Pollen limitation, species’ floral traits and pollinator visitation: different relationships in contrasting communities

Abstract

Failures in the process of pollen transfer among conspecific plants can severely impact female reproductive success. Thus, pollen limitation can cause selection on plant mating systems and floral traits. The relationships between pollen limitation and floral traits might be partly mediated by the quantity and identity of pollinator visits. However, very little is known about the relationship between pollinator visits and pollen limitation. We examined the relationships between pollen limitation and floral traits at the community level to connect them to community ecology processes. We used 48 plant species from two contrasting communities: one species‐rich lowland community and one species‐poor alpine community. In addition, we calculated visitation rates and ecological pollination generalization for 38 of the species to examine the relationship between pollinator visitation and pollen limitation at the community level. We found low overall levels of pollen limitation that did not differ significantly between the alpine and the lowland community. In both communities, species with evolutionary specialized flowers were more pollen limited than species with unspecialized flowers. Species’ visitation rates and selfing capability were negatively related to pollen limitation in the alpine community, where pollinators are scarcer. However, flower size/number, ecological generalization of plants and flowering onset had greater effects on pollen limitation levels at the lowland community, indicating that the identity of the visitors and plant‐plant competitive interactions are more decisive for plant reproduction in this species‐rich community. There, pollen limitation increased with flower size and flowering onset, and decreased with ecological generalization, but only in species with evolutionary specialized flowers. Our study suggests that selection on plant mating system and floral traits may be idiosyncratic to each particular community and highlights the benefits of conducting community‐level studies for a better understanding of the processes underlying evolutionary responses to pollen limitation.

Competition for pollinators and intra‐communal spectral dissimilarity of flowers

“…; Lázaro et al . ). Future studies on plant–pollinator interactions will help explain the differences in plant reproductive strategies between populations.…”

Pattern of flower size variation along an altitudinal gradient differs between Impatiens textori and Impatiens noli-tangere

“…Pollen limitation can cause selection on various floral traits (e.g. flowering duration, flower size, and number of flowers) (Ashman et al 2004;Parachnowitsch & Kessler 2010;Lázaro et al 2015). Therefore, floral traits other than flower size may also differ between lower and higher altitude populations in I. textori.…”

Plastic Responses Contribute to Explaining Altitudinal and Temporal Variation in Potential Flower Longevity in High Andean Rhodolirion montanum

“…A broad meta-analysis found no difference in pollen-limitation levels for alpine and lowland species ([24], see also [25]); Wagner et al [26] recently established that nival flowers in the Tyrolean Central Alps are not pollinator-visitor limited. This could be because alpine species possess compensatory traits that allow them to deal with pollinator scarcity thereby decreasing pollen limitation [27–30].…”