Distance-dependent pollen limitation of seed set in some insect-pollinated dioecious plants

2005 ◽  
Vol 28 (3) ◽  
pp. 331-335 ◽  
Author(s):  
Tom J. de Jong ◽  
Judith C. Batenburg ◽  
Peter G.L. Klinkhamer
Keyword(s):  
Seed Set ◽  
Pollen Limitation ◽  
Dioecious Plants

The influence of floral morph ratios and low plant density on mating and fertility in a tristylous colonizing species

Botany ◽  
2018 ◽  
Vol 96 (8) ◽  
pp. 533-545 ◽  
Author(s):  
Christopher M. Balogh ◽  
Spencer C.H. Barrett
Keyword(s):  
Field Experiment ◽  
Seed Set ◽  
Plant Density ◽  
Pollen Limitation ◽  
Lythrum Salicaria ◽  
Long Distance ◽  
Experimental Conditions ◽  
Wide Range ◽  
Morph Ratios ◽  
Floral Morph

Sexual reproduction in heterostylous populations may be vulnerable to demographic conditions because of the small number of mating types in populations. Here, we investigate mating and fertility under natural and experimental conditions in tristylous Lythrum salicaria L., an invasive species that exhibits a wide range of floral morph ratios and demographic contexts. We grew 147 open-pollinated seed families from six populations with different morph structures to estimate intermorph mating (d). In a field experiment, we used progeny ratios from 47 spatially isolated individuals to estimate d, and measured the intensity of pollen limitation experienced by the morphs. The M- and S-morphs experienced high rates of d, regardless of population size or morph ratio. Estimates for the L-morph revealed low levels of intramorph mating in three dimorphic and two trimorphic populations, but near complete intramorph mating in a monomorphic population. Despite high levels of intermorph mating in the field experiment, the morphs experienced significant pollen limitation of fruit and seed set, but this did not differ in intensity among the morphs. Our field experiment demonstrates that although plant isolation was associated with pollen limitation of seed set, “long-distance” bee-mediated pollen flow served to maintain intermorph mating. Tristyly in L. salicaria is remarkably robust to the demographic variation associated with colonization.

Predator Effects on Plant-Pollinator Interactions, Plant Reproduction, Mating Systems, and Evolution

2020 ◽  
Vol 51 (1) ◽  
pp. 319-340
Author(s):  
Amanda D. Benoit ◽  
Susan Kalisz
Keyword(s):  
Mating Systems ◽  
Seed Set ◽  
Pollen Limitation ◽  
Plant Traits ◽  
Plant Reproduction ◽  
Trophic Levels ◽  
Interaction Networks ◽  
Pollinator Abundance ◽  
Plant Pollinator ◽  
Predator Effects

Plants are the foundation of the food web and therefore interact directly and indirectly with myriad organisms at higher trophic levels. They directly provide nourishment to mutualistic and antagonistic primary consumers (e.g., pollinators and herbivores), which in turn are consumed by predators. These interactions produce cascading indirect effects on plants (either trait-mediated or density-mediated). We review how predators affect plant-pollinator interactions and thus how predators indirectly affect plant reproduction, fitness, mating systems, and trait evolution. Predators can influence pollinator abundance and foraging behavior. In many cases, predators cause pollinators to visit plants less frequently and for shorter durations. This decline in visitation can lead to pollen limitation and decreased seed set. However, alternative outcomes can result due to differences in predator, pollinator, and plant functional traits as well as due to altered interaction networks with plant enemies. Furthermore, predators may indirectly affect the evolution of plant traits and mating systems.

Pollen limitation and seed set associated with year-to-year variation in flowering of Gmelina arborea in a natural tropical forest

Grana ◽  
2019 ◽  
Vol 58 (2) ◽  
pp. 133-143 ◽  
Author(s):  
Vinod Prasad Khanduri ◽  
Kewat Sanjay Kumar ◽  
Chandra Mohan Sharma ◽  
Manoj Kumar Riyal ◽  
Kalpataru Kar
Keyword(s):  
Tropical Forest ◽  
Seed Set ◽  
Pollen Limitation ◽  
Gmelina Arborea

The reproductive ecology of island populations of distylous Menyanthes trifoliata (Menyanthaceae)

1998 ◽  
Vol 76 (5) ◽  
pp. 818-828 ◽  
Author(s):  
Faye L Thompson ◽  
Luise A Hermanutz ◽  
David J Innes
Keyword(s):  
Seed Set ◽  
Aquatic Macrophyte ◽  
Pollen Limitation ◽  
Bimodal Distribution ◽  
Stabilizing Selection ◽  
Long Distance ◽  
Anther Length ◽  
Reciprocal Arrangement ◽  
Fruit And Seed Set ◽  
Menyanthes Trifoliata

Menyanthes trifoliata L. is a distylous, clonal aquatic macrophyte found in shallow bogs and river margins throughout the boreal ecosystem, including the island of Newfoundland. A combination of long-distance dispersal and colonization after deglaciation, and pollen limitation resulting from reduced pollinator diversity and abundance documented on islands, predicts the breakdown of heterostyly to favour the establishment of self-compatible homostyles on islands. To test if self-fertilizing homostyles have been selected, variation in floral characters and compatibility relationships were examined in M. trifoliata populations from the Avalon Peninsula of Newfoundland. Morph ratio and its effect on fruit and seed set were examined in nine populations. Of the seven dimorphic populations, morphs occurred in a 1:1 ratio in four populations and deviated significantly from a 1:1 ratio in three populations. The two populations monomorphic for either pin or thrum morphs set few fruits or seeds (<15%). A strictly reciprocal arrangement of stigma height and anther length was not observed between pin and thrum morphs in the majority of populations studied. Stigma-anther separation showed a bimodal distribution with few intermediate "homostylous" flowers, rather than the discreet bimodal distribution typical of distylous species. Fruit and seed set were high (>60%) in equal morph ratio populations and were not significantly correlated to stigma-anther separation, indicating that there was no selective advantage of being homostylous. All three populations tested were highly self-incompatible, confirming that there has not been a breakdown of heterostyly on the island of Newfoundland. A reduced pollinator fauna typical of island environments may have relaxed stabilizing selection for strict herkogamy between floral morphs, resulting in the observed lack of reciprocity.Key words: Menyanthes trifoliata, distyly, homostyle, reciprocal herkogamy, clonal aquatic macrophyte, island of Newfoundland.

Pollination services provided by various size classes of flower visitors to Eucalyptus globulus ssp. globulus (Myrtaceae)

2004 ◽  
Vol 52 (3) ◽  
pp. 353 ◽  
Author(s):  
A. B. Hingston ◽  
B. M. Potts ◽  
P. B. McQuillan
Keyword(s):  
Seed Production ◽  
Eucalyptus Globulus ◽  
Seed Set ◽  
Pollen Limitation ◽  
Pollination Services ◽  
Flower Visitors ◽  
Large Numbers ◽  
Introduced Honeybee ◽  
Commercially Important ◽  
Almost All

Flowers of the commercially important tree Eucalyptus globulus Labill. ssp. globulus were visited by a wide variety of insects and birds within its natural distribution. Flowers were visited so frequently that most available nectar was consumed, but seed production within 5 m of the ground was consistently far less than the maximum possible, indicating the presence of large numbers of inefficient pollinators and few efficient pollinators. Pollen limitation was more severe on fully self-incompatible trees than on partially self-compatible trees, demonstrating that pollinator inefficiency resulted from infrequent outcrossing rather than inability to deposit pollen on stigmas. The flower visitors that were responsible for almost all nectar consumption from flowers within 5 m of the ground were insects that were able to permeate cages with 5-mm apertures but not cages with 1-mm apertures, the most abundant of which was the introduced honeybee Apis mellifera L. These insects contributed less than 20% of the maximum possible seed set, indicating that they were inefficient pollinators. Birds and smaller insects made lesser contributions to seed production, but consumed little nectar within 5 m of the ground. However, anthophilous birds appeared to mostly forage higher in the trees and probably consumed more nectar from, and provided more pollination services to, flowers higher in the trees.

Causes of Low Fruit and Seed Set in Bird-Pollinated Anagyris foetida (Leguminosae): Pollen Limitation and Other Extrinsic Factors

2009 ◽  
Vol 45 (1) ◽  
pp. 77-94 ◽  
Author(s):  
Francisco J. Valtueña ◽  
Ana Ortega-Olivencia ◽  
Tomás Rodríguez-Riaño ◽  
Josefa López
Keyword(s):  
Seed Set ◽  
Pollen Limitation ◽  
Extrinsic Factors ◽  
Fruit And Seed Set

scholarly journals The interplay between ovule number, pollination and resources as determinants of seed set in a modular plant

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5384 ◽  
Author(s):  
Marina M. Strelin ◽  
Marcelo A. Aizen
Keyword(s):  
Resource Allocation ◽  
Seed Production ◽  
Seed Set ◽  
Pollen Limitation ◽  
Rubus Idaeus ◽  
Physiological Integration ◽  
Open Pollination ◽  
Plant Resources ◽  
Plant Seed ◽  
Ovule Number

BackgroundA classical dichotomous perspective proposes that either pollination or plant resources limit seed production. However, ovule number could also be limiting when pollination results in complete ovule fertilization and there are more plant resources available than needed to develop seeds. Moreover, this dichotomous view assumes that all flowers of a plant have equal access to a shared pool of resources, although these are frequently compartmentalized within plant modules, for example, inflorescences. How ovule number, pollination and resources affect seed production in physiologically-compartmentalized rather than physiologically-integrated plants has yet to be explored. We used raspberry (Rubus idaeus) to address this question.MethodsWe first assessed if ovule number affected the fraction of ovules that develop into seed (i.e., seed set) and whether this effect related to the extent of physiological integration among flowers within plants. This was achieved by statistically testing predictions on the sign and level of plant organization (i.e., among flowers within inflorescences, among inflorescences within ramets, and among ramets) of the relation between ovule number and seed set given different degrees of physiological integration. We then explored whether the relation between ovule number and seed set was affected by plant age (used here as a surrogate of resource availability) and pollination intensity (open-pollination vs. exclusion).ResultsWithin inflorescences, flowers with more ovules set a larger fraction of seeds. On the other hand, seed set at the inflorescence level was negatively related to the average number of ovules per flower. Seed set increased with ovule number and open-pollination, and decreased with ramet age. However, ovule number explained more variation in seed set than ramet age and pollination treatment. Ramet age affected the strength of the relation of seed set to ovule number, which was stronger in old than young ramets. Pollination did not alter the strength of this relation to any significant extent.DiscussionResults reveal the importance of ovule number as an overriding factor affecting seed set. Within inflorescences, resources appear to be differentially allocated to developing fruits from flowers with many ovules. This is consistent with the fact that in the raspberry a large proportion of the carbon invested in fruit development is fixed by the inflorescence subtending leaf. Differential resource allocation to flowers with many ovules is not affected by pollinator exclusion, being stronger in resource-exhausted ramets. This suggests that the effects of pollen limitation and resource allocation are compartmentalized at the inflorescence level. Consequently, modular plants can be viewed as reproductive mosaics where either ovule number, pollination or resources limit the number of seeds set by different flowers, so that improvements in any of them could increase plant seed production.

scholarly journals Breeding system and pollen limitation in two supergeneralist alien plants invading Mediterranean shrublands

2009 ◽  
Vol 57 (2) ◽  
pp. 109 ◽  
Author(s):  
Ignasi Bartomeus ◽  
Montserrat Vilà
Keyword(s):  
Invasive Plants ◽  
Breeding System ◽  
Seed Set ◽  
Pollen Limitation ◽  
Native Plant ◽  
Pollination Services ◽  
Mediterranean Shrublands ◽  
Hand Pollination ◽  
Hybrid Introgression ◽  
Low Efficiency

Many widely known invasive plants are well integrated into native plant–pollinator networks. Typically, these invaders have entomophilous flowers which are visited by a diverse array of pollinators. The type of breeding system and the role that pollination services play in the reproductive success of invasive plants have, however, received little attention. We studied the breeding system and pollen limitation of two entomophilous invasive plants, Carpobrotus affine acinaciformis and Opuntia stricta, in different Mediterranean coastal localities in north-eastern Spain. Both species are, to some degree self-compatible; however, because of frequent visitation, open pollination increased the seed set in both species by at least 50%. Whereas O. stricta showed no pollen limitation, some populations of C. aff. acinaciformis had a lower seed set in open-pollinated flowers than in flowers where supplementary hand-pollination ensured out-crossing. This local pollen limitation in C. aff. acinaciformis could be due to the low efficiency of its visitors (mainly beetles) or its hybrid status. On the basis of previous studies on Carpobrotus sp. hybrid complexes, we suggest that the variability among sites in the seed set of open-pollinated flowers is caused by different degrees of hybrid introgression. Not withstanding, we found the C. aff. acinaciformis seed sets studied were higher than those reported in other regions. Further research is needed to assess the invasion potential of these hybrids in Mediterranean shrublands.

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