scholarly journals Spatiotemporal Variations in Seed Set and Pollen Limitation in Populations of the Rare Generalist Species Polemonium caeruleum in Poland

2022 ◽  
Vol 12 ◽  
Author(s):  
Justyna Ryniewicz ◽  
Katarzyna Roguz ◽  
Paweł Mirski ◽  
Emilia Brzosko ◽  
Mateusz Skłodowski ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Population Size ◽  
Seed Production ◽  
Seed Set ◽  
Pollen Limitation ◽  
Monthly Precipitation ◽  
Small Populations ◽  
Flower Visitors ◽  
Visitation Frequency ◽  
Average Monthly Precipitation

A vast majority of angiosperms are pollinated by animals, and a decline in the number and diversity of insects often affects plant reproduction through pollen limitation. This phenomenon may be particularly severe in rare plant species, whose populations are shrinking. Here, we examined the variability in factors shaping reproductive success and pollen limitation in red-listed Polemonium caeruleum L. During a 5-year study in several populations of P. caeruleum (7–15, depending on year), we assessed the degree of pollen limitation based on differences in seed set between open-pollinated (control) and hand-pollinated flowers. We analysed the effects of flower visitors, population size, and meteorological data on plant reproductive success and pollen limitation. Our study showed that pollen limitation rarely affected P. caeruleum populations, and was present mainly in small populations. Pollen limitation index was negatively affected by the size of population, visitation frequency of all insects, and when considering the visitation frequency of individual groups, also by honeybee visits. Seed production in control treatment was positively influenced by the population size, average monthly precipitation in June and visits of hoverflies, while visits of honeybees, average monthly temperature in September, and average monthly precipitation in August influenced seed production negatively. As generalist plant P. caeruleum can be pollinated by diverse insect groups, however, in small populations their main visitors, the honeybees and bumblebees, may be less attracted, eventually leading to the disappearance of these populations. In pollination of P. caeruleum managed honeybees may play a dual role: while they are the most frequent and efficient flower visitors, their presence decreases seed set in open-pollinated flowers, which is most probably related to efficient pollen collection by these insects.

Pollen limitation and reproduction varies with population size in experimental populations of Sabatia angularis (Gentianaceae)

Botany ◽  
2009 ◽  
Vol 87 (3) ◽  
pp. 330-338 ◽  
Author(s):  
Rachel B. Spigler ◽  
Shu-Mei Chang
Keyword(s):  
Reproductive Success ◽  
Population Size ◽  
Intraspecific Competition ◽  
Seed Set ◽  
Pollen Limitation ◽  
Small Populations ◽  
Plant Populations ◽  
Large Populations ◽  
Fruit And Seed Set ◽  
Supplemental Pollination

Individuals in large plant populations are expected to benefit from increased reproductive success relative to those in small populations because of the facilitative effects of large aggregations on pollination. As populations become small, the inability to attract sufficient numbers of pollinators can reduce reproduction via pollen limitation. This study experimentally tested whether such trends occur for the herbaceous biennial Sabatia angularis (L.) Pursh (Gentianaceae). We created artificial populations of varying size consisting of potted S. angularis plants in two field sites to determine whether population size affected mean fruit and seed set. We also examined whether population size affected the degree of pollen limitation using a supplemental pollination design in one of the sites. Our results showed that, on average, seed set was lower in large populations, not small populations, of S. angularis and that this result may be due to increased pollen limitation in large populations. We suggest that in certain contexts, small populations may enjoy reproductive advantages over large populations by escaping intraspecific competition for pollinators.

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.

scholarly journals Frequency of flower visitors and achene production increase with rising population size in the self-incompatible herb Centaurea scabiosa (Asteraceae)

Plant Ecology ◽  
2021 ◽  
Vol 222 (5) ◽  
pp. 613-623
Author(s):  
Stefan Abrahamczyk ◽  
Mirjam Thielen ◽  
Maximilian Weigend
Keyword(s):  
Population Size ◽  
Plant Species ◽  
Clonal Plant ◽  
Current Status ◽  
Small Populations ◽  
Flower Visitors ◽  
Local Populations ◽  
Flower Visitation ◽  
Visitation Frequency ◽  
Achene Production

AbstractSelf-incompatible, non-clonal plant species are especially dependent on the activity of flower visitors for seed production. Therefore, populations of these plants are vulnerable to a reduced flower visitation rates, but also to increased isolation by extinction of local populations. To study how local populations of Centaurea scabiosa, a self-incompatible, bee-pollinated herb species changed over time in the region of Bonn, we collected historical population records in the area and investigated their current status. We found that more than half of the subpopulations mentioned in the literature between 1950 and 2012 (38 of 65) have since disappeared. Small populations were most vulnerable, whereas medium to large populations increased in size. In a second step, we studied visitation frequencies and achene production and weight across 14 extant populations. We found that both flower visitation frequency and achene production were positively related to population size. Achene weight was neither related to the frequency of flower visitors nor to achene production. These results clearly indicate that reduced pollen transfer and lower pollination rates may contribute to local extinction in small populations of Centaurea scabiosa. Overall our results call for an intensified monitoring of the populations of self-incompatible plant species.

scholarly journals Comparative effects of pollen limitation, floral traits and pollinators on reproductive success of Hedysarum scoparium Fisch. et Mey. in different habitats

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Min Chen ◽  
Xue-Yong Zhao ◽  
Xiao-An Zuo ◽  
Shao-Kun Wang ◽  
Hao Qu ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Seed Set ◽  
Pollen Limitation ◽  
Positive Association ◽  
Floral Traits ◽  
Limiting Factor ◽  
Pollinator Visitation ◽  
Open Flower ◽  
Visitation Frequency ◽  
The Difference

Abstract Background Reproduction in most flowering plants may be limited because of the decreased visitation or activity of pollinators in fragmented habitats. Hedysarum scoparium Fisch. et Mey. is an arid region shrub with ecological importance. We explored the pollen limitation and seed set of Hedysarum scoparium in fragmented and restored environments, and examined whether pollen limitation is a significant limiting factor for seed set. We also compared floral traits and pollinator visitation between both habitats, and we determined the difference of floral traits and pollinators influenced reproductive success in Hedysarum scoparium. Results Our results indicated that supplementation with pollen significantly increased seed set per flower, which is pollen-limited in this species. Furthermore, there was greater seed set of the hand cross-pollination group in the restored habitat compared to the fragmented environment. More visits by Apis mellifera were recorded in the restored habitats, which may explain the difference in seed production between the fragmented and restored habitats. Conclusions In this study, a positive association between pollinator visitation frequency and open flower number was observed. The findings of this study are important for experimentally quantifying the effects of floral traits and pollinators on plant reproductive success in different habitats.

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.

Visitation frequency of Melampyrum roseum var. japonicum (Scrophulariaceae) by three bumblebee species and its relation to pollination efficiency

2001 ◽  
Vol 79 (10) ◽  
pp. 1167-1174 ◽  
Author(s):  
Kayako Hiei ◽  
Kazuo Suzuki
Keyword(s):  
Reproductive Success ◽  
Seed Set ◽  
Pollination Efficiency ◽  
Experimental Conditions ◽  
Bumblebee Species ◽  
Single Visit ◽  
Pollination Effectiveness ◽  
Visitation Frequency ◽  
Pollen Removal

The efficiency of pollination of Melampyrum roseum Maximowicz var. japonicum Franchet et Savatier by three bumblebee species, Bombus consobrinus Vogt, Bombus diversus Smith, and Bombus honshuensis Tkalců, which differ especially in proboscis length, was examined under experimental conditions where visitation frequencies were controlled. First, we found that B. honshuensis, with the shortest proboscis, deposited the most pollen per stigma, resulting in the highest seed set in single visit experiments among the three bumblebee species, while B. diversus removed the most pollen from the anthers. The morphological match between pollinators and flowers was found to be an important factor affecting the per-visit pollination intensity mentioned above. Second, we found that seed set and pollen removal increased when flowers were visited twice by any of the three bumblebee species and that the differences among the three bumblebee species disappeared. When flowers were visited three or four times, the seed set and pollen removal did not increase further. These findings indicate that pollination effectiveness may differ among the bumblebee species only when flowers are infrequently visited by any of the bumblebee species.Key words: Melampyrum roseum, bumblebees, pollination efficiency, reproductive success, seed set, visitation frequency.

scholarly journals Inbreeding and inbreeding depression of Paeonia decomposita (Paeoniaceae), a threatened endemic plant to China

2019 ◽  
Vol 60 (1) ◽  
Author(s):  
Shi-Quan Wang
Keyword(s):  
Seed Production ◽  
Inbreeding Depression ◽  
Evolutionary Biology ◽  
Seed Set ◽  
Extinction Risk ◽  
Small Populations ◽  
Endemic Plant ◽  
Pollinator Limitation ◽  
Potential Threat ◽  
Selfed Progeny

Abstract Background Small populations are predominantly vulnerable to inbreeding and inbreeding depression (ID). Owing to increased levels of inbreeding on individuals in small populations, ID could decrease the population growth rate, as well as its effective size, and exacerbate the extinction risk. Inbreeding depression remains a crucial area of research in conservation biology, ecology, and evolutionary biology. This study aims to elucidate the reproductive biology, inbreeding, and ID of Paeonia decomposita and to conserve, manage, and improve them better in the future. Results Paeonia decomposita belongs to a xenogamous category and is partially self-compatible; moreover, it requires pollinators for seed production. Lately, the occurrence of pollination and pollinator limitations has affected the seed set. Low seed set primarily correlated with an abnormality of meiosis in the pollen mother cell, moderate to low genetic diversity, drought and extreme weather, pollinator limitation, or carpel space limit. One of the primary reasons for endangered mechanism in P. decomposita is the low seed set under natural conditions. The cumulative value of ID was positive, and outcrossed progeny outperformed selfed progeny. Conclusions Paeonia decomposita requires pollinators to ensure seed production either through autogamy, geitonogamy, or allogamy. It is both allogamous and partially self-compatible, as well as a successful outcrosser. Inbreeding occurs frequently and results in ID, which imposes a potential threat to the survival of populations. Besides, it needs conservation via in situ and natural return methods.

Pollen limitation in an experimental population of the wild radish Raphanus raphanistrum

1997 ◽  
Vol 75 (1) ◽  
pp. 72-73
Author(s):  
Karin S. Pfennig ◽  
Jeffrey K. Conner
Keyword(s):  
Reproductive Success ◽  
Key Words ◽  
Fruit Set ◽  
Seed Set ◽  
Pollen Limitation ◽  
Experimental Population ◽  
Wild Radish ◽  
Raphanus Raphanistrum ◽  
Female Fitness ◽  
Female Reproductive Success

Experimental hand-pollinations were performed on a sample of wild radish, Raphanus raphanistrum, to determine whether female reproductive success was pollen limited. Fruit set was found to increase with receipt of supplemental pollen, but seed set did not. These results contradict findings in another Raphanus species but are expected if seeds are aborted or matured in packages. Key words: pollen limitation, Raphanus raphanistrum, female fitness.

scholarly journals Reproductive ecology of the distylous species Houstonia longifolia: implications for conservation of a rare species

Botany ◽  
2016 ◽  
Vol 94 (10) ◽  
pp. 983-992
Author(s):  
Jennine L.M. Pedersen ◽  
S. Ellen Macdonald ◽  
Scott E. Nielsen
Keyword(s):  
Population Size ◽  
Seed Production ◽  
Local Density ◽  
Plant Size ◽  
Small Populations ◽  
Range Limit ◽  
Large Populations ◽  
Conservation Actions ◽  
Morph Ratios ◽  
Morph Type

Distylous species typically experience self-incompatibility with one morph often having partial self-compatibility. Small populations may therefore experience greater rates of selfing/intramorph crosses leading to skewed morph ratios and reduced seed production. For the distylous species Houstonia longifolia Gaertn. (“imperiled” at its northwestern range limit in Alberta), we examined whether small populations were morph-biased and whether seed production was affected by population size, local density, plant size, morph type, and surrounding morph ratio. For focal plants in several populations, we measured size (height, number of stems) and local density (1 m2) of pins and thrums, with the focal plants collected for seed counts. Population size was estimated from densities in systematically located quadrats in each population. Morph ratios were pin-biased in small populations but were even to slightly thrum-biased in large populations. The critical population size for maintaining an equal morph ratio was ∼726 plants. Seed production was most influenced by the interaction between morph type and surrounding morph ratio, which were themselves influenced by population size (Allee effect). Seed production increased for thrums but decreased for pins as the proportion of surrounding pins increased, suggesting strong incompatibility. These results provide guidance on population size and morph ratios for conservation actions.

scholarly journals Pollinator limitation affects low reproductive success in populations of nectarless orchid in the Biebrza National Park

2017 ◽  
Vol 70 (1) ◽  
Author(s):  
Emilia Brzosko ◽  
Beata Ostrowiecka ◽  
Paweł Mirski ◽  
Edyta Jermakowicz ◽  
Izabela Tałałaj ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Population Size ◽  
National Park ◽  
Pollen Limitation ◽  
Floral Display ◽  
Pollinator Limitation ◽  
Population Number ◽  
Pollination Success ◽  
Ne Poland ◽  
Conservation Actions

The deficiency of pollinators is indicated as the main factor limiting fruit set in orchids. Nectariferous species are more successful in setting fruits than nectarless species. In the present study, we tested whether pollinator limitation lowers reproductive success in populations of <em>Cypripedium calceolus</em> on environmental islands in the Biebrza National Park, NE Poland. Moreover, we analyzed how population size and structure affect pollination success. Our observations and results of experiments document the low level of fruiting in populations of nectarless <em>C. calceolus</em> (9.2% on average) and strong pollen limitation. Generally, we noted a positive relationship between pollination success and all parameters of population size (measured by both occupied area and number of clumps or shoots) and parameters measuring floral display (number of flowers in population, number of flowers in clumps, spatial structure of flowering shoots). We suggest that information about factors influencing the reproductive success of this endangered species may be useful for planning appropriate conservation actions.

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