DOI: 10.5061/dryad.cc2fqz6g9
title: Data from: Fitness costs and benefits of a non-native floral resource for subalpine solitary bees

description: Organisms inhabiting seasonal environments must fit their life cycle into
 a limited time window while also synchronizing periods of resource
 consumption with timing of resource availability. Introduced non-native
 species, which often differ in phenology from natives, can alter and
 expand the seasonal window of resource availability for native consumers,
 providing potential fitness benefits. However, if these non-native
 resources are nutritionally unsuitable for native consumers, their
 presence could elicit foraging behaviour that proves maladaptive—i.e.,
 they could act as an ecological trap. Here, we used multi-year field
 observations and a laboratory experiment to investigate the impacts of a
 common non-native plant species on two components of fitness in three
 solitary bee species (all specialist consumers of pollen from the plant
 family Asteraceae) native to the Colorado Rocky Mountains. First, we
 tested whether individual bees that collect pollen from the non-native
 common dandelion (Taraxacum officinale) produce more offspring than those
 that do not, thanks to the unusually early flowering phenology of the
 non-native. Second, we compared survival of bee larvae experimentally
 reared on Taraxacum pollen to that of larvae reared on native Asteraceae
 pollen. Bees that used at least some non-native Taraxacum pollen produced
 more potentially viable offspring, but larval survival was significantly
 reduced for bee larvae experimentally fed provisions dominated by
 Taraxacum pollen. Therefore, survival costs may negate the potential
 fitness benefits of early nesting, indicating that non-native floral
 resource use may act as an ecological trap for native bees. Using a series
 of simple simulations informed by our results, we explore the fitness
 effects of non-native floral resource use, demonstrating that the net cost
 or benefit depends on how bees respond to resource shortages. Our results
 highlight the importance of considering organisms’ full life cycles when
 evaluating the fitness consequences of resource availability and species
 introductions.
description: # Data from: Fitness costs and benefits of a non-native floral resource
 for subalpine solitary bees
 [https://doi.org/10.5061/dryad.cc2fqz6g9](https://doi.org/10.5061/dryad.cc2fqz6g9) ## Description of the data and file structure Data were collected to test the extent to which three *Osmia* bee species use pollen from a non-native plant species, *Taraxacum officinale* (common dandelion), and the fitness consequences of their using that pollen. Data were also collected on flowering phenology of native and non-native plants at the study sites, and overwinter survival of bees developing from eggs laid at different times during the summer. ### Files and variables #### File: Osmia\_2017\_survival\_to\_emergence.txt **Description:** Data from 2017 on nest initiation and the number of eggs laid by individual bees that survived to emergence in 2019. These data are represented in Fig. 1B of the manuscript. ##### Variables * Taxon: Bee genus and species observed. * Subgenus: Subgenus to which bee species belongs. * Site: Two-letter code identifying study site where bee was observed. * Mother's individual code: Individual code made up of study site, taxon, and colour marking on bee. * Nest ID: Nest identifier consisting of 2-letter site code + nest block identifier (normally A-L) + hole number (1-10). A suffix letter "b" indicates a second nest constructed in the same hole. * DOY first egg laid: Day since Jan. 1 of that year that the individual's first egg in that nest was laid. * Total cells in nest: Total number of cells within that nest. * Cells with host fate known: Number of cells in each nest in which the survival status of the host could be measured. * Count of hosts eaten: Number of cells in each nest in which the host was parisitized, predated, or chewed through by an emerging parasite. * Count of hosts survived: Number of cells in which the host survived. * Prop hosts survived: Number of hosts that survived in each nest divided by the number of hosts in that nest for which fate is known. * Prop non-eaten hosts survived: Number of hosts that survived in each nest divided by the number of hosts in that nest for which fate is known and were not eaten. * DOY last egg laid: Day since Jan. 1 of that year that the individual's last egg in that nest was laid. #### File: floral\_abd\_data\_2013-2019.txt **Description:** Floral densities recorded for selected plant taxa at each study site between 2013 and 2019. See [https://portal.edirepository.org/nis/metadataviewer?packageid=edi.890.4](https://portal.edirepository.org/nis/metadataviewer?packageid=edi.890.4) for detailed metadata. These data are represented in Fig. 1A of the manuscript. ##### Variables * Year: Year in which floral abundance was measured. * Site: Two- or three-letter code identifying study site where floral abundance was measured. * Date: Date on which floral abundance was measured. * Day of year: Day since Jan 1. of that year the sampling date corresponds to. * Sampling occasion: Corresponds to the number of visits made in that year to that site, numbered from 1 (first sampling occasion of the year at a site) to 23. * Plant taxon: Genus and species name. * Higher taxon: Genus, tribe, or family to which plant taxon belongs. * Family: Family to which plant taxon belongs. * Floral units counted: Flowers whenever possible, capitula when florets were too densely packed (i.e. Asteraceae species). * Distance to first 100 units m: Distance in metres from centre of site to 100th flower. Flowers were counted by starting at the marked centre of the site and counting each flower/capitula encountered while walking in a spiral shape outwards. * Notes: Notes recorded in the field. * Area surveyed m2: Circular area surveyed in metres squared. Calculated using distance to first 100 units as radius. * Density no per m2: Floral density in numbers per square m. Calculated by dividing flowers counted (normally 100) by area surveyed. * Flowers counted by: Initials or name of person or people who counted this taxon on this sampling occasion. * Data entered by: Initials of person who entered data. * Verified by: Initials of person who verified data entry. * Verification notes: Notes recorded during data verification. #### File: RP\_nest-height\_experiment\_2013-2016.txt **Description:** Data on fates of individual bee eggs laid in nests constructed in experimental trapnests at Rosy Point (RP) site between 2013 and 2015. Trapnests were deployed at two different heights, and completed nests experimentally allocated to different heights, to test impacts of overwinter snow cover on survival. However, the nest height variable was not of interest for the present study. These data are represented in Fig. 1C of the manuscript. ##### Variables * Year: Year in which data were collected. * Host taxon: Genus and species of bee that built the nest. * Bee subgenus: Subgenus to which host bee species belongs. * Bee species: Specific epithet of the host bee. * Mother colour: Unique colour marking applied to the mesosoma of the bee who built the nest. * Nest ID: Nest identifier consisting of 2-letter site code + nest block pair identifier (A-L) + nest height identifier (L or H; see below) + hole number (1-10). A suffix letter "b" indicates a second nest constructed in the same hole. Nest blocks were deployed in pairs attached to high or low positions on the same tree. * Cell number: Brood cell number within nest. Numbered consecutively, starting with the innermost = 1. * Est date laid: Estimated date the egg within that brood cell was laid. Interpolated if egg was laid between sampling days. * Est doy laid: Day since Jan. 1 of that year corresponding to the estimated date the egg was laid. * Nest constructed after departure: "y" if entire nest was constructed after the departure of the field crew from the field station in mid-August 2015, such that estimated dates are highly uncertain. * Initial nest height: "L" = bee constructed nest in block attached to tree at ~0.5 m above ground level (below winter snowpack); "H" = bee constructed nest in block attached to tree at ~1.5 m above ground level (above winter snowpack) * Overwinter nest height: Low or high, as for initial nest height. This is the position at which each nest spent its first winter (assigned by researcher in preceding August). * Nest location first winter: Specific location at which nest spent its first winter. "X" prefix indicates blocks set up solely for housing overwintering nests. * Status start 2nd summer: Indicates whether host bee was alive, dead, or eaten at the start of the summer (May/June) following the year of nest construction. eaten = host bee consumed by parasite or predator; dead = host bee died for reasons other than parasitism/predation. * Alive.dead.2nd.summer: Binary: 0 if host bee dead or eaten, 1 if alive at start of 2nd summer. * Stage start 2nd summer: Developmental stage of host bee at start of 2nd summer:  * E = egg * FL = feeding larva (i.e. had not yet begun defecating) * DL = defecating larva * SL = spinning larva (i.e. larva had begun but not completed cocoon-spinning) * LC = larva in cocoon (=prepupa) * PC = pupa in cocoon * Parasite.predator ID: If host bee eaten, identity of the parasite/predator responsible. * Notes: Field notes. #### File: Taraxacum\_egg-transfer\_expt\_2018-2019.txt **Description:** Data from the bee egg-transfer experiment conducted in 2018 and 2019. These data are represented in Fig. 4 of the manuscript. ##### Variables * Year: Year transfer took place. * Block: Identity of wooden block to which egg was transferred in laboratory.  * Well: Well number within block egg was transferred to. * Pollen source nest: Nest identifier consisting of 2-letter site code + nest block identifier (normally A-L) + hole number (1-10). A suffix letter "b" indicates a second nest constructed in the same hole. * Pollen source cell: Brood cell number within nest that pollen originated from. Numbered consecutively, starting with the innermost = 1. * Pollen source species: Bee genus and species or subgenus that built the nest from which the pollen provision was taken. * Pollen type: Pollen identified as *Taraxacum* (= Cichoriae) or other Asteraceae if more than 80 of first 100 grains randomly counted on slide were of each respective pollen type. * Bee source: ID of nest that transferred egg originated in, consisting of 2-letter site code, nest letter (A-L) and hole number within nest (1-10). * Bee source cell: Cell number within nest that transferred egg originated in. * Est date laid: Estimated date transferred egg was originally laid, interpolated between site visits. * Mean date laid: Mean date transferred egg was originally laid if estimated date laid is a range. * Est DOY laid: Day since Jan 1. of that year corresponding to mean date laid. * Bee species: Bee genus and species to which egg belongs. * Bee subgenus: Subgenus to which egg belongs, either *Helicosmia* or *Cephalosmia*. * Origin pollen: Pollen type transferred egg originated on. Pollen was identified as '*Taraxacum*' or 'other Asteraceae' if more than 80 of first 100 grains randomly counted on slide were of each respective pollen type. * Transferred as: Whether bee was transferred at egg stage (E) or larval stage (L). Most were transferred as young larvae, due to higher fragility of eggs. No larvae estimated to be older than 7 days (17 days from estimated date egg laid) were transferred. * Transfer date: Date on which egg or larva was transferred. * Est age at transfer: Difference between date of transfer and mean date laid (measured in days). * Est eclosion date: Date on which transferred egg or larva was estimated to have eclosed (hatched). * Day of event yr 1: Date on which bee died or completed a cocoon, or date experiment ended if larva was still alive when we left research station. * Event: Bee status or developmental stage on day of event: * dead * cocoon (larva presumed alive, with completed cocoon) * alive (larva alive but cocoon not yet fully formed). * Days to event: Days between transfer and event. * Survival: Binomial: 1 for death and 0 for cocoon or alive. #### File: Taraxacum\_use\_2013-2019\_with\_fitness\_data.txt **Description:** Data on pollen usage and numbers of offspring produced by 189 individual bees of three Asteraceae-specialist species. These data are represented in Figs. 2, 3, and A6 of the manuscript. ##### Variables * Year: Year in which bee nest was built. * Species: Bee genus and species * Site_code: Two- or three-letter code identifying study site where bee was observed. * Bee_id: Unique colour marking applied to bee individual's mesosoma. * Individual: Unique individual ID consisting of bee species, site code, colour marking, and year of observation. * Min_date_of_first_cell: Date on which first cell was laid. Earliest date was taken (Min) rather than the later date (Max) if estimated date laid was a range. * Taraxacum_Y.N: Whether Taraxacum was found in the nest. Binomial variable Yes(Y)/No(N). * Day_of_year first cell: Day since Jan. 1 of that year corresponding to min date. * Sum_of_count_Taraxacum: Total number of Taraxacum pollen grains counted in nests built by this bee individual. * Sum_of_count_Asteraceae: Total number of Asteraceae pollen grains counted in nests built by this bee individual. * Sum_of_count_other: Total number of pollen grains that are not Taraxacum or Asteraceae counted in nests built by this bee individual. * Offspring_produced_Jul_22: Total fully completed brood cells created up to Jul 22. * Offspring_unrounded_Jul_22: Total fully completed and partially completed brood cells created up to Jul 22. * Offspring_produced_Jul_27: Total fully completed brood cells created up to Jul 27. * Offspring_unrounded_Jul_27: Total fully completed and partially completed brood cells created up to Jul 27. * Offspring_produced_Aug_1: Total fully completed brood cells created up to_Aug_1. * Offspring_unrounded_Aug_1: Total fully completed and partially completed brood cells created up to Aug 1. * Offspring_produced_Aug_6: Total fully completed brood cells created up to Aug 6. * Offspring_unrounded_Aug_6: Total fully completed and partially completed brood cells created up to Aug 6. * Offspring_produced_Aug_11: Total fully completed brood cells created up to Aug 11. * Offspring_unrounded_Aug_11: Total fully completed and partially completed brood cells created up to Aug 11. * Total_offspring: Total brood cells created throughout the nesting season. * Slide_transects_scored: Number of transects scored for pollen on microscope slide. There were four random transects selected and scored for each brood cell sample. * Brood_cells_scored: Number of brood cells scored for this individual. * Pollen was sampled from the innermost and outermost brood cells of each nest, or just the innermost brood cell if total cells in the nest was less than 4. #### File: Taraxacum\_use\_2013-2019\_by\_brood\_cell.txt **Description:** Data on usage of *Taraxacum* versus other Asteraceae flowers at the level of individual brood cells. These data are represented in Fig. A5. ##### Variables * Year: Year in which nest was constructed. * Species: Bee genus and species. * Site_code: Two- or three-letter code identifying study site where bee was observed. * Bee_id: Unique colour marking applied to bee individual's mesosoma. * Individual: Unique individual ID consisting of bee species, site code, colour marking, and year of observation. * Nest_code: Nest identifier consisting of a one-letter nest block or block pair identifier (A-L) + one-letter nest height identifier (L or H) + hole number (1-10). * A suffix letter "b" indicates a second nest constructed in the same hole. * Cell_number: Brood cell number within nest that pollen originated from. Numbered consecutively, starting with the innermost = 1. * Min_date_of_cell_construction: Estimated date on which brood cell construction began. * Day_of_year: Day since Jan. 1 of that year corresponding to min date. * Sum_of_count_Taraxacum: Total number of Taraxacum pollen grains counted in nests built by this bee individual. * Sum_of_count_Asteraceae: Total number of Asteraceae pollen grains counted in nests built by this bee individual. * Sum_of_count_other: Total number of pollen grains that are not Taraxacum or Asteraceae counted in nests built by this bee individual. * Taraxacum_Y.N: Whether Taraxacum was found in the sample. Binomial variable Yes(Y)/No(N). Missing data: NA ## Code/software The script was written in R version 4.1.1. Copyright (C) 2021 The R Foundation for Statistical Computing. Platform: x86_64-w64-mingw32/x64 (64-bit) Packages lmerTest (Kuznetsova et al. 2017) and scales (Wickham & Seidel 2022) must be installed to calculate parameter values for the simulation. The script calculates expected lifetime reproductive output and number of surviving offspring for bees that begin nesting on any given day of the season, under different hypotheses about *Taraxacum* usage and its fitness costs. ## Access information Other publicly accessible locations of the data: * Floral data and site metadata are available at: [https://portal.edirepository.org/nis/metadataviewer?packageid=edi.890.4](https://portal.edirepository.org/nis/metadataviewer?packageid=edi.890.4) * Data on bee nesting rates (used in simulation) can be found here: [https://datadryad.org/stash/dataset/doi:10.5061/dryad.59zw3r26d](https://datadryad.org/stash/dataset/doi:10.5061/dryad.59zw3r26d) and processed using the scripts here: [https://zenodo.org/record/4553785#.Y1r5a3bMKUk](https://zenodo.org/record/4553785#.Y1r5a3bMKUk)