DOI: 10.5061/dryad.dz08kprzn
title: Data from: Pollen specialization is associated with later phenology in Osmia mason bees (Hymenoptera: Megachilidae)

description: 1. Species exhibit a range of specialisation in diet and other niche axes,
 with specialists typically thought to be more efficient in resource use
 but more vulnerable to extinction than generalists. Among herbivorous
 insects, dietary specialists seem more likely to lack acceptable host
 plants during the insect’s feeding stage, owing to fluctuations in
 host-plant abundance or phenology. Like other herbivores, bee species vary
 in host breadth from pollen specialisation (oligolecty) to generalisation
 (polylecty). 2. Several studies have shown greater interannual variation
 in flowering phenology for earlier-flowering plants than later-flowering
 plants, suggesting that early-season bees may experience substantial
 year-to-year variation in the floral taxa available to them. 3. We
 therefore reasoned that, among bees, early phenology could be a more
 viable strategy for generalists, which can use resources from multiple
 floral taxa, than for specialists. Consequently, we expected median dates
 of collection of adult specimens to be earlier for generalist species than
 for specialists. To test this, we obtained phenology data and pollen diet
 information on 67 North American species of the bee genus Osmia. 4.
 Controlling for latitude and phylogeny, we find that dietary
 generalisation is associated with significantly earlier phenology, with
 generalists active, on average, 11–14 days earlier than specialists. 5.
 This result is consistent with the generalist strategy being more viable
 than the specialist strategy for species active in early spring,
 suggesting that dietary specialisation may constrain the evolution of bee
 phenology—or vice versa.
description: <strong>lectydata.csv</strong>: Contains data on lecty and host-plant family for oligoleges for each of the 67 <em>Osmia</em> species used in our analysis. Lecty was determined from an exhaustive search of the literature combined with solicitation of expert opinion, Krombein's Catalog of Hymenoptera in America North of Mexico, and Fowler and Fowler & Droege's online databases of North American specialist bees. All lecty searching was done blind to phenology data. Classifications we deemed to be based on biased evidence (i.e., surveys of visitors to single plant taxa) were excluded. To stay consistent with the classifications used in most of the literature, monolectic species were classified as oligoleges, and eclectic oligoleges and mesoleges were classified as polylectic. <strong>occurrencedata.txt</strong>: Contains the dataset of <em>Osmia</em> bee occurrences that we used in our analyses, post cleaning (34 098 occurrences, one row per occurrence). Reference for original (pre-cleaning) dataset: GBIF. GBIF Occurrence Download [Internet]. 2021 [cited 2021 Feb 19]. Available from: https://doi.org/10.15468/dl.z2rupk. We downloaded the raw data from GBIF, including dates of capture, coordinates, and species names, for all <em>Osmia</em> bees between the latitudes of 45°N and 35°N and between the longitudes of 125°W and 60°W (70 126 total occurrences). <strong>R_code.pdf</strong>: all R code used to conduct our analyses. This pdf was made by knitting to html with Rmarkdown in R version 4.2.1.
description: Only R and the lectydata.csv and occurrencedata.txt files are
 needed to repeat all of our analyses using the code in R_code.pdf.
 Descriptions of all columns in the csv and txt files are all in the
 README.md document.