Touch-sensitive stamens enhance pollen dispersal by scaring away visitors
- Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, China
- Department of Biology, Washington University, United States
Figures
Figure 1 with 2 supplements
Flower traits, foraging behavior of visitors, and manipulations of stamen movements in Berberis julianae, which has stamens characterized by a touch-sensitive rapid movement toward the flower center.
The major pollinators, workers of Apis cerana (A), and a long-tongued bee, Habropoda sichuanensis (B), sucking nectar while their tongues (arrow) may contact filaments, anthers, and/or stigmas. …
Figure 1—figure supplement 1
Flower manipulations and experimental floral arrays in Berberis julianae.
(A) An SMA flower with its pedicel fixed above 10 μL of alcohol. (B) An experimental array with stamens-mobile (SM), stamens-immobilized (SI), and filament-damaged (FD) flowers under enclosed …
Figure 1—figure supplement 2
Habit, floral traits, developing berries, and feeding behavior of flower visitors in three Berberidaceae species whose stamens are touch-sensitive.
Bird’s eye view of a flowering individual in an open habitat (A) and an infructescence (B) of Berberis julianae in Sichuan. A hawkmoth (C) and a bumblebee worker (Bombus friseanus Skorikov, 1933) (D)…
Figure 2
Fruit and seed set (mean ± Standard Error) after four pollination treatments in Berberis julianae.
Different letters beside mean values indicate significant differences among the four treatments under a generalized linear model (GLM). Fruit set differed significantly (Wald χ2 = 34.598, p<0.001, …
Figure 3
Visitation rates (A, C) and handling times (B, D) of Apis cerana in four treatments of flowers of Berberis julianae.
Stamens mobile (SM, controls), stamens immobilized (SI), natural flowers in a fixed position above alcohol (SMA), and flowers with their filaments damaged (FD) so that the stamens became immobile …
Figure 4
Comparisons of six parameters (mean ± Standard Error) in Berberis julianae to examine the effects of stamen movements on insect visitor foraging behavior and their roles in pollination.
The major pollinator, Apis cerana, was studied in 2020 and 2021 under open pollination (far left) and enclosed conditions (set-up shown in Figure 1—figure supplement 1 and Video 3), whereas the …
Figure 5 with 1 supplement
Effects of stamen forward-snapping on pollen placement on the pollinator body and pollen deposition on stigmas after single visits by Apis cerana (A, C) and the anthophorid bees (B, D).
Numbers of pollen grains placed on bees’ tongues during a single visit were significantly higher when stamens were mobile (SM) than when stamens were experimentally immobilized (SI) (A, B). Numbers …
Figure 5—figure supplement 1
Foraging behavior of Apis cerana and its effect on pollination in Berberis julianae flowers with experimentally immobilized stamens and controls in 2020 and 2021 including visits to floral arrays per flower (A, B), insect handling time per flower (C, D), and pollen removal (E, F), pollen deposition (G, H) and pollen transfer efficiency (I, J) by single visits.
Mean and SEs (standard-error bars) are presented, with different lowercase letters indicating significant differences between control (SM) and stamen-immobilized (SI) flowers.
Figure 6 with 1 supplement
Number of stained pollen grains deposited on the stigmas from control flowers with mobile stamens (open circles) and from flowers with experimentally immobilized stamens (closed circles) in Berberis julianae.
Mean pollen number and SEs (numbers of flowers with stained pollen deposition/total number of sampled flowers of pollen recipients) are given for treated and control flowers in each of four trials (A…
Figure 6—figure supplement 1
Number of stained pollen grains deposited on the stigmas from control flowers with mobile stamen (open circles) and from flowers with experimentally immobilized stamens (closed circles) in Berberis jamesiana.
Mean pollen number (n = 100 flowers) and SEs are given in each of four trials (A–D). Each pollen-tracking test involved 100 pollen-recipient flowers, but the 70 additional flowers not receiving any …
Videos
Video 1
Stamens of Berberis julianae become touch-insensitive after the flower pedicels had been immersed in 75% alcohol for 35 min.
Video 2
Stamens of Mahonia bealei become touch-insensitive after the flower pedicels had been immersed in 75% alcohol for 30 min.
Video 3
Under enclosed conditions (Figure 1—figure supplement 1D), individual syrphid flies (Meliscaeva spec.) took up nectar from a Berberis julianae flower with immobilized stamens for much longer, giving them time to touch four stamens, while leaving more quickly and touching only two stamens in a control flower with mobile stamens.
Additional files
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Supplementary file 1
Floral traits (mean ± SE) and duration of stamen movements in Berberis jamesiana, B. julianae, B. forrestii, and Mahonia bealei.
- https://cdn.elifesciences.org/articles/81449/elife-81449-supp1-v1.docx
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Supplementary file 2
Foraging behaviors of two types of major insect visitors to Berberis julianae.
Behaviors of the bees and flies visiting Berberis julianae, focusing on visitation rates (visits per flower per hour, mean ± SE), visits per flower, handling time, number of stamens touched, nectar volume remaining per flower, pollen grains removed, pollen grains deposited, and pollen transfer efficiency.
- https://cdn.elifesciences.org/articles/81449/elife-81449-supp2-v1.docx
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Supplementary file 3
G-test of independence confirming that Berberis julianae flowers with mobile stamens (SM flowers) donated pollen to more recipient flowers at three distance classes than did flowers with experimentally immobilized stamens (SI flowers).
- https://cdn.elifesciences.org/articles/81449/elife-81449-supp3-v1.docx
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Supplementary file 4
G-test of independence confirming that Berberis jamesiana flowers with mobile stamens (SM flowers) donated pollen to more recipient flowers at two distance classes than did flowers with experimentally immobilized stamens (SI flowers).
- https://cdn.elifesciences.org/articles/81449/elife-81449-supp4-v1.docx
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Supplementary file 5
Concentrations of berberine (mean ± SE) in different tissues of Berberis julianae under generalized linear models.
- https://cdn.elifesciences.org/articles/81449/elife-81449-supp5-v1.docx
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MDAR checklist
- https://cdn.elifesciences.org/articles/81449/elife-81449-mdarchecklist1-v1.docx
