Do Tropical Bird‐Pollinated Plants Exhibit Density‐Dependent Interactions? Field Experiments

@article{Feinsinger1991DoTB,
  title={Do Tropical Bird‐Pollinated Plants Exhibit Density‐Dependent Interactions? Field Experiments},
  author={Peter Feinsinger and Harry M. Tiebout and Bruce E. Young},
  journal={Ecology},
  year={1991},
  volume={72},
  pages={1953-1963}
}
In a tropical cloud forest at Monteverde, Costa Rica, three understory shrub species overlap greatly in flowering seasons and share hummingbird pollinators (Lampornis calolaema). We conducted two field experiments to determine if a plant's pollination and subsequent reproductive output reflect local densities of conspecific and heterospecific flowers. We controlled floral composition in the neighborhoods surrounding 12 focal plants of self—compatible Besleria triflora (Gesneriaceae) and of self… 
Heliconia acuminata reproductive success is independent of local floral density
TLDR
It is argued the absence of neighborhood effects may be a general phenomenon in central Amazonian forests, though additional experiments with other plant-pollinator systems are needed to determine the extent to which this hypothesis is supported.
Population dependence in the interactions with neighbors for pollination: A field experiment with Taraxacum officinale.
TLDR
This study shows that a similar local neighborhood can differentially affect the frequency and foraging behavior of pollinators, even in closely situated populations.
Pollinator-mediated competition between two congeners, Limnanthes douglasii subsp. rosea and L. alba (Limnanthaceae).
TLDR
Under natural pollination conditions, heterospecific pollen transfer has the ability to decrease the fertility of L. rosea when it occurs at low frequency in mixed stands, and pollinator-mediated competition may contribute to the locally disjunct distributions of these two species.
Effects of Inbreeding, Outbreeding, and Supplemental Pollen on the Reproduction of a Hummingbird‐pollinated Clonal Amazonian Herb
TLDR
It is concluded that high rates of geitonogamy due to clonality and pollen limitation due to the short receptivity of flowers and patchy distribution constrain the reproduction of this clonal herb.
Pollination in a patchily distributed lousewort is facilitated by presence of a co-flowering plant due to enhancement of quantity and quality of pollinator visits.
TLDR
Differences in floral architecture induced differences in pollinator behaviour that minimized IPT, such that co-flowering plants significantly enhanced quantity and quality of pollinator visits for the lousewort plants in patchy habitat.
Consequences of plant population size and density for plant–pollinator interactions and plant performance
TLDR
It is concluded that plant–pollinator interactions are sensitive to changes in both the size and spatial arrangement of plant populations, which can affect their demography and genetics.
Sex and the single mustard : population density and pollinator behavior effects on seed-set
TLDR
The most dramatic density effects occurred where pollinators were induced to behave as generalists, suggesting that density—related declines in pollinator quality are more important than parallel declines in the quantity of visits.
Pollen limitation and effects of local patch density on reproductive success in the alpine herb Inula royleana (Asteraceae)
In alpine species depending on insects for pollination, the decrease of pollinator abundance and activity, due to more hostile weather and climatic conditions, could limit reproductive success
Forest Fragmentation, Pollination, and Plant Reproduction in a Chaco Dry Forest, Argentina
TLDR
Overall, levels of pollination and seed production undoubtedly integrated many idio- syncratic effects of fragmentation on particular plant and animal populations, and indicated that "community health" of fragments suffered in comparison with that of continuous forest.
...
...

References

SHOWING 1-10 OF 41 REFERENCES
Floral neighborhood and pollination success in four hummingbird-pollinated cloud forest plant species.
TLDR
The potential existed for floral neighborhoods to affect seed set and fitness of plants and competitive effects from neighboring heterospecific plants were only sporadic in the species the authors examined, and were particularly infrequent in those species with long flowers adapted for long-billed hummingbirds.
Competition for Hummingbird Pollination and Sequential Flowering in Two Colorado Wildflowers
TLDR
Fecundity reductions in natural and synthetic mixtures of D. nelsoni and I. aggregata indicate that the 2 species compete for hummingbird pollination and suggest that the competitive interaction involves interspecific pollen transfer.
DISTURBANCE, POLLINATOR PREDICTABILITY, AND POLLINATION SUCCESS AMONG COSTA RICAN CLOUD FOREST PLANTS'
TLDR
Interactions between plants and hummingbirds examined are insensitive to patch type, and habitat—related contrasts in plant reproductive traits and plant—pollinator interactions documented in other studies, which compare habitats initiated by anthropogenic disturbances with undisturbed patches, may be artifacts to some extent.
Evaluation of Character Displacement Among Plants in Two Tropical Pollination Guilds
TLDR
The absence of expected pattern indicates that competition never occurs or that competition is an inconsequential ecological event, but attribute absence of pattern to the following aspects of biological variability: the nature of interspecific interactions varies with changes in species composition, which occur over short distances, and Gleasonian ecologies that change distri- bution and abundance faster than natural selection or diffuse competition can screen out improper phenotypes.
Ecology and evolution of self-pollination in Arenaria uniflora (Caryophyllaceae)
TLDR
It is hypothesized that the stimulus for the evolution of self-pollination in A. uniflora was competition for pollinators, and within-site transplants performed better than between- site transplants, especially in dry years.
Disturbance and Predictability of Flowering Patterns in Bird-Pollinated Cloud Forest Plants.
TLDR
Predictability of flower and nectar production tended to be greatest in treefalls, which are foci of concentrated flowering activity by all species, and Phenotypic specialization by plants for co-evolved interactions with hummingbirds will be lowest in large gaps, highest in forest, and intermediate in tree falls.
Competition among plants sharing hummingbird pollinators : laboratory experiments on a mechanism
TLDR
The collective results demonstrate that studying the role of particular interactions in community structure must involve examinations of mechanisms at the level of individuals, processes at the population level, and patterns of coexistence rather than just one level of this hierarchy.
The Mechanism of Competition for Pollination between Two Forest Herbs
TLDR
These plant species exhibit little or no competition through pollinator preference, and in some natural populations, however, visits to S. pubera are frequently immediately preceded by a visit to C. virginica, and a flower receives less conspecific pollen and produces fewer seeds following such an interspecific visit.
Pollinator Sharing and Seed Set of Stellaria pubera: Competition for Pollination
TLDR
Competition for pollination appears to be one of several selective forces that act on blooming time of S. pubera plants forced to bloom early significantly more than that of control plants.
Competition for Pollinators between Simultaneously Flowering Species
TLDR
The outcome of interspecific competition was analyzed with a simple two-species model and found that an increase in pollinator constancy to a given plant species retards the elimination of the rarer species.
...
...