scholarly journals Herkogamy but not reciprocity is a better predictor of legitimate pollen transfer and fruit set in Jasminum malabaricum, a self-compatible species with stigma-height dimorphism

2020 ◽  
Author(s):  
Shatarupa Ganguly ◽  
Deepak Barua
Keyword(s):  
Reproductive Success ◽  
Fruit Set ◽  
Natural Populations ◽  
Negative Relationship ◽  
Pollen Deposition ◽  
Pollen Transfer ◽  
Style Length ◽  
Individual Level ◽  
Reciprocal Arrangement ◽  
The Relationship

AbstractPremiseReciprocity and herkogamy, morphological traits that define style length polymorphisms, are thought to be critical in determining legitimate inter-morph pollen transfer in plants with style length polymorphism. However, the consequences of individual-level variation in these traits for pollen transfer and reproductive success have rarely been examined, and the relationship between these two fundamental traits remains unexplored.MethodsWe quantified individual-level estimates of herkogamy and reciprocity and tested the assumption that higher herkogamy and reciprocity result in higher legitimate pollen transfer and reproductive success in natural populations of Jasminum malabaricum, a species that exhibits stigma-height dimorphism. Additionally, we examined the relationship between herkogamy and reciprocity to understand potential consequences for avoiding self-pollination and encouraging legitimate pollen deposition.ResultsSurprisingly, reciprocity was not related to pollen load, legitimate pollen fraction or reproductive success. In contrast, herkogamy was positively associated with legitimate pollen fraction and fruit set in the long-styled morph. Interestingly, we observed a negative relationship between herkogamy and reciprocity in the long-styled morph.ConclusionsHerkogamy was more important than reciprocity in increasing legitimate pollen transfer and reproductive success in J. malabaricum. Herkogamy might be particularly important in stabilising species with stigma-height dimorphism and other such polymorphic intermediates with low reciprocity, and this may allow the evolution of reciprocal arrangement of sex organs at a later stage in the pathway towards distyly. The negative relationship between herkogamy and reciprocity suggests a trade-off between avoidance of self-pollen deposition and promotion of legitimate pollen deposition.

scholarly journals Increased variation in sex organ positions can increase reciprocity and pollination success in heterostylous plant populations

2020 ◽  
Author(s):  
Shatarupa Ganguly ◽  
P.M. Shreenidhi ◽  
Deepak Barua
Keyword(s):  
Reproductive Success ◽  
Natural Populations ◽  
Population Variation ◽  
Success For All ◽  
Pollen Transfer ◽  
Plant Populations ◽  
Pollination Success ◽  
Naturally Occurring ◽  
Transfer Success ◽  
The Relationship

AbstractAimsThe reciprocal position of sexual organs in complementary floral morphs is central to our understanding of heterostyly. Reciprocity indices are used to quantify the spatial match between complementary sex organs, but previous indices fail to appropriately account for variation in sex organ positions among individuals in a population. The objective of this study was to examine how reciprocity and consequently reproductive success change with an increase in intra-population variation in sex organ heights. To this end, we formulated a reciprocity index that incorporates variation in sex organ positions among individuals in a population and asked if estimates of reciprocity can predict reproductive success in naturally occurring heterostylous populations.MethodsWe developed a reciprocity index that assumed pollen transfer success equalled one for a perfectly matched stigma-anther pair, and decreased to zero with increasing mismatch. Reciprocity was quantified as the average pollen transfer success for all pair-wise combinations of complementary sex organs in the population. We examined the relationship between intra-population variation and reciprocity using simulated populations that varied in the distribution of sex organ positions, and with empirical data from natural populations. We compared previously proposed indices using the simulated and natural populations, and for a subset of natural populations we tested the ability of the indices to predict reproductive success.Important FindingsIn both simulated and natural populations we observed that when differences between mean anther and stigma heights of complementary morphs are small, increasing intra-population variation in heights resulted in a monotonous decrease in reciprocity. However, when differences between mean complementary anther and stigma heights are larger, reciprocity increased, reached a peak, and then decreased with increasing variation. Previous indices failed to capture this behaviour and were largely insensitive to variation or differences in mean complementary sex organ heights. Seed set was consistently positively related to reciprocity for our index, and for two of the four previous indices. These results highlight the importance of incorporating intra-population variation in sex organ dimensions in quantifying reciprocity, and challenge the current understanding that increasing variation will always decrease reciprocity in heterostylous populations. These results may help explain why heterostylous systems exhibit, and tolerate high amounts of intra-population variation in sex organ heights.

scholarly journals Do abundance and proximity of the alien Impatiens glandulifera affect pollination and reproductive success of two sympatric co-flowering native species?

2012 ◽  
Vol 10 ◽  
pp. 130-139
Author(s):  
Valérie Cawoy ◽  
Mathieu Jonard ◽  
Carolin Mayer ◽  
Anne-Laure Jacquemart
Keyword(s):  
Reproductive Success ◽  
Native Species ◽  
Natural Populations ◽  
Pollen Deposition ◽  
Impatiens Glandulifera ◽  
Insect Behaviour ◽  
Native Flora ◽  
Visitation Rates ◽  
Aconitum Napellus ◽  
Negative Effect

In invasion ecology, potential impacts of aliens on native flora are still under debate. Our aim was to determine the pollinator mediated effects of both proximity and abundance of an alien species on the reproductive success of natives. We chose the highly invasive Impatiens glandulifera and two native species: Epilobium angustifolium and Aconitum napellus ssp. lusitanicum. These species share characteristics allowing for pollination interactions: similar biotopes, overlapping flowering periods and same main pollinators. The effects of abundance (5, 25 and 100 individuals) and proximity (0 and 15 m) of the alien on visitation rate, insect behaviour, pollen deposition and reproductive success of both natives were investigated during 2 flowering seasons. We used centred visitation rates as they can be directly interpreted as a positive or negative effect of the invasive.Both abundance and proximity of the alien increased bumblebee visitation rates to both natives. On the other hand, abundance of the exotic species had a slight negative effect on honeybee visits to natives while its proximity had no effect. The behaviour of bumblebees changed as visitors left significantly more often the native plants for I. glandulifera when its abundance increased. As a consequence of this “inconstancy”, bees deposited considerable quantities of alien pollen on native stigmas. Nevertheless, this interspecific pollen transfer did not decrease seed set in natives. Self-compatibility and high attractiveness of both native species probably alleviate the risk of altered pollinator services and reproductive success due to the invader in natural populations.

scholarly journals Male and female reproductive success in natural and anthropogenic populations of Malaxis monophyllos (L.) Sw. (Orchidaceae)

2015 ◽  
Vol 39 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Edyta Jermakowicz ◽  
Beata Ostrowiecka ◽  
Izabela Tałałaj ◽  
Artur Pliszko ◽  
Agata Kostro-Ambroziak
Keyword(s):  
Reproductive Success ◽  
Fruit Set ◽  
Natural Populations ◽  
Floral Display ◽  
Natural Habitats ◽  
Female Reproductive Success ◽  
Male And Female ◽  
Demographic Processes ◽  
Preliminary Study ◽  
Effective Pollinators

Abstract In the presented study, male and female reproductive success was analyzed in relation to the population size, floral display and pollinators’ availability in natural and anthropogenic populations of the orchid Malaxis monophyllos (L.) Sw. Our results indicated significant differences between all investigated populations in parameters of floral display, including heights and number of flowers per inflorescence, as well the number of flowering individuals and their spatial structure. Additionally, populations differed both in male (pollinia removal) and female (fruit set) reproductive success, but only the fruit set clearly differentiated anthropogenic and natural populations. Despite the average flower number per plant being significantly higher in two of the anthropogenic populations, it was not related to the fruits set, which was significantly lower there. Moreover, our preliminary study concerning the potential pollinators of M. monophyllos showed a higher contribution of flies in natural habitats than in anthropogenic ones. Thus, we can suspect that the main factors influencing the level of female reproductive success in M. monophyllos populations are abundance of effective pollinators, as well as flower visitors, which may have resulted in a different level of pollen discounting in populations. Therefore, further studies concerning breeding system and pollination as important forces that shape demographic processes in M. monophyllos populations are necessary. Our results also indicate that suitable conservation methods in M. monophyllos should always include the preservation of potential pollinators, especially in these new, secondary habitats.

Does Demographic Dissimilarity Matter for Perceived Inclusion? Evidence From Public Sector Employees

2016 ◽  
Vol 37 (1) ◽  
pp. 4-22 ◽  
Author(s):  
Kwang Bin Bae ◽  
Meghna Sabharwal ◽  
Amy E. Smith ◽  
Evan Berman
Keyword(s):  
Public Sector ◽  
Negative Relationship ◽  
Positive Association ◽  
Public Agencies ◽  
Individual Level ◽  
Demographic Group ◽  
Public Sector Employees ◽  
The Status ◽  
The Relationship ◽  
Influence Perceptions

This study examines the relationship between individual dissimilarity and perceptions of organizational inclusion. Data from a national survey of public agencies conducted in Florida and Texas show that gender dissimilarity is negatively associated with perceptions of inclusion and the negative relationship is more acute for men than for women. In contrast, tenure dissimilarity is positively related to perceptions of inclusion and this positive association is more acute for those with longer tenure than for those with shorter tenure. These results suggest that the effect of dissimilarity on the perception of inclusion depends on both the observability of individual-level characteristics and the status of the demographic group. In particular, dissimilarity along characteristics that are easily observable (such as gender) is more likely to influence perceptions of inclusion and dissimilarity is more influential for higher status groups (such as men or long-tenured employees).

scholarly journals Sensitivity of commercial pumpkin yield to potential decline among different groups of pollinating bees

2017 ◽  
Vol 4 (5) ◽  
pp. 170102 ◽  
Author(s):  
Sonja C. Pfister ◽  
Philipp W. Eckerter ◽  
Jens Schirmel ◽  
James E. Cresswell ◽  
Martin H. Entling
Keyword(s):  
Crop Yield ◽  
Fruit Set ◽  
Pollen Grains ◽  
Pollen Deposition ◽  
Insect Pollination ◽  
Study Region ◽  
Flower Visitation ◽  
Pollen Receipt ◽  
The Relationship ◽  
Pollinator Fauna

The yield of animal-pollinated crops is threatened by bee declines, but its precise sensitivity is poorly known. We therefore determined the yield dependence of Hokkaido pumpkin in Germany on insect pollination by quantifying: (i) the relationship between pollen receipt and fruit set and (ii) the cumulative pollen deposition of each pollinator group. We found that approximately 2500 pollen grains per flower were needed to maximize fruit set. At the measured rates of flower visitation, we estimated that bumblebees (21 visits/flower lifetime, 864 grains/visit) or honeybees (123 visits, 260 grains) could individually achieve maximum crop yield, whereas halictid bees are ineffective (11 visits, 16 grains). The pollinator fauna was capable of delivering 20 times the necessary amount of pollen. We therefore estimate that pumpkin yield was not pollination-limited in our study region and that it is currently fairly resilient to single declines of honeybees or wild bumblebees.

scholarly journals Mating system and female reproductive success of the endemic, epiphytic Prosthechea aff. karwinskii (Orchidaceae)

Lankesteriana ◽  
2011 ◽  
Vol 11 (3) ◽  
Author(s):  
Ericka Camacho-Domínguez ◽  
Irene Ávila-Díaz
Keyword(s):  
Reproductive Success ◽  
Mating System ◽  
Sexual Reproduction ◽  
Fruit Set ◽  
Natural Populations ◽  
Fruit Production ◽  
Open Pollination ◽  
Female Reproductive Success ◽  
Hand Pollination ◽  
Northern Portion

Prosthechea aff. karwinskii (Mart.) Soto Arenas & Salazar (unpublished name) is an endemic Mexican epiphytic orchid with a restricted distribution. It occurs in deciduous oak forests, particularly on Quercus deserticola in the northern portion of Michoacán state. Due to their ornamental uses, this and other orchid species have been heavily collected from their natural populations. Learning about the reproductive biology of this species is important, as we may gain knowledge about the probable repercussions of overcollecting on their genetics and ecology. This will be a useful tool for the management and conservation of the species. The objectives were to 1) study the mating system of P. aff. karwinskii, 2) determine if the species requires an external pollinating agent for sexual reproduction, and 3) evaluate female reproductive success of this species. Exclusions (150) were made before anthesis. Once the flowers opened, we applied four pollination treatments: manual selfing, outcrossing, spontaneous autogamy, and open pollination. We subsequently quantified the production of fruits and viability of the seeds. Preliminary results showed that outcrossing and selfing treatments exhibited statistically higher fruit set than spontaneous autogamy and open pollination treatments, meaning that P. aff. karwinskii has the capability to reproduce via self-pollination. Prosthechea aff. karwinskii is pollinator-dependent for sexual reproduction, taking into account that the spontaneous autogamy treatment showed nil fruit production. Female reproductive success in open pollinated flowers was lower compared to fruit set of hand pollination treatments. This indicates that this species, as other species of tropical orchids, is pollination-limited. 

Pollen load, capsule weight, and seed production in three orchid species

1994 ◽  
Vol 72 (2) ◽  
pp. 249-255 ◽  
Author(s):  
H. C. Proctor ◽  
L. D. Harder
Keyword(s):  
Reproductive Success ◽  
Seed Production ◽  
Pollen Deposition ◽  
Pollen Load ◽  
Seed Number ◽  
Orchid Species ◽  
Liquid Suspension ◽  
Ovule Number ◽  
Cypripedium Calceolus ◽  
The Relationship

Relationships between pollen load, seed production, and capsule weight in orchids are important both theoretically and pragmatically. It has been hypothesized that pollen packets (pollinia) evolved in orchids because of selection to produce packages capable of fertilizing all ovules in an ovary; testing this hypothesis requires information about the relationship between pollen load and seed production. As well, because capsules contain thousands to millions of seeds, an easily measured correlate of seed number, such as capsule weight, would be valuable for studies of reproductive success. We hand-pollinated Cypripedium calceolus, Amerorchis rotundifolia, and Calypso bulbosa with different pollen loads, weighed capsules, and estimated seed number by subsampling from liquid suspension. Pollen load affected seed number in Calypso but had no significant effect in Cypripedium or Amerorchis. Capsule weight was positively associated with seed number in all species, but there was considerable variation in R2 across species (from 0.40 to 0.85), indicating that it is unwise to assume that capsule weight is a good measure of relative reproductive success. As well, our data suggest that size of the typical unit of pollen deposition rather than that of the entire pollinarium evolved to match ovule number in orchids. Key words: Orchidaceae, pollen load, capsule weight, seed set.

scholarly journals On being the right size: increased body size is associated with reduced telomere length under natural conditions

2015 ◽  
Vol 282 (1820) ◽  
pp. 20152331 ◽  
Author(s):  
Thor Harald Ringsby ◽  
Henrik Jensen ◽  
Henrik Pärn ◽  
Thomas Kvalnes ◽  
Winnie Boner ◽  
...  
Keyword(s):  
Body Size ◽  
Telomere Length ◽  
Natural Populations ◽  
Negative Relationship ◽  
House Sparrows ◽  
Selection Regime ◽  
Trade Offs ◽  
Length Changes ◽  
The Relationship ◽  
Telomere Dynamics

Evolution of body size is likely to involve trade-offs between body size, growth rate and longevity. Within species, larger body size is associated with faster growth and ageing, and reduced longevity, but the cellular processes driving these relationships are poorly understood. One mechanism that might play a key role in determining optimal body size is the relationship between body size and telomere dynamics. However, we know little about how telomere length is affected when selection for larger size is imposed in natural populations. We report here on the relationship between structural body size and telomere length in wild house sparrows at the beginning and end of a selection regime for larger parent size that was imposed for 4 years in an isolated population of house sparrows. A negative relationship between fledgling size and telomere length was present at the start of the selection; this was extended when fledgling size increased under the selection regime, demonstrating a persistent covariance between structural size and telomere length. Changes in telomere dynamics, either as a correlated trait or a consequence of larger size, could reduce potential longevity and the consequent trade-offs could thereby play an important role in the evolution of optimal body size.

Political Islam, Internet Use and Willingness to Migrate: Evidence from the Arab Barometer

2016 ◽  
Vol 22 (1) ◽  
pp. 73-95 ◽  
Author(s):  
Chiara Falco ◽  
Valentina Rotondi
Keyword(s):  
Internet Use ◽  
Positive Relationship ◽  
Arab World ◽  
Negative Relationship ◽  
Political Islam ◽  
The Internet ◽  
Individual Level ◽  
The Third ◽  
The Relationship

AbstractThis paper investigates the relationship between political Islam, willingness to migrate and Internet use by exploiting the second (2010–2011) and the third (2012–2014) waves of the Arab Barometer. In an effort to explain individual-level willingness to migrate from the Arab world, it investigates the channel through which the more people support political Islam the less they are willing to migrate. At the same time, it explores the fact that the Internet could potentially act as a vehicle of political Islam. Indeed, our findings indicate that there exists a positive relationship between Internet use and individual-level willingness to migrate, while there exists a negative relationship between political Islam and individual-level willingness to migrate. The findings indicate also that there is no significant effect of Internet use on political Islam.

Psychological contract and organizational justice: the role of normative contract

2020 ◽  
Vol 42 (1) ◽  
pp. 17-34 ◽  
Author(s):  
Yolanda Estreder ◽  
Thomas Rigotti ◽  
Inés Tomás ◽  
José Ramos
Keyword(s):  
Organizational Justice ◽  
Psychological Contract ◽  
Negative Relationship ◽  
Organizational Level ◽  
Negative Effects ◽  
Content Type ◽  
Individual Level ◽  
Justice Perceptions ◽  
The Relationship ◽  
Positive Effect

Purpose The purpose of this paper is to examine perceptions of the psychological contract (PC) simultaneously at the individual level (fulfillment of obligations by the organization and PC violation) and the organizational level (normative contract), and their relationship with employees’ evaluations of organizational justice. Based on justice and information processing approaches, the hypothesis is that normative contract has an effect on employees’ perceptions of organizational justice, and also moderates the relationship between PC violation and organizational justice. Design/methodology/approach Multilevel modeling was employed with a multinational sample of 5,338 employees nested in 214 companies. Findings Findings showed that beyond the positive effect of fulfillment of obligations by the organization, PC violation has a strong negative effect on organizational justice. In addition, normative contract has a positive effect on organizational justice, showing that when shared perceptions of normative contract are higher, then the organizational justice perceptions of employees are also higher. Furthermore, the normative contract moderated the relationship between PC violation and organizational justice, showing that the negative relationship of PC violation with organizational justice was stronger when the normative contract was higher. Practical implications Findings suggest that normative contract has effects on organizational justice, and that PC violation had more negative effects on employees’ perceptions of organizational justice perceptions when colleagues’ shared perceptions of fulfillment were higher. This means that social context (shared perceptions in an organization about the PC) has effects on individual perceptions of organizational justice. Companies need to pay attention to detrimental effects on employees who perceive a worse PC than their colleagues do. Originality/value The study extends the current research by demonstrating that employee–employer exchanges are not limited to individual level effects because shared perceptions of PC fulfillment (normative contract) also have relevant effects on employees’ perceptions of organizational justice.

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