Abstract Detail

Ecology

Streher, Nathália Susin [1], Bergamo, Pedro Joaquim [2], Ashman, Tia-Lynn [3], Wolowski, Marina [4], Sazima, Marlies [5].

Trait and density drivers of heterospecific pollen deposition in a biodiverse tropical highland community.

In diverse co-flowering communities, plant species can interact indirectly by altering pollinator foraging decisions and consequently pollinator visitation. Pollinator movement among different plant species can result in heterospecific pollen deposition on stigmas which can affect plant reproduction. Similar to pollinator visitation, heterospecific pollen deposition is hypothesized to be trait- and density-mediated. Assessing the drivers of heterospecific pollen receipt in natural conditions can reveal the consequences of pollinator sharing on community assembly. Here, we investigated which species-specific and community-related reproductive traits (floral tube length, flower size, stigma height, stigma exposure, pollination system, floral abundance, distinctiveness between species stigma and community anthers, floral color distinctiveness, and flowering synchrony) mediate the intensity of species heterospecific pollen receipt in a biodiverse tropical highland community. We also tested whether the proportion of heterospecific pollen receipt of individuals within species is affected by neighbor flower density. We systematically sampled 978 stigmas from 30 species over two flowering seasons: we enumerate pollen grains received and related them to the surrounding community floral traits and co-flowering densities. All species analyzed received heterospecific pollen grains but the loads varied extensively among individuals. Our results indicated that species with stigmas more extended beyond corolla captured more heterospecific pollen. Species that were visited by only one pollinator functional group (functionally specialist flowers) received more heterospecific pollen load than generalist ones (functionally generalist flowers). This unexpected tendency may be a sign of the pollinators' generalization that visit the specialized plants. The heterospecific pollen proportion (in relation to total load) that individuals received depended on the interaction between conspecific and heterospecific densities and was scale-dependent. At neighbor scale (within a 2m radius), high numbers of conspecifics and heterospecifics diminished the proportion of heterospecific pollen receipt. Conversely, at landscape scale (0.2ha of the total area sampled), the same co-flowering pattern enhanced the proportion of heterospecific pollen receipt. Interestingly, flowering with heterospecifics seems to be a good pollination strategy if it occurs in small patches where everyone’s flowering densities are high. The larger flowering display that emerges may maintain floral constancy of pollinators or a floral complex arrangement that avoids heterospecific pollen among nearby neighbors. Therefore, our study suggests that processes regulating heterospecific pollen receipt may differ in tropical highland communities.

1 - University of Campinas, Campinas, SP, Brazil
2 - Rio de Janeiro Botanical Garden, Rio de Janeiro, Rio de Janeiro, RJ, Brazil
3 - Department Of Biological Sciences, 4249 Fifth Avenue & Ruskin, Pittsburgh, PA, 15260, United States
4 - Federal University of Alfenas, Institute of Natural Sciences, Alfenas, MG, Brazil
5 - University of Campinas, Plant Biology Department, Campinas, SP, Brazil

Keywords:
plant-pollinator interactions
pollen deposition
plant reproduction
pollination
Tropical plants.

Presentation Type: Oral Paper
Session: ECO8, Ecology: Interactions
Location: /
Date: Friday, July 23rd, 2021
Time: 10:45 AM(EDT)
Number: ECO8004
Abstract ID:564
Candidate for Awards:None