Publisher Correction: GloPL, a global data base on pollen limitation of plant reproduction.

J. H. Burns was omitted in error from the author list of the original version of this Data Descriptor. This omission has now been corrected in both the HTML and PDF versions.

GloPL, a global data base on pollen limitation of plant reproduction.

Plant reproduction relies on transfer of pollen from anthers to stigmas, and the majority of flowering plants depend on biotic or abiotic agents for this transfer. A key metric for characterizing if pollen receipt is insufficient for reproduction is pollen limitation, which is assessed by pollen supplementation experiments. In a pollen supplementation experiment, fruit or seed production by flowers exposed to natural pollination is compared to that following hand pollination either by pollen supplementation (i.e. manual outcross pollen addition without bagging) or manual outcrossing of bagged flowers, which excludes natural pollination. The GloPL database brings together data from 2969 unique pollen supplementation experiments reported in 927 publications published from 1981 to 2015, allowing assessment of the strength and variability of pollen limitation in 1265 wild plant species across all biomes and geographic regions globally. The GloPL database will be updated and curated with the aim of enabling the continued study of pollen limitation in natural ecosystems and highlighting significant gaps in our understanding of pollen limitation.

Selection on intra-individual variation in stigma-anther distance in the tropical tree Ipomoea wolcottiana (Convolvulaceae).

It is well known that animals can exert strong selective pressures on plant traits. However, studies on the evolutionary consequences of plant-animal interactions have mainly focused on understanding how these interactions shape trait means, while overlooking its potential direct effect on the variability among structures within a plant (e.g. flowers and fruits). The degree of within-plant variability can have strong fitness effects but few studies have evaluated its role as a potential target of selection. Here we reanalysed data on Ipomoea wolcottiana stigma-anther distance to test alternate mechanisms driving selection on the mean as well as on intra-individual variance in 2 years. We found strong negative selection acting on intra-individual variation but not on mean stigma-anther distance, suggesting independent direct selection on the latter. Our result suggests that intra-individual variance has the potential to be an important target of selection in nature, and that ignoring it could lead to the wrong characterisation of the selection regime. We highlight the need for future studies to consider patterns of selection on the mean as well as on intra-individual variance if we want to understand the full extent of plant-animal interactions as an evolutionary force in nature.

Patterns and sources of variation in pollen deposition and pollen tube formation in flowers of the endemic monoecious shrub Cnidoscolus souzae (Euphorbiaceae).

Pollen deposition and pollen tube formation are key components of angiosperm reproduction but intraspecific variation in these has rarely been quantified. Documenting and partitioning (populations, plants and flowers) natural variation in these two aspects of plant reproduction can help uncover spatial mosaics of reproductive success and underlying causes. In this study, we assess variation in pollen deposition and pollen tube formation for the endemic monoecious shrub Cnidoscolus souzae throughout its distribution range in Mexico, and determine how this variation is structured among populations, plants and flowers. We also infer the relative importance of pollen quantity and quality in determining pollination success in this species. While we found no evidence suggesting that pollen receipt limits C. souzae reproduction across 19 populations, we did find extensive variation in pollen load size and pollen tube number per flower. Total variation in pollen receipt and pollen tube number was mostly explained by intra-individual and among-population variance. Furthermore, pollen load size had a stronger effect on the number of pollen tubes at the base of the style than pollen germination rate, suggesting that pollen quantity may be more important than quality for pollen tube success in C. souzae. Our results suggest that both small within-plant flower differences and broad-scale differences in community attributes can play an important role in determining pollination success. We emphasise the need to evaluate patterns and sources of variation in pollen deposition and pollen tube formation as a first step in understanding the causes of variation in pollination success over broad spatial scales.

Anther and stigma morphology in mirror-image flowers of Chamaecrista chamaecristoides (Fabaceae): implications for buzz pollination.

Enantiostyly (mirror-image flowers) is usually associated with buzz pollination. In buzz-pollinated flowers, pollen is released through terminal pores after bees vibrate the stamens. Several studies have evaluated the function of 'buzzing' in pollen release, but less attention has been paid to the effect of buzzing on pollen capture and deposition on stigmas. Evaluating the mechanism of pollen dispersion in buzz-pollinated flowers is important because it may affect mating patterns and reproductive success. In this study, we analysed the morphology of sexual organs (anther and stigma) using electron microscopy, and determined the relationship between sexual organ structure and pollen capture function through experimental manipulations of buzz-pollinated flowers of Chamaecrista chamaecristoides, as well as vibration frequencies on floral visitors. Pollen release occurs through two terminal pores at the tip of the stamens. However, unlike most angiosperms that have their stigmatic surface exposed, C. chamaecristoides presents a stigmatic surface inside a cavity covered by trichomes. Experimental manipulations showed that effective fertilisation is only achieved when the style is vibrated, suggesting that buzzing is not only important for pollen release but also for pollen capture and deposition on the stigma. This result, in addition to vibration frequency analysis, suggests that although all floral visitors buzz flowers only those that buzz at higher frequencies achieve effective fertilisation. The anatomical features of sexual organs in flowers of C. chamaecristoides demonstrate that this species possesses a highly specialised, elaborate morphology, with both genders selected for traits that promote buzz pollination.