggerated ultraviolet signals

O_LIFlowers have many sensory traits to appeal to pollinators, including ultraviolet (UV) absorbing markings, which are well known for attracting bees at close proximity (e.g. < 1 m). While striking UV signals have been thought to attract pollinators also at greater distances of meters, how the signals impact the plant pollination success over distance remains unknown. Here we report the case of the Australian orchid Diuris brumalis, a non-rewarding species, pollinated by bees via mimicry of rewarding pea plant Daviesia decurrens. When distant from the pea plant, Diuris brumalis was hypothesized to enhance pollinator attraction by exaggerately mimicking the floral ultraviolet (UV) reflecting patterns of its model. C_LIO_LIBy experimentally modulating floral UV reflectance with a UV screening solution, we quantified the orchid pollination success at variable distance from the model plants. C_LIO_LIWe demonstrate that the deceptive orchid Diuris brumalis attracts bee pollinators by emphasizing the visual stimuli, which mimic the floral UV signalling of the rewarding model D. decurrens. Moreover, the exaggerated UV reflectance of D. brumalis flowers impacted pollinators visitation at an optimal distance from D. decurrens, and the effect decreased when orchids were too close or too far away from the model. C_LIO_LIOur findings show that salient UV flower signalling plays a functional role in visual floral mimicry, likely exploiting perceptual gaps in bee neural coding, and mediates the plant pollination success at much greater spatial scales than previously expected. C_LI

ecology↗