Phenological turnover matters when making trait-based predictions of plant-pollinator interactions
Data files
Jul 07, 2025 version files 368.86 KB
Abstract
Understanding the processes determining species’ interactions is key to predicting and safeguarding ecological networks under rapid environmental change. One approach to estimating interactions is to use morphologies of taxa interacting across trophic levels to reveal suites of traits they are more likely to interact with (i.e. a morphological trait niche). Previous work studying these morphological trait niches has typically used interactions between species that are pooled in space and time. However, species assemblages, and the traits of individuals within species, can change across even small landscapes over a season, leading to morphological trait space being dynamically reshaped. Therefore, it is unclear how morphological trait turnover affects our inferences of trait niches, and our ability to answer this is in part limited by a lack of individual-level trait data. Here, we directly address this by studying a montane Arctic plant-pollinator community over five growing seasons (>1,300 hours of fieldwork). Specifically, we linked every recorded plant-bumblebee interaction with the traits of the bee individual involved (n = 1,150), to investigate 1) whether plant taxa (n = 10) exhibited bee trait niches by interacting with specific regions of multidimensional trait space of visiting bumblebees, and 2) how our inference of these trait niches was affected by considering bumblebee trait turnover and plant taxon turnover over space and time. When we did not consider turnover (i.e., interactions in space and time were pooled), plant taxa demonstrated bee trait niches. However, we next considered how bee trait space was reshaped over the elevational and seasonal gradient (for example, with the emergence of different castes), and how this reshaping co-occurred with different spatiotemporal ranges of the plant taxa. From this, we found plant taxa no longer interacted with a smaller area of bee community trait space than expected by chance (i.e. no longer showed a bee trait niche), and that seasonal reshaping of bee trait space was the primary driver of this trend. Overall, in highly dynamic systems, like the Arctic, overlooking community turnover could mask and even overestimate the ability of morphology to explain interactions. Hence, determining how morphological traits of individual interaction partners are in phenological synchrony at localised scales will be fundamental to understanding the role morphology plays in underpinning plant-pollinator interactions.
Dataset DOI: 10.5061/dryad.t76hdr8cg
Description of the data and file structure
The data are composed of three files:
- Working_spreadsheet_ITV_1819212223_v2.xlsx – These data were collected from observations of plant-bumblebee interactions on Mt. Nuolja in Sweden in 2018, 2019, 2021, 2022, and 2023. Each bee that was caught was photographed in the field, and from these photos, trait measurements were made. These measurements are also present in the dataset, in both raw and scaled forms, and then when summarized into PCA axes.
- Different_phenology_ranges_using_phenology_data.csv – These were collected by the Nuolja phenology project, in which phenophases of the plant community are recorded along a 3.4 km transect. The data in this file represent the onset and end of flowering (in day of year) each year.
- Different_elevation_ranges_using_phenology_data.csv – These were collected by the Nuolja phenology project, in which phenophases of the plant community are recorded along a 3.4 km transect. The data in this file represent the ranges that each species was detected along the transect. The values represent the sub-transects present (spaced 45 m apart).
Files and variables
File: Different_elevation_ranges_using_phenology_data.csv
Variables
- Year: The year the data were collected.
- Species: The plant taxon for which the data were collected.
- Yr_sp: This is a combination of the year the data were collected, and the plant taxon that the data corresponds to.
- Min_elevation_all: This is the lowest pole (corresponding to lowest elevation) on the transect for which this taxon was observed flowering that year.
- Max_elevation_all: This is the highest pole (corresponding to highest elevation) on the transect for which this taxon was observed flowering that year.
- Min_elevation_595: This is the lowest pole (corresponding to lowest elevation) on the transect for which this taxon was observed flowering that year. However, this value was attained after removing the first and last 5% of data points (to avoid outliers affecting the elevational range of each plant taxon).
- Max_elevation_595: This is the highest pole (corresponding to highest elevation) on the transect for which this taxon was observed flowering that year. However, this value was attained after removing the first and last 5% of data points (to avoid outliers affecting the elevational range of each plant taxon).
File: Different_phenology_ranges_using_phenology_data.csv
Variables
- Year: The year the data were collected.
- Species: The plant taxon for which the data were collected.
- Yr_sp: This is a combination of the year the data were collected and the plant taxon that the data corresponds to.
- Earliest_flowering_all: This is the earliest day of the year that the taxon was observed flowering on the transect that year.
- Latest_flowering_all: The latest day of the year that the taxon was observed flowering on the transect that year.
- Earliest_flowering_595: This is the earliest day of the year that the taxon was observed flowering on the transect that year. However, this value was attained after removing the first and last 5% of data points (to avoid outliers affecting the phenological range of each plant taxon).
- Latest_flowering_595: The latest day of the year that the taxon was observed flowering on the transect that year. However, this value was attained after removing the first and last 5% of data points (to avoid outliers affecting the phenological range of each plant taxon).
File: Working_spreadsheet_ITV_1819212223_v2.xlsx
Variables
- Sample_No: A unique identifier for each bee in the dataset.
- Year: The year the data was collected.
- Date: The date on which the survey of bee-plant interactions occurred.
- DOY: The day of year (derived from the date) on which the survey of bee-plant interactions occurred.
- Month: The month during which the survey of bee-plant interactions occurred.
- Sub_Transect: The survey plot along Mt. Nuolja in Sweden, in which we conducted bumblebee observations. The values are (from lowest to highest elevation plots): 04-05, 09-10, 21-22, 25-26, 29-30, 32-33, 35-36, 41-42, 45-46, 47-48, 60-61, 65-66, and 73-74.
- Sub_Transect_numbered: This numbers the "Sub-Transect" in order from lowest to highest elevation, i.e., 04-05 is 1, and 73-74 is 13.
- Vegetation_Zone: This identifies the vegetation zone on Mt. Nuolja in which the survey plot is situated. Vegetation zone A corresponds to old birch forest and contains survey plots 04-05, 09-10, and 21-22. Zone B is a young, newly established birch forest, containing survey plots 25-26 and 29-30. Zone C is shrub willow, containing plots 32-33, 35-36, and 41-42. Zone D is an herbaceous meadow, containing plots 45-46 and 47-48. Finally, zone E is Arctic dwarf shrub and heath, containing plots 60-61, 65-66, and 73-74.
- Altitude: The elevation of the survey plots in meters above sea level.
- Activity_Flying_Foraging: During a survey, if we saw a bumblebee, we noted if it was flying or foraging. N.B. This dataset has been filtered to only include foraging bees.
- Catch_Y_N: During a survey, if we say a bumblebee, we would try to catch it, to photograph for trait measurements. We would note down if the bee was successfully caught (Y = yes, N = no). N.B. This dataset has been filtered to only include bees that we caught.
- Bombus_Species: The species identity of the bumblebee, based on morphological identification.
- Bombus_Species_Certainty: Bumblebee species identifications were given a confidence score (1 = not confident, 3 = confident). N.B. This dataset has been filtered to only include bees that we identified with a confidence score of 2 or greater.
- Caste_Assigned_CT: The caste of the bumblebee.
- Head_width_mm: The head width (i.e., the largest distance between distal surfaces of the eyes measured dorsally) of the bumblebee, measured from a photograph (in mm).
- ITD_mm: The intertegular distance of the bumblebee, measured from a photograph (in mm).
- Wing_length_mm: The wing length (i.e., the maximal distance between one forewing attachment point and the most distal point on that corresponding wing’s marginal cell) of the bumblebee, measured from a photograph (in mm).
- Corrected_Flower_Species_ID2: The plant taxon that we observed the bumblebee interacting with.
- Social_parasitic: Whether the bumblebee species is known to be parasitic (e.g. Bombus flavidus).
- Estimated_prementum_length_mm: The predicted prementum length of the bumblebee, estimated using a mixed-effects model, with their intertegular distance, species identity and caste as predictor variables.
- Species_caste: A variable combining bee species identity and caste.
- Tongue_scaled: Bumblebee prementum length after it has been centred and scaled (mean = 0, sd = 1).
- Head_scaled: Bumblebee head width after it has been centred and scaled (mean = 0, sd = 1).
- Wing_scaled: Bumblebee wing length after it has been centred and scaled (mean = 0, sd = 1).
- ITD_scaled: Bumblebee intertegular distance after it has been centred and scaled (mean = 0, sd = 1).
- Species_Caste: A variable combining bee species identity and caste.
- pca_axis1: The first PC axis after performing a PCA on the scaled bee trait measurements (i.e., columns: Tongue_scaled, Head_scaled, Wing_scaled, and ITD_scaled).
- pca_axis2: The second PC axis after performing a PCA on the scaled bee trait measurements (i.e., columns: Tongue_scaled, Head_scaled, Wing_scaled, and ITD_scaled).
- pca_axis3: The third PC axis after performing a PCA on the scaled bee trait measurements (i.e., columns: Tongue_scaled, Head_scaled, Wing_scaled, and ITD_scaled).
- pca_axis4: The fourth PC axis after performing a PCA on the scaled bee trait measurements (i.e., columns: Tongue_scaled, Head_scaled, Wing_scaled, and ITD_scaled).
- SD2_outliers: This column indicates whether any of the trait measurements for that bee were greater than two standard deviations away from the mean of the trait for the species & caste of that bee. Y = bee has traits greater than two standard deviations from the mean.
- SD3_outliers: This column indicates whether any of the trait measurements for that bee were greater than three standard deviations away from the mean of the trait for the species & caste of that bee. N.B. Bees with traits greater than three standard deviations have been filtered out from this dataset.
Code/software
These files can be opened with MS Excel.