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.

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 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 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.

An Experiment on the Control of Tsetse (Glossina palpalis R.-D.) in High Forest of West Africa

1953 ◽  
Vol 44 (4) ◽  
pp. 703-710 ◽  
Author(s):  
B. J. A. Nowosielski-Slepowron
Keyword(s):  
Relative Humidity ◽  
West Africa ◽  
Rain Forest ◽  
Forest Type ◽  
Complete Eradication ◽  
Large Numbers ◽  
High Reduction ◽  
Trap Catches ◽  
The Town ◽  
Glossina Palpalis

Kumasi is a rapidly expanding township of about 80,000 inhabitants. This has led to an extensive building programme which has followed the ridges in the vicinity of the town, leaving the valleys in between potentially dangerous isolated habitats of Glossina. The danger from these isolated habitats is enhanced by the large numbers of itinerant labourers.The topography of the town and its surroundings is hilly; the vegetation is of semi-deciduous rain forest type, but with very thick secondary bush along most of the valleys in which the farms had been abandoned.The climate is remarkably equable with the rainfall showing periodicity but the percentage relative humidity is high and even throughout the year.The experimental clearing of an isolated habitat of Glossina in the Dechem valley was commenced in July 1950 and finished in March 1951. The clearing was of a discriminative nature, with cutting, stumping and burning of a strip of bush up to 20 ft. high and 250–300 yards wide along the stream, and a high reduction of fly population was achieved. This reduction was such that further clearings were planned.The reduction in fly population was assessed from fly-boy catches and from trap catches. These records showed that rainfall affected the catches.At the time of writing, about a sixth of the protective clearings planned around Kumasi have been completed, the fly population being reduced between about 80 per cent. and complete eradication.

scholarly journals The Gorongoza Reserve

Oryx ◽  
1971 ◽  
Vol 11 (2-3) ◽  
pp. 109-110 ◽  
Author(s):  
Archibald James
Keyword(s):  
Rainy Season ◽  
Large Numbers ◽  
The World ◽  
Game Reserve

The Gorongoza Game Reserve in Northern Mozambique is among the finest in the world, combining beauty of terrain with large numbers of birds and mammals in astonishing variety. About two miles from the camp is a flat treeless plain, some three miles across, flooded in the rainy season by the sluggish Pungwe river. Here some months ago I estimated well over 1000 animals of twelve species, with elephant, buffalo and wildebeest predominating, but strangely mixed.

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.

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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