DOI: 10.5061/dryad.m72m9
title: Data from: High-elevation range limit of an annual herb is neither caused nor reinforced by declining pollinator service

description: 1. Pollination failure has been proposed to be an important determinant of
 plant species’ range limits, if pollinator activity declines along an
 environmental gradient, directly limiting plant populations, or if plant
 populations decline along an environmental gradient and subsequently fail
 to attract sufficient visitation. Both mechanisms predict reduced
 pollinator visitation, increased pollen limitation, and decreased seed
 production towards range limits, and the first additionally predicts
 declining pollinator abundance independent of any particular plant
 species. However, many self-compatible species have some capacity for
 autonomous self-fertilization, which may buffer reproductive success from
 declining pollinator visitation if inbreeding depression is mild. Thus
 pollinator-mediated limits may also predict selection for reduced reliance
 on pollinators towards range limits. 2. We tested these predictions
 towards the high-elevation limit of the self-compatible, bumble bee
 (Bombus) pollinated Rhinanthus minor, along two elevation transects in the
 Rocky Mountains of Alberta, Canada. 3. Bombus abundance was highest at
 mid- (range-centre) and high-elevation (range limit) sites, so declining
 pollinator abundance is unlikely to impose high-elevation limits for
 bumble bee pollinated species in this area. 4. Flowers per plant and per
 m2 declined at upper range limits, potentially rendering edge populations
 less attractive. However, visitation rate did not decline towards the
 range limit at either transect. Stigmatic pollen receipt declined with
 increasing elevation, but seed set did not, nor did outcross pollen
 supplementation increase seed set at any site. 5. Investment in floral
 attractiveness (corolla area/ovary area) increased towards range limits,
 but capacity for high-quality autonomous seed set and adult inbreeding
 coefficients inferred from genetic markers were uniformly high, suggesting
 frequent self-fertilization and weak inbreeding depression throughout the
 range. 6. Synthesis We found no evidence for pollination failure towards
 the upper range limit of R. minor. Moreover, unlike some species with a
 capacity for autogamy, autonomous selfing makes a major contribution to R.
 minor's mating system and demography, and likely buffers reproductive
 success from stochasticity in pollination. Continued investment in floral
 attractiveness despite high autonomous selfing suggests some evolutionary
 benefit to pollinator-mediated outcrossing, rather than ecological
 benefits via increasing seed quantity or quality. Given that &gt;50%
 of angiosperms are self-compatible, the reproductive assurance provided by
 selfing may reduce the importance of pollination in limiting plant
 distributions compared to other biotic interactions.
description: Data from Hargreaves
 etal (2015) JEcol Pollination of Rhinanthus minorAll data used in
 analyses are included in this file. Sheets are: 1) Bombus specimen
 identifications collected during pan-trapping, 2) compiled data from
 pollinator observations on Rhinanthus minor, 3) seed counts from
 experimental plants, 4) counts of pollen grains on R. minor stigmas, 5)
 demographic data from randomly-selected plants surveyed at the end of
 flowering. Final sheet includes meta data explaining column
 headings.Hargreaves etal (2015) JEcol
 data Dryad.xlsx