Pollination success increases with plant diversity in high-Andean communities

Sabrina S Gavini,Cristina Tur,Agustín Sáez,Marcelo A Aizen

doi:10.1038/s41598-021-01611-w

Abstract

Pollinator-mediated plant–plant interactions have traditionally been viewed within the competition paradigm. However, facilitation via pollinator sharing might be the rule rather than the exception in harsh environments. Moreover, plant diversity could be playing a key role in fostering pollinator-mediated facilitation. Yet, the facilitative effect of plant diversity on pollination remains poorly understood, especially under natural conditions. By examining a total of 9371 stigmas of 88 species from nine high-Andean communities in NW Patagonia, we explored the prevalent sign of the relation between conspecific pollen receipt and heterospecific pollen diversity, and assessed whether the incidence of different outcomes varies with altitude and whether pollen receipt relates to plant diversity. Conspecific pollen receipt increased with heterospecific pollen diversity on stigmas. In all communities, species showed either positive or neutral but never negative relations between the number of heterospecific pollen donor species and conspecific pollen receipt. The incidence of species showing positive relations increased with altitude. Finally, stigmas collected from communities with more co-flowering species had richer heterospecific pollen loads and higher abundance of conspecific pollen grains. Our findings suggest that plant diversity enhances pollination success in high-Andean plant communities. This study emphasizes the importance of plant diversity in fostering indirect plant–plant facilitative interactions in alpine environments, which could promote species coexistence and biodiversity maintenance.

Highlights

Pollinator-mediated plant–plant interactions have traditionally been viewed within the competition paradigm
Tur et al.[7] showed that for many species increases in heterospecific pollen receipt were accompanied by increases in conspecific pollen deposition and germination on stigmas, and proposed that the relation between conspecific and heterospecific deposition on stigmas can be used as a proxy for the plant cost–benefit balance derived from pollinator sharing
We counted a total of 166,945 pollen grains (159,373 conspecific pollen (CP) and 7572 heterospecific pollen (HP) grains) on 9371 stigmas across the nine communities (Fig. S1), representing 88 high-Andean species from 27 angiosperm families (Table S1)

Summary

Introduction

Pollinator-mediated plant–plant interactions have traditionally been viewed within the competition paradigm. Species showed either positive or neutral but never negative relations between the number of heterospecific pollen donor species and conspecific pollen receipt. The study of interspecific pollen transfer can be useful to better understand the role of pollinator-mediated plant–plant interactions as drivers of plant species coexistence and diversity. Heterospecific pollen grains can come from a single or multiple donor s pecies[7,20,23] This substantial variation within and among species in both the magnitude and diversity of heterospecific pollen loads may be due to several factors such as differences in plant specialization, flower symmetry and size, flower lifespan, floral display, and associated pollinator group[12,22,24]. The species diversity and composition of the stigmatic pollen community provide information on patterns of pollinator movement among co-occurring flowering plant species, and on the functional consequences of pollinator s haring[7,14]

Methods

Results

Discussion

Conclusion