scholarly journals Nectar secretion and pollen production in protandrous flowers of Campanula patula L. (Campanulaceae)

2018 ◽  
Vol 71 (1) ◽  
Author(s):  
Bożena Denisow ◽  
Monika Strzałkowska-Abramek ◽  
Małgorzata Wrzesień
Keyword(s):  
Sugar Accumulation ◽  
Reproductive Costs ◽  
Pollen Production ◽  
Nectar Secretion ◽  
Mass Content ◽  
Plastic Response ◽  
Male And Female ◽  
Functional Relationships ◽  
Female Phase ◽  
Male Phase

Nectar secretion was noted both in the male and female floral phases of the protandrous flowers of <em>Campanula patula</em> (Campanulaceae). Female-biased sugar accumulation was evidenced and plasticity in the duration of sexual phases observed. Flowers in the male phase produced twofold less nectar with lower sugar concentrations compared to female-phase flowers. The sugar mass content averaged 0.6 mg ±0.45 <em>SD</em> per flower in the male phase and 1.4 ±0.5 <em>SD</em> per flower in the female phase. The pollen mass averaged 0.16 mg ±0.10 <em>SD</em> per flower. An understanding of the evolution of functional relationships between floral sexes requires consideration of the compensation of the reproductive costs, including the plastic response to interdependent factors, i.e., photosynthesis and growth, the effect of pollinators, pollen robbers, and external environmental forces.

scholarly journals Intraflower variation in nectar secretion: Secretion patterns and pollinator behavior in male- and female-phase flowers

2018 ◽  
Vol 105 (5) ◽  
pp. 842-850 ◽  
Author(s):  
Ando Misaki ◽  
Tomoyuki Itagaki ◽  
Yutaka Matsubara ◽  
Satoki Sakai
Keyword(s):  
Nectar Secretion ◽  
Male And Female ◽  
Pollinator Behavior ◽  
Female Phase

scholarly journals Intraspecific Seasonal Variation of Flowering Synchronization in a Heterodichogamous Tree

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1509
Author(s):  
Noemi Tel-Zur ◽  
Tamar Keasar
Keyword(s):  
Genetic Diversity ◽  
Seasonal Variation ◽  
Phase Duration ◽  
Male And Female ◽  
Flowering Synchrony ◽  
Flowering Season ◽  
Hand Pollination ◽  
Female Phase ◽  
Male Phase ◽  
Phase Differences

Heterodichogamous reproduction in plants involves two flowering morphs, reciprocal in their timing of male and female sexual functions. The degree of synchrony in floral sex phase, within and between individuals of each morph, determines the flowers’ potential fertilization partners. Complete within-morph synchrony enables across-morph mating alone, whereas unsynchronized floral sex phases may allow fertilization within a plant individual (geitonogamy) or within a morph. We documented the disruption of flowering synchrony in the heterodichogamous Ziziphus spina-christi towards the end of its seven-month flowering season. This desert tree has self-incompatible, protandrous, short-lived (2-day) flowers that open before dawn (‘Early’ morph) or around noon (‘Late’ morph). We counted flowers in the male and female phase on flowering branches that were sampled monthly during the 2016–2018 flowering seasons. In 2018, we also tagged flowers and followed their sex-phase distributions over two days at the start, middle, and end of the season. The switch to the female phase was delayed at the end-season (November-December), and 74% of the flowers did not develop beyond their male phase. Differences in male-phase duration resulted in asynchrony among flowers within each tree and among trees of both flowering morphs. Consequently, fertilization between trees of the same morph becomes potentially possible during the end-season. In controlled hand-pollination assays, some within-morph fertilizations set fruit. The end-season breakdown of synchronous flowering generates variability within morphs and populations. We suggest that this variability may potentially enable new mating combinations in a population and enhance its genetic diversity.

Effects of forest fragmentation on assemblages of pollinators and floral visitors to male- and female-phase inflorescences of Astrocaryum mexicanum (Arecaceae) in a Mexican rain forest

2010 ◽  
Vol 27 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Armando Aguirre ◽  
Roger Guevara ◽  
Rodolfo Dirzo
Keyword(s):  
Species Richness ◽  
Forest Fragmentation ◽  
Rain Forest ◽  
Diversity Index ◽  
Fragment Size ◽  
Forest Fragments ◽  
Male And Female ◽  
Female Phase ◽  
Male Phase ◽  
Floral Visitors

Abstract:We examined the consequences of habitat fragmentation on the assemblage of floral visitors and pollinators to male- and female-phase inflorescences of the understorey dominant palm Astrocaryum mexicanum at the Los Tuxtlas tropical rain forest. In six forest fragments ranging from 2 to 700 ha, we collected all floral visitors, pollinators and non-pollinators, to male- and female-phase inflorescences at the time of their greatest activity. We used multivariate and mixed-effects models to explore differences in guild composition between sexual phases of inflorescences and the effects of forest fragment size on several metrics of the assemblages of floral visitors. We detected 228 786 floral visitors, grouped into 57 species, across the six forest fragments. On average, abundance and species richness of floral visitors to female-phase inflorescences were higher than to male-phase ones. Forest fragmentation had no effect on species richness but negatively affected Shannon's diversity index. Overall, the most abundant species of floral visitors were predominantly found in inflorescences of plants from the large fragments. In contrast, most of the less common species were more abundant in the smallest fragments. The abundance of pollinators (those found on inflorescences of both phases and dusted with pollen that was carried to flower stigmas), and the ratio of pollinators to other floral visitors, increased with fragment size in both sexual phases of the inflorescences but these effects were significantly stronger on male-phase inflorescences than on female-phase inflorescences. These results show that tropical forest fragmentation correlates with changes in the composition of flower visitors to a dominant palm, with a reduction in the abundance of pollinators, but that such changes co-vary with the sexual phase of the plants.

scholarly journals Flowering, nectar secretion, pollen shed and insect foraging on Aquilegia vulgaris L. (Ranunculaceae)

2012 ◽  
Vol 65 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Bożena Denisow ◽  
Sebastian Antoń
Keyword(s):  
Reproductive System ◽  
Sugar Yield ◽  
Pollen Production ◽  
Nectar Secretion ◽  
Flower Opening ◽  
Flower Visitors ◽  
Insect Visitation ◽  
Female Phase ◽  
Pollen Shed

This study on blooming biology, nectar secretion, pollen production and insect visitation of <i>Aquilegia vulgaris</i> L. was carried out in 2009 and 2011 in Lublin. The peak of flower opening during the day was between 5.00 and 7.00 (GMT +2). The flowers are protandrous with the female phase beginning approx. on the 3rd day of anthesis. The dynamics of nectar secretion and pollen shed from anthers (progressing from the central part of the androecium outwards) support the reproductive system. The amount of nectar accumulated in the spurs increased from the bud stage and was the highest in the phase with approx. ¾ of dehisced anthers, usually on the 3<sup>rd</sup> day of flower life. Then, towards the end of anthesis, the amount of secreted and accumulated nectar decreased. The number of anthers developed per flower varied from 41 to 61 (mean = 49.1). The mass of pollen per 100 anthers averaged 6.7 mg. Pollen production per flower (mean = 3.28 mg) slightly varied between years and was mainly correlated with the number of developed anthers. Estimated pollen yield was 1.69 g per m<sup>2</sup> and sugar yield 1.22 g per m<sup>2</sup>. Species from the genus <i>Bombus</i> were the main flower visitors, with <i>B. terrestris</i> being the most frequent forager.

Pollination of Amorphophallus johnsonii (Araceae) by carrion beetles (Phaeochrous amplus) in a Ghanaian rain forest

1996 ◽  
Vol 12 (3) ◽  
pp. 409-418 ◽  
Author(s):  
Daniel D. N. Beath
Keyword(s):  
Rain Forest ◽  
Rainy Season ◽  
Male Inflorescence ◽  
Large Numbers ◽  
Female Phase ◽  
Male Phase ◽  
Carrion Beetles ◽  
Main Rainy Season

ABSTRACTAmorphophallus johnsonii (N. E. Brown) flowers during April in the main rainy season in Ghana. Anthesis starts at dusk with fluid oozing from the upper spadix accompanied by a strong aminoid odour. Just after dark large numbers of carrion beetles (Phaeochrous amplus) and occasional dung fly species (Hemigymnochaeta unicolor and Paryphodes tigrinus) visit the inflorescences. The beetles become trapped in the lower spathe overnight and remain in the spadix until the following evening. Between 1630 and 1645 h the following day, the anthers produce long threads of sticky pollen. The trapped beetles escape just after dark by crawling up the spadix, past the dehisced anthers and fly away from the spadix tip. Marked beetles were seen to transfer pollen from male phase to female phase inflorescences. Successful fertilisation was only effected if pollen was transferred on the same night from a male inflorescence 30 m or less away. Pollen is psilate and typical of beetle pollinated Araceae. Berries ripen approximately 70 d after fertilization and ripen basisetally in the infructescence.

scholarly journals Male flowers of Aconitum compensate for toxic pollen with increased floral signals and rewards for pollinators

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
A.-L. Jacquemart ◽  
C. Buyens ◽  
M.-F. Hérent ◽  
J. Quetin-Leclercq ◽  
G. Lognay ◽  
...  
Keyword(s):  
Larval Food ◽  
Chemical Defences ◽  
Toxic Nectar ◽  
Pollen Transfer Efficiency ◽  
Aconitum Napellus ◽  
Female Phase ◽  
Male Phase ◽  
Male Flowers ◽  
Nectar Rewards ◽  
Toxic Pollen

Abstract Many plants require animal pollinators for successful reproduction; these plants provide pollinator resources in pollen and nectar (rewards) and attract pollinators by specific cues (signals). In a seeming contradiction, some plants produce toxins such as alkaloids in their pollen and nectar, protecting their resources from ineffective pollinators. We investigated signals and rewards in the toxic, protandrous bee-pollinated plant Aconitum napellus, hypothesizing that male-phase flower reproductive success is pollinator-limited, which should favour higher levels of signals (odours) and rewards (nectar and pollen) compared with female-phase flowers. Furthermore, we expected insect visitors to forage only for nectar, due to the toxicity of pollen. We demonstrated that male-phase flowers emitted more volatile molecules and produced higher volumes of nectar than female-phase flowers. Alkaloids in pollen functioned as chemical defences, and were more diverse and more concentrated compared to the alkaloids in nectar. Visitors actively collected little pollen for larval food but consumed more of the less-toxic nectar. Toxic pollen remaining on the bee bodies promoted pollen transfer efficiency, facilitating pollination.

scholarly journals Linking pollinator efficiency to patterns of pollen limitation: small bees exploit the plant–pollinator mutualism

2018 ◽  
Vol 285 (1880) ◽  
pp. 20180635 ◽  
Author(s):  
Matthew H. Koski ◽  
Jennifer L. Ison ◽  
Ashley Padilla ◽  
Angela Q. Pham ◽  
Laura F. Galloway
Keyword(s):  
Pollen Limitation ◽  
Pollen Deposition ◽  
Pollinator Efficiency ◽  
Flower Visitation ◽  
Female Phase ◽  
Male Phase ◽  
Single Flower ◽  
Floral Visitation ◽  
Low Efficiency ◽  
Plant Pollinator

Seemingly mutualistic relationships can be exploited, in some cases reducing fitness of the exploited species. In plants, the insufficient receipt of pollen limits reproduction. While infrequent pollination commonly underlies pollen limitation (PL), frequent interactions with low-efficiency, exploitative pollinators may also cause PL. In the widespread protandrous herb Campanula americana , visitation by three pollinators explained 63% of the variation in PL among populations spanning the range. Bumblebees and the medium-sized Megachile campanulae enhanced reproductive success, but small solitary bees exacerbated PL. To dissect mechanisms behind these relationships, we scored sex-specific floral visitation, and the contributions of each pollinator to plant fitness using single flower visits. Small bees and M. campanulae overvisited male-phase flowers, but bumblebees frequently visited female-phase flowers. Fewer bumblebee visits were required to saturate seed set compared to other bees. Scaling pollinator efficiency metrics to populations, small bees deplete large amounts of pollen due to highly male-biased flower visitation and infrequent pollen deposition. Thus, small bees reduce plant reproduction by limiting pollen available for transfer by efficient pollinators, and appear to exploit the plant–pollinator mutualism, acting as functional parasites to C. americana . It is therefore unlikely that small bees will compensate for reproductive failure in C. americana when bumblebees are scarce.

scholarly journals Comparing Pre- and Post-pollen Production Temperature Stress on Fruit Set and Fruit Production In Male-sterile And Male-fertile Tomatoes

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 526C-526
Author(s):  
Mary M. Peet ◽  
Suguru Sato
Keyword(s):  
Temperature Stress ◽  
Fruit Set ◽  
Fruit Production ◽  
Fruit Yield ◽  
Effect Of Temperature ◽  
Pollen Production ◽  
Night Temperature ◽  
Male Sterile ◽  
Male And Female ◽  
Reproductive Tissues

Peet et al. (1997) demonstrated that in male-sterile tomato plants (Lycopersicon esculentum L. Mill cv. NC8288) (MSs) provided with pollen from male-fertile plants (MFs) grown at 24°C daily mean, percent fruit set, total number and weight of fruit, and relative seediness decreased linearly as mean daily temperature rose from 25 to 29°C. The primary parameter affecting these variables was mean temperature, with day temperature at a given night temperature, night temperature at a given day temperature, and day/night temperature differential having secondary or no effect. To compare the effect of temperature stress experienced only by the female tissues with that experienced by the male tissues or both male and female tissues, MSs and MFs were grown in 28/22°C, 30/24°C, and 32/26°C day/night temperature chambers. Fruit yield and seed number per fruit declined sharply when increased temperatures were experienced by both male and female tissues (MFs). There was no fruit set in any of the MSs assigned to the 32/26°C pollen treatment, mostly because of the limited amount of pollen available from MFs. Both fruit production and seed content per fruit were also greatly reduced in MSs receiving pollen from 30/24°C grown MFs for the same reason. For plants experiencing stress only on female tissues (MSs grown at high temperatures, but receiving pollen from MFs grown at the lowest temperature), there was also a linear decrease in fruit yield as growth temperatures increased, as previously seen by Peet et al. (1997), but the temperature effect was less pronounced than that on pollen production. Thus, for this system, temperature stress decreased yield much more drastically when experienced by male reproductive tissues than when experienced only by female reproductive tissues.

Within and among flower sex-phase distribution in Alstroemeria aurea (Alstroemeriaceae)

1995 ◽  
Vol 73 (12) ◽  
pp. 1986-1994 ◽  
Author(s):  
Marcelo A. Aizen ◽  
Alicia Basilio
Keyword(s):  
Inbreeding Depression ◽  
Seed Set ◽  
Phase Distribution ◽  
Selfing Rate ◽  
Pollen Transfer ◽  
Alstroemeria Aurea ◽  
Female Phase ◽  
Male Phase ◽  
Male To Female ◽  
Simultaneous Change

Although dichogamy is a prevailing feature of the angiosperms, the simultaneous change from male to female phases among hermaphrodite flowers within a plant (i.e., synchronous protandry) has been reported for only a few families (e.g., Araliaceae, Umbelliferae). Here we present an example of synchronous protandry at the ramet level in the Alstroemeriaceae. Dichogamy was analyzed in clonal Alstroemeria aurea at the flower, ramet, and at the whole flowering patch level. Alstroemeria aurea is self-compatible but totally dependent on biotic agents for pollen transfer. There was evidence of strong inbreeding depression expressed during seed development. Comparisons of seed set in open-pollinated flowers with those obtained after hand selfing and outcrossing resulted in a selfing rate of 0.3. At the flower level protandry was complete. The male phase lasted about 4 days and the female phase lasted about 3 days. Between the female and male phase, there was an approximately 1-day long "neuter" phase. Flowering ramets produce a terminal inflorescence bearing one or more whorls of flowers. Within a ramet, flowers of the same order opened within a period of 1–2 days, and male and female phases of different flowers did not overlap. When inflorescences held two whorls of flowers, the ramet went through two alternating non-overlapping male–female cycles. Using spatial autocorrelation techniques, we found little evidence for pairs of neighboring ramets expressing the same sexual phase beyond random expectations at any scale ranging between 0.25 to 15 m. By ensuring pollen interchange between flowering ramets, synchronized protandry at the ramet level could be an important feature in reducing selfing in A. aurea. Key words: Alstroemeria aurea, dichogamy, synchronous protandry, inbreeding depression.

Primary Sex-Phases in Ostrea Edulis

1942 ◽  
Vol s2-83 (331) ◽  
pp. 317-356
Author(s):  
H. A. COLE
Keyword(s):  
Water Temperature ◽  
Environmental Conditions ◽  
Initial Phase ◽  
Gonad Development ◽  
Ostrea Edulis ◽  
Male Condition ◽  
Female Phase ◽  
Male Phase ◽  
One Year ◽  
Transitional Phase

1. It is only under the most favourable conditions that oysters (Ostrea edulis) mature in the first sexual phase in the same season as that in which they attach themselves. During this initial phase the oyster functions as a male. 2. Normally the first male phase is experienced on British beds in the summer following that in which the oyster attaches itself and is rapidly followed by the first female phase, the oocytes developing on the walls of the follicles while spermatogenesis proceeds in the lumina. 3. In favourable seasons about a third of a population of one-year-old oysters will spawn as females. In unfavourable years only a few of the heaviest oysters spawn. Following female spawning the second male phase is rapidly assumed. 4. The second male phase is followed by the second female phase, the oocytes developing while spermatogenesis is in progress. Emission of sperm may be continued up to within a few days of egg-spawning. If a male phase is reached towards the close of the season it is followed by a resting phase, without spermatogenesis or large oocytes in the gonad, which persists throughout the winter. Similar resting phases may occur during the summer if environmental conditions are unfavourable. 5. Every two-year-old oyster functions as a female in a favourable season, and thereafter under normal conditions passes through at least two sex-phases each season, functioning both as a male and as a female. Evidence is adduced to show that in populations of adult oysters on British beds 100 per cent, female functioning occurs in favourable seasons. 6. Gonad development is arrested from approximately the end of October until the beginning of April while the water temperature is below about 10°C. Oysters may winter in almost any sex-phase, but spermatogenesis does not occur, although ripe sperm morulae may be carried over from one season to the next. Egg development is arrested during the winter months. 7. Oysters which winter in a transitional phase between a male and a female phase may mature as pure females early in the following summer without any recrudescence of spermatogenesis. There is at this time, therefore, a high proportion of ripe females in the population. 8. Oysters which winter in a dormant male condition mature as good males early in the following season and spawn as females later in the summer. Female spawners may therefore be divided roughly into two groups--early and late spawners--and individual oysters tend to remain in the same group in successive years. 9. Breakdown and absorption of large eggs by phagocytes has been found to occur occasionally during the winter, but the circumstances in which this takes place are not known.

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