DOI: 10.5061/dryad.rr4xgxdkw
title: Diversified but not redundant: Upslope migrating bumble bees restructure pollination services to alpine plants

description: Climate-induced range shifts lead to novel interactions between resident
 and migrating species. Understanding the outcomes of such novel
 interactions can allow for informed predictions of the fates of ecological
 communities experiencing a warming climate. Long-term studies of
 ecological communities are rare, limiting our ability to understand how
 novel interactions under climate change affect community structure and
 function. Using bumble bee visitation data collected before and after the
 onset of accelerated anthropogenic global warming, we examined the impact
 of upslope bumble bee migration on an alpine plant-bumble bee community
 structure and pollination services. We predicted that an influx of
 competitors would result in higher pollination services through increased
 niche partitioning. Contrary to our predictions, our findings reveal a
 substantial reduction in potential pollination services to historically
 preferred host plants, despite an increase in resource partitioning by
 alpine bumble bees. Direct measures of foraging fidelity reveal a 351%
 increase in individuals carrying mixed pollen loads (from 27.4% to 96.1%
 of foragers), potentially affecting seed production in historically
 preferred plant species. Similarly, network size increased as bumble bees
 foraged from 22 novel alpine plant species. Network modularity increased,
 potentially enhancing network robustness to secondary extinctions despite
 increased competition between bumble bee species. In summary, our study
 underscores that climate-induced range shifts can restructure alpine
 communities and ecosystem services, potentially favoring colonizing
 species and their novel interaction partners. While alpine habitats may be
 refugia for subalpine organisms, the indirect effects of climate change on
 species interactions could compound direct effects of climate stress on
 specialist resident species.
description: # Diversified but not redundant: Upslope migrating bumble bees restructure
 pollination services to alpine plants Dataset DOI:
 [10.5061/dryad.rr4xgxdkw](10.5061/dryad.rr4xgxdkw) ## Description of the
 data and file structure Bumble bee-plant interaction data for two time
 periods (data collected by Macior in the 1960s and data collected by
 Miller-Struttmann and colleagues in the 2010s). Additional data on bumble
 bee tongue lengths, flower corolla/tube depths, and bumble bee corbicular
 pollen purity is also included. ### Files and variables #### File:
 Manuscript_Analyses_VM_NMS_May_2025.Rmd **Description:** R Markdown file
 with all analyses used for the *Oikos* publication.  #### File:
 Macior_alpine_female_visits.csv **Description:** Visitation network for
 alpine bumble bee-plant communities in the 1960s in the Front Range of the
 Colorado Rocky Mountains. Data from Macior 1974 in *Melanderia*. #####
 Variables * PLANT: plant species * Columns "appositus" to
 "suckleyi": number of *Bombus [species name]* females observed
 on flowers of each plant species #### File:
 bumblebee_alpine_visitation_network_present_front_range_females_mert.csv
 **Description:** Visitation network for alpine bumble bee-plant
 communities in the 2010s in the Front Range of the Colorado Rocky
 Mountains.  ##### Variables * Column 1 (unnamed in the file): plant
 species * Columns "appositus" to "sylvicola": number
 of *Bombus [species name]* females observed on flowers of each plant
 species #### File: NMS_NectarForagerWeb_Alpine_Workers.csv
 **Description:** Network data for nectar foragers only. ##### Variables *
 Column 1 (unnamed in the file): plant species * Columns
 "appositus" to "sylvicola": number of *Bombus [species
 name]* females observed on flowers of each plant species #### File:
 PastNetwork_withMert_BootstrapResults_NODF_Connect_Mod_H2_Robust.csv
 **Description:**  ##### Variables * Column 1 (unnamed in the file):
 identifier for bootstrapped network results (1,000 randomly sampled
 networks of the 1960s network to match the smaller size of the 2010s
 network) * wNODF: weighted nestedness (NODF) * w_connectance: weighted
 connectance * modularity: modularity * H2: specialization * LL_robust:
 robustness to secondary extinctions following a random extinction of plant
 species * HL_robust: robustness to secondary extinctions following a
 random extinction of pollinator species #### File:
 Bumble_bee_tongue_length_-_Macior_1974_Original.csv
 **Description:** Bumble bee tongue lengths reported by Macior. NAs are
 listed for bee species that were observed in the networks but that did not
 have tongue lengths measured by Macior.  ##### Variables * BB.SPECIES:
 bumble bee species * MEAN: mean worker tongue length * STANDARD.DEVIATION:
 mean standard deviation of tongue lengths * PAST.ALP.MODULE: module
 assignment of the bumble bee species in the 1960s network *
 PRES.ALP.MODULE: module assignment of the bumble bee species in the 2010s
 network #### File: All_Tongue_Lengths_LongData.csv **Description:**  #####
 Variables * Column 1 (unnamed in the file) * TL: simulated tongue length
 (randomly generated using the mean and standard deviation) * species:
 bumble bee species * module: module assignment * Era: the 1960s network or
 the 2010s network #### File:
 All_TubeDepths_LongData_Updated_10June2024.csv **Description:**  #####
 Variables * Column 1 (unnamed in the file) * TD: simulated tube
 depth (randomly generated using the mean and standard deviation) *
 species: plant species * module: module assignment * Era:  the 1960s
 network or the 2010s network #### File:
 Macior_foragers_by_plant_species_and_pollen_type.csv **Description:** 
 ##### Variables * Bee: bumble bee species * Plant: alpine plant species *
 Pollen Type: whether the pollen from the bees' corbiculae was
 "proper" (all from plant the bee was observed foraging on),
 "mixed+proper" (some 100x microscope views with proper pollen,
 some views with both proper and foreign pollen), "mixed" (all
 100x microscope views with both proper and foreign pollen), and
 "foreign" (only pollen from plants other than the plant the bee
 was observed foraging on) * N Individuals: number of bumble bee
 individuals observed on a given plant species with a given classification
 of corbicular pollen load #### File:
 Indl_bee_data_from_1-NMS_CO_bumble_bee_data_4.13.15_gdoc_-_all_alp_corb_counted_-_updated.csv **Description:** Data for bees observed in the modern network, with body measurements and corbicular pollen counts associated with some of the collected bees. Empty cells are equivalent to NA (data not collected). ##### Variables * YEAR: year of the observation * CLCTN.NO: number assigned to the bee at collection (some have errors denoted with "?") * ColctnNO.continuous: number assigned to the bee at collection (some numbers listed under "CLCTN.NO" were updated to be formatted like the majority of the bees) * BB.SPECIES: bumble bee species * CASTE: bumble bee caste (queen, worker, male) * DATE: date of collection * JD: Day of the year (number of days from the start of the year) * SITE: collection site (Niwot Ridge, Pennsylvania Mountain, or Mt. Evans) * ELVN: elevation * HABITAT: habitat type * TIME: time of collection * PLANT: plant species the bumble bee was collected on * CORBICULA?: presence of corbicular pollen load(s) * CORB.V.PHOTOS?: presence of photos of corbiculae * THORAX.WIDTH: width of the bee's thorax (mm) * WING.LENGTH: length of the bee's wing (mm)  * MASS.BODY: mass of the bee's body (mg) * BODY.LENGTH(HEAD2TAIL): length of the bee's body (mm) * INTERTEG.SPACE: intertegular distance (mm) * TL.LAB_PREM.GLOSSA.MaciorMethod: tongue length as measured using Macior's methods (mm) * TL.woPREMENTUM: tongue length without prementum included (mm) * Notes_body.measurements: Notes on the condition of the bee (e.g., missing wing) * BEE.NOTES: notes on bee species and caste identification * PLANT NOTES: notes on plant identification * Notes_pollen.counts: notes on pollen counts * FORAGER.TYPE.PROPER.1: whether the bee was a nectar forager  * FORAGER.TYPE.95: whether the bee was a nectar forager  * FORAGER.TYPE.75: whether the bee was a nectar forager  * N.CORB.VIEWS.CHECK: 1 if a corbicula was checked, otherwise NA * PRPN.CORB.VIEWS.CHECK: 1 if a corbicula was checked, otherwise NA * Corb.Prpn.V.Focal: proportion of microscope views with only focal pollen * Corb.Prpn.V.Mix: proportion of microscope views with mixed pollen * Corb.Prpn.F.For: proportion of microscope views with only foreign pollen * Corb.N.Views.WO.Pollen: number of microscope views without pollen * Corb.N.V.W.Pollen: number of microscope views with pollen * Corb.N.V.Focal: number of microscope views with only focal pollen * Corb.N.V.Mix: number of microscope views with mixed pollen * Corb.N.V.Foreign: number of microscope views with only foreign pollen * Corb.N.Types.Foreign: number of types of foreign pollen observed * No.Views.W.Pine: number of views with pine pollen * Body.N.PollenGrains.Focal: number of focal pollen grains collected from the bee body * Body.N.PollenGrains.Foreign: number of foreign pollen grains collected from the bee body #### File: Flower_tube_depth_mean_and_standard_deviation.csv **Description:**  ##### Variables * PLANT.SPECIES: plant species * MEAN: mean corolla length/tube depth (NA if data not available) * STANDARD.DEVIATION: standard deviation of corolla length/tube depth (NA if data not available) * N: number of measured individuals (NA if data was not available or if data was derived from a source that did not share the number of individuals measured) * PAST.ALP.MODULE: module assignment for the 1960s network (empty if not present in this network) * PRES.ALP.MODULE: module assignment for the 2010s network (empty if not present in this network) * PLANT.SHORT: shortened name for the plant species * 10.PLUS.PAST: whether the plant was observed at least 10 times in the historical network * 10.PLUS.PRES: whether the plant was observed at least 10 times in the modern network ## Code/software All analyses were completed in R. Data is provided in spreadsheets that can be viewed with Excel or another spreadsheet viewer. ## Access information Data for the 1960s network, for bumble bee tongue lengths, and for some flower measurements were derived from the following source: * Macior, L. W. (1974). Pollination ecology of the front range of the Colorado Rocky Mountains. *Melanderia*.