Tongue-length was used as a response trait [ 13 ]. I expected bee communities on flowers requiring more specialized visitors to be more predictable after disturbance.
That is, I expected long-tongued bees could access all flowers, so would continue to visit plots without tube flowers, while short-tongued bees would avoid manipulated plots where open flowers with shallowly accessible nectar were removed. Half of each of the first two plots was manipulated, one with open flowerheads removed and the other with tube flowers removed. The other half of each was kept for control.
The third, a control, was placed at least 7 m away, in case manipulations caused changes in floral choices in immediately adjacent areas. Only flowers or flowerheads were removed. Manipulations were compared with co-temporal controls rather than before—after e.
Coto de Gomariz 'The Flower And The Bee' Red
Figure 1. Experimental design. Drawings by the author. Flower species. I observed bee visits in July within a day of floral manipulation, between Each plot was observed for an hour, one half-hour per half-plot. The number and species of flowers visited were recorded. Observations, timed with a stopwatch, started when a bee landed on a flower and ended when the bee left the plot. To allow natural foraging, bees were not captured. I tested bee sampling completeness with species accumulation curves pooled by replicate field and treatment plot using R package BiodiversityR software R v.
Interaction matrices were constructed with interaction weights in seconds the bee visited that flower at row—column intersections. To do so, bees uniquely associated with open and tube flowers were deleted from their respective adjacent and distant control matrices. Function vegdist in R package vegan was used to calculate Jaccard's and Chao's dissimilarity among the predicted, measured and control plot bee communities Chao corrects for unseen species; see electronic supplementary material, Methods [ 19 ].
The dissimilarity between the two halves of the distant controls provided an estimate of background community heterogeneity. Dissimilarity values were compared with paired Wilcoxon tests. To examine the proportion of long-tongued versus short-tongued bees in each community [ 13 ], I used generalized linear mixed-effects models GLMMs with a binomial error and a logit link R package lme4 , function glmer [ 20 ].
I was interested in whether the trait differed between treatments, and whether manipulated communities differed from predictions. The first model compared measured communities only and the manipulation was a fixed effect. The second model compared the measured and predicted communities under each manipulation, and included the interaction between the manipulations and observed status measured or predicted. Field was a random effect in both models. I followed bees visiting flower heads during min, with a per-field average of 87 bees range 70— and flowerheads range — and per half-plot average of 14 bees simplified interaction networks, figure 1 b.
In all fields I observed Bombus total bees across all fields , green bees 72 , Halictus 52 and Lasioglossum 40 ; in four fields, A. Field-level accumulation curves quickly plateaued for fields and manipulations, suggesting well-sampled morphospecies electronic supplementary material, figure S1. Figure 2. Bee community results.
Left: Chao dissimilarity index; right: Jaccard. The y axis shows the proportion of long-tongued bees; all other bees short-tongued. Thus, the measured proportion of short- and long-tongued bees was not different from the predicted proportion. Generalized linear mixed models. Run with a binomial error and logit link; estimate is the proportion of bees in a manipulated patch with long tongues.
- Puzzle: Spot The Bee In The Flowers With This Optical Illusion?
- East Of The Sun And West Of The Moon (Mills & Boon Spice Briefs).
Given high bee diversity [ 5 ], accurately predicting species composition following disturbance will always be a challenge. But, this study accurately predicted the relative proportions of the bee community with ecologically relevant traits that continued to visit flowers in two different trait groups following floral manipulation.
This was true despite different predictability of the bee morphospecies identities that visited the two floral trait groups. If replicable over larger spatial and temporal scales, this strategy may allow estimates of ecological function. Thus, relative trait group composition may be more relevant for understanding ecosystem function.
This experiment thus sets the stage for longer-term, landscape-scale studies. In this study, each flower trait group was still available elsewhere in the field.
And the bee comes
Bees were slightly less faithful in manipulations, but maintained trait group partners overall. If floral trait compositions changed in entire fields or landscapes, bees might more drastically adapt their foraging patterns e. Contrary to my hypothesis, long-tongued bees were more faithful foragers instead of forming novel interactions.
Many long-tongued bees were also larger-bodied [ 13 ], so may be more competitive [ 8 ], or energetically requiring higher nectar volumes or qualities only provided here by tube flowers, explaining their underrepresentation on open flowers [ 14 ]. Continuing research on which traits allow reliable predictions and at which spatial and temporal scales they are predictive is a major challenge for trait-based network ecology.
Methods adhered to Yale University standards and required no permits. All raw data are available in electronic supplementary material, table S2.
I declare I have no competing interests. Funding provided by the Schiff Fund of Yale University. Thank you to Yale School Forests and A. Rzeznikiewicz of the Connecticut Audobon Society for field sites; R. Buchkowski, O. Schmitz, S. McArt and the Danforth laboratory for discussion; and B. Brosi and anonymous reviewers for invaluable comments. Large datasets are available through Biology Letters ' partnership with Dryad. Login to your account.
Forgot password? Keep me logged in. New User. Change Password. Because floral electric fields can change within seconds, this new sensory modality - electrostatic field detection- may facilitate rapid and dynamic communication between flowers and their pollinators.
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