scholarly journals Nectar robbers pollinate flowers with sexual organs hidden within corollas in distylous Primula secundiflora (Primulaceae)

2010 ◽  
Vol 6 (6) ◽  
pp. 785-787 ◽  
Author(s):  
Xing-Fu Zhu ◽  
Jin-Peng Wan ◽  
Qing-Jun Li
Keyword(s):  
Pollen Grains ◽  
Bumble Bees ◽  
Pollen Flow ◽  
Selective Agent ◽  
Male Fitness ◽  
Seed Number ◽  
Female Fitness ◽  
Fresh Pollen ◽  
Nectar Robbers

Nectar robbers are thought rarely to pollinate flowers, especially those with sexual organs hidden within corollas. In this study, we examined whether robbers pollinate flowers of distylous Primula secundiflora . Distylous plants have two floral morphs. Pin flowers have long styles and short stamens, and thrum flowers have short styles and long stamens. Flowers of P. secundiflora were commonly robbed by bumble-bees, and robbing holes were always situated between high and low sexual organs for both floral morphs. We observed that pollen grains of pin flowers were removed while thrum flowers received fresh pollen grains immediately after flowers were robbed. We manipulated flowers so that only nectar robbers could visit them. This resulted in 98 per cent of thrum flowers and 6 per cent of pin flowers setting fruit, and seed number per thrum fruit was also significantly higher than per pin fruit. Our findings suggest that nectar robbers transfer pollen from pin flowers to thrum flowers effectively, and consequently increase male fitness of the pin morph and female fitness of the thrum morph. Such asymmetrical pollen flow caused by nectar robbers may act as an important selective agent in floral fitness and evolution of distyly.

scholarly journals Landscape Enhancements in Apple Orchards: Higher Bumble Bee Queen Species Richness, but No Effect on Apple Quality

Insects ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 421
Author(s):  
Amélie Gervais ◽  
Marc Bélisle ◽  
Marc J. Mazerolle ◽  
Valérie Fournier
Keyword(s):  
Species Richness ◽  
Bumble Bees ◽  
Bumble Bee ◽  
Pesticide Use ◽  
Apple Orchards ◽  
Seed Number ◽  
Apple Production ◽  
Apple Quality ◽  
Effective Pollinators ◽  
Quality Weight

Bumble bees are among the most effective pollinators in orchards during the blooming period, yet they are often threatened by the high levels of pesticide use in apple production. This study aimed to evaluate the influence of landscape enhancements (e.g., hedgerows, flower strips) on bumble bee queens in apple orchards. Bumble bee queens from 12 orchards in southern Québec (Canada) were marked, released, and recaptured in the springs and falls of 2017 to 2019. Half of the 12 orchards had landscape enhancements. Apples were harvested in 2018 and 2019 to compare their quality (weight, diameter, sugar level, and seed number) in sites with and without landscape enhancements. Species richness, as well as the occurrence of three species out of eight, was higher in orchards with landscape enhancements than in orchards without such structures. The occurrence of Bombus ternarius was lower in orchards with high levels of pesticide use. Apples had fewer seeds when collected in orchards with landscape enhancements and were heavier in orchards that used more pesticides. Our work provides additional evidence that landscape enhancements improve bumble bee presence in apple orchards and should therefore be considered as a means to enhance pollination within farms.

scholarly journals Do metrics of sexual selection conform to Bateman's principles in a wind-pollinated plant?

2019 ◽  
Vol 286 (1905) ◽  
pp. 20190532 ◽  
Author(s):  
Jeanne Tonnabel ◽  
Patrice David ◽  
John R. Pannell
Keyword(s):  
Spatial Distribution ◽  
Sexual Selection ◽  
Reproductive Success ◽  
Pollen Dispersal ◽  
Male Fitness ◽  
Female Fitness ◽  
Dioecious Plant ◽  
Common Gardens ◽  
Mate Acquisition ◽  
Mercurialis Annua

Bateman's principles posit that male fitness varies more, and relies more on mate acquisition, than female fitness. While Bateman's principles should apply to any organism producing gametes of variable sizes, their application to plants is potentially complicated by the high levels of polyandry suspected for plants, and by variation in the spatial distribution of prospective mates. Here we quantify the intensity of sexual selection by classical Bateman metrics using two common gardens of the wind-pollinated dioecious plant Mercurialis annua . Consistent with Bateman's principles, males displayed significantly positive Bateman gradients (a regression of fitness on mate number), whereas the reproductive success of females was independent of their ability to access mates. A large part of male fitness was explained by their mate number, which in turn was associated with males' abilities to disperse pollen. Our results suggest that sexual selection can act in plant species in much the same way as in many animals, increasing the number of mates through traits that promote pollen dispersal.

scholarly journals Effect of high temperature on the reproductive development of chickpea genotypes under controlled environments

2012 ◽  
Vol 39 (12) ◽  
pp. 1009 ◽  
Author(s):  
Viola Devasirvatham ◽  
Pooran M. Gaur ◽  
Nalini Mallikarjuna ◽  
Raju N. Tokachichu ◽  
Richard M. Trethowan ◽  
...  
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Pollen Germination ◽  
Pollen Viability ◽  
Pollen Grains ◽  
High Temperature Stress ◽  
Pollen Production ◽  
Seed Number ◽  
Controlled Environments

High temperature during the reproductive stage in chickpea (Cicer arietinum L.) is a major cause of yield loss. The objective of this research was to determine whether that variation can be explained by differences in anther and pollen development under heat stress: the effect of high temperature during the pre- and post-anthesis periods on pollen viability, pollen germination in a medium, pollen germination on the stigma, pollen tube growth and pod set in a heat-tolerant (ICCV 92944) and a heat-sensitive (ICC 5912) genotype was studied. The plants were evaluated under heat stress and non-heat stress conditions in controlled environments. High temperature stress (29/16°C to 40/25°C) was gradually applied at flowering to study pollen viability and stigma receptivity including flower production, pod set and seed number. This was compared with a non-stress treatment (27/16°C). The high temperatures reduced pod set by reducing pollen viability and pollen production per flower. The ICCV 92944 pollen was viable at 35/20°C (41% fertile) and at 40/25°C (13% fertile), whereas ICC 5912 pollen was completely sterile at 35/20°C with no in vitro germination and no germination on the stigma. However, the stigma of ICC 5912 remained receptive at 35/20°C and non-stressed pollen (27/16°C) germinated on it during reciprocal crossing. These data indicate that pollen grains were more sensitive to high temperature than the stigma in chickpea. High temperature also reduced pollen production per flower, % pollen germination, pod set and seed number.

scholarly journals Sibling quality and the haplodiploidy hypothesis

2020 ◽  
Vol 16 (3) ◽  
pp. 20190764 ◽  
Author(s):  
P. Kennedy ◽  
A. N. Radford
Keyword(s):  
Sex Ratio ◽  
Kin Selection ◽  
Selection Model ◽  
Male Fitness ◽  
Female Fitness ◽  
Evolution Of Eusociality ◽  
Insect Biology ◽  
Relatedness Asymmetry

The ‘haplodiploidy hypothesis’ argues that haplodiploid inheritance in bees, wasps, and ants generates relatedness asymmetries that promote the evolution of altruism by females, who are less related to their offspring than to their sisters (‘supersister’ relatedness). However, a consensus holds that relatedness asymmetry can only drive the evolution of eusociality if workers can direct their help preferentially to sisters over brothers, either through sex-ratio biases or a pre-existing ability to discriminate sexes among the brood. We show via a kin selection model that a simple feature of insect biology can promote the origin of workers in haplodiploids without requiring either condition. In insects in which females must found and provision new nests, body quality may have a stronger influence on female fitness than on male fitness. If altruism boosts the quality of all larval siblings, sisters may, therefore, benefit more than brothers from receiving the same amount of help. Accordingly, the benefits of altruism would fall disproportionately on supersisters in haplodiploids. Haplodiploid females should be more prone to altruism than diplodiploid females or males of either ploidy when altruism elevates female fitness especially, and even when altruists are blind to sibling sex.

scholarly journals Evaluation of Selected Ornamental Asteraceae as a Pollen Source for Urban Bees

2016 ◽  
Vol 60 (2) ◽  
pp. 179-192 ◽  
Author(s):  
Anna Wróblewska ◽  
Ernest Stawiarz ◽  
Marzena Masierowska
Keyword(s):  
Honey Bees ◽  
Pollen Grains ◽  
Bumble Bees ◽  
Floral Resources ◽  
Tagetes Patula ◽  
Single Plant ◽  
Calendula Officinalis ◽  
Wild Bees ◽  
Se Poland ◽  
Urban Conditions

Abstract Offering more floral resources for urban bees can be achieved by growing ornamental bee plants. The aim of the present study was to evaluate selected Asteraceae (Calendula officinalis ‘Persimmon Beauty’ and ‘Santana’, Centaurea macrocephala, Cosmos sulphureus, Dahlia pinnata, Tagetes patula, Tithonia rotundifolia, and Zinnia elegans) as pollen sources for pollinators. Under urban conditions in Lublin, SE Poland, the investigated plants flowered from late June to the end of October. The mass of pollen produced in florets and capitula was found to be species-related. The highest pollen amounts per 10 florets (10.1 mg) as well as per capitulum (249.7 mg) were found for C. macrocephala. The mass of pollen yielded by a single plant depended on both the pollen mass delivered per disk florets and the proportion of disk florets in capitulum, and the flowering abundance of the plants. A single plant of D. pinnata and a single plant of T. rotundifolia each produced the largest pollen mass. Mean pollen yield per 1m2 of a plot ranged from 6.2 g (Z. elegans) to 60.7 g (D. pinnata). Pollen grains are tricolporate, with echinate exine, medium or small in size. They can be categorised as oblatespherical, spherical, and prolatespherical. The principal visitors to C. macrocephala, C. sulphureus, and C. officinalis were honey bees, whereas bumble bees dominated on T. rotundifolia and D. pinnata. A magnet plant for butterflies was Z. elegans. Among the investigated species, D. pinnata, C. macrocephala, and T. rotundifolia were found to be the most valuable sources of pollen flow for managed and wild bees.

scholarly journals Evolution of external female genital mutilation: why do males harm their mates?

2017 ◽  
Vol 4 (11) ◽  
pp. 171195 ◽  
Author(s):  
Pierick Mouginot ◽  
Gabriele Uhl ◽  
Lutz Fromhage
Keyword(s):  
Sperm Competition ◽  
Female Genital Mutilation ◽  
Reproductive Traits ◽  
Sperm Precedence ◽  
Male Fitness ◽  
Fitness Costs ◽  
Female Fitness ◽  
Genital Mutilation ◽  
Female Behaviour ◽  
Female Genital

Sperm competition may select for male reproductive traits that influence female mating or oviposition rate. These traits may induce fitness costs to the female; however, they may be costly for the males as well as any decrease in female fitness also affects male fitness. Male adaptations to sperm competition manipulate females by altering not only female behaviour or physiology, but also female morphology. In orb-weaving spiders, mating may entail mutilation of external structures of the female genitalia, which prevents genital coupling with subsequent males. Here, we present a game theoretical model showing that external female genital mutilation is favoured even under relatively high costs of mutilation, and that it is favoured by a high number of mate encounters per female and last-male sperm precedence.

scholarly journals Pecan Pollen Stored Over a Decade Retains Viability

HortScience ◽  
2002 ◽  
Vol 37 (1) ◽  
pp. 176-177 ◽  
Author(s):  
Darrell Sparks ◽  
I.E. Yates
Keyword(s):  
Liquid Nitrogen ◽  
Pollen Morphology ◽  
Germ Tube ◽  
Pollen Grains ◽  
Carya Illinoinensis ◽  
In Vitro Germination ◽  
Fresh Pollen

In vitro germination of freshly collected pollen and pollen stored 1, 10, 11, 12, and 13 years in liquid nitrogen was examined for `Desirable' pecan [Carya illinoinensis (Wangenh.) C. Koch]. Viability of pollen stored in liquid nitrogen for 1, 10, 11, 12, and 13 years was not diminished in comparison to that of fresh pollen. Morphology of stored pollen grains and the germ tube was normal. Thus, liquid nitrogen may offer a means of haploid preservation of pecan.

Effects of stepped-combustion on fresh pollen grains: Morphoscopic, thermogravimetric, and chemical proxies for the interpretation of archeological charred assemblages

2018 ◽  
Vol 259 ◽  
pp. 142-158 ◽  
Author(s):  
Roberta Pini ◽  
Giulia Furlanetto ◽  
Lorenzo Castellano ◽  
Francesco Saliu ◽  
Agostino Rizzi ◽  
...  
Keyword(s):  
Pollen Grains ◽  
Fresh Pollen

Potential Pollen and Seed Production from Early- and Late-Emerging Common Ragweed in Corn and Soybean

2012 ◽  
Vol 26 (3) ◽  
pp. 510-516 ◽  
Author(s):  
Marie-Josée Simard ◽  
Diane Lyse Benoit
Keyword(s):  
Weed Control ◽  
Seed Production ◽  
Pollen Grains ◽  
Pollen Production ◽  
Female Fitness ◽  
Gender Distribution ◽  
Common Ragweed ◽  
Production Values ◽  
And Gender ◽  
Seeding Emergence

Despite the abundance of common ragweed in crops and the potency of ragweed pollen as an allergen, pollen production in agricultural fields has hardly been evaluated. Our goal was to evaluate pollen and seed production of early- (i.e., plants missed by weed control) and late- (i.e., after weed control) emerging common ragweed growing in corn and soybean. Allocation and gender distribution were also evaluated. The experiment included 2 yr (2008, 2009), three competition treatments, two seeding/emergence dates, three densities, and four replicates. Competition treatments (main plots) included no crop or weeds (bare), corn, or soybean. Crops were glyphosate resistant. Subplots were seeded with common ragweed before or after glyphosate application at densities of 1 (4 m−2), 3 (12 m−2), or 6 (24 m−2) plants per plot. Ragweed plants were harvested in mid-October and measured (aboveground biomass, length of all male inflorescences, stem diameter, and seed production). Based on our estimates, mean (backtransformed from ln[x+ 1]) pollen production values were: 6.25 (bare), 0.74 (corn), and 1.13 (soybean) × 108pollen grains per ragweed. Biomass and diameter were good predictors of ragweed male and female fitness. Plant height was not correlated with maleness. In crops, ragweed gender distribution was shifted toward maleness. Estimations indicate early-emerging (June 18 to 23) ragweed produced three times more pollen than late (July 7 to 11) plants.

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