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1.
《Plant Ecology & Diversity》2013,6(2-3):97-104
Background: The arrangement of flowers on inflorescences is important for determining the movement of pollinators within the inflorescence and, consequently, the overall mating success and fruit set of a plant.Aims: Spiranthes spiralis is an orchid that has a spiralled inflorescence. The species has two chiral forms that show opposite coiling directions (clockwise and anti-clockwise). We tested if this arrangement of inflorescence influences pollinator attraction and behaviour.Methods: We surveyed two natural populations, analysed the reproductive compatibility of the two morphs and estimated pollination success in natural and experimental populations.Results: We found that the two morphs were not isolated by pre- or post-mating barriers, occurred with a similar proportion in natural populations and showed similar levels of pollination success both in natural and artificial populations. However, we found a different pattern of pollination success along the inflorescences. In the two morphs, lower flowers experienced a higher pollination rate and this rate decreased along the inflorescence faster in anti-clockwise than in clockwise individuals.Conclusions: This finding suggests that pollinators visit the flowers sequentially from the lower part of the inflorescences and leave the anti-clockwise individuals more rapidly than the clockwise ones. However, this pollinator behaviour is not detrimental for the pollination success of either of the two morphs. 相似文献
2.
Effect of nectar-robbing birds on fruit set of Fuchsia magellanica in Tierra Del Fuego: a disrupted mutualism 总被引:3,自引:0,他引:3
1. This paper investigates spatial habitat variation in flower visitation by avian pollinators (mainly Hummingbirds) and nectar robbers to Fuchsia magellanica at the southern limit of its range, Tierra del Fuego, and their effects on plant reproductive success.
2. The plant-pollination mutualism appears to be disrupted as Hummingbirds ( Sephanoides galeritus) are rare at this high latitude and the frequencies of a nectar-robbing bird ( Phrygilus patagonicus) are high, especially in open areas where F. magellanica is most abundant.
3. Nectar robbery by P. patagonicus reduced fruit set about 20%, mainly because this fringillid can damage the ovary when piercing a flower. This bird was more abundant in open areas than inside the forest and, as expected, flower piercing was also more frequent in the former habitat.
4. Spatial variation was also found in the frequency of flower visitation by Hummingbirds; these birds foraged chiefly in the forest presumably because of the greater probability of finding intact (non-robbed) flowers there. This suggests that cross-pollinations in this self-compatible plant are more likely to occur in the forest. Nectar robbers therefore may influence not only the quantity of seeds produced but also, indirectly, their quality.
5. Fuchsia magellanica is polymorphic in flower colour. Robbery was significantly lower in the pale than in the normal (red) morph, although fruit set was similar between morphs. 相似文献
2. The plant-pollination mutualism appears to be disrupted as Hummingbirds ( Sephanoides galeritus) are rare at this high latitude and the frequencies of a nectar-robbing bird ( Phrygilus patagonicus) are high, especially in open areas where F. magellanica is most abundant.
3. Nectar robbery by P. patagonicus reduced fruit set about 20%, mainly because this fringillid can damage the ovary when piercing a flower. This bird was more abundant in open areas than inside the forest and, as expected, flower piercing was also more frequent in the former habitat.
4. Spatial variation was also found in the frequency of flower visitation by Hummingbirds; these birds foraged chiefly in the forest presumably because of the greater probability of finding intact (non-robbed) flowers there. This suggests that cross-pollinations in this self-compatible plant are more likely to occur in the forest. Nectar robbers therefore may influence not only the quantity of seeds produced but also, indirectly, their quality.
5. Fuchsia magellanica is polymorphic in flower colour. Robbery was significantly lower in the pale than in the normal (red) morph, although fruit set was similar between morphs. 相似文献
3.
S. Vandewoestijne A. S. Róis A. Caperta M. Baguette & D. Tyteca 《Plant biology (Stuttgart, Germany)》2009,11(3):454-463
Reproductive success (RS) in orchids in general, and in non-rewarding species specifically, is extremely low. RS is pollinator and pollination limited in food deceptive orchids, but this has rarely been studied in sexually deceptive orchid species. Here, we tested the effects of several individual (plant height, inflorescence size, nearest neighbour distance and flower position) and population (patch geometry, population density and size) parameters on RS in three sexually deceptive Ophrys (Orchidaceae) species. Inter-specific differences were observed in RS of flowers situated in the upper versus the lower part of the inflorescence, likely due to species-specific pollinator behaviour. For all three species examined, RS increased with increasing plant height, inflorescence size and nearest neighbour distance. RS generally increased with decreasing population density and increasing patch elongation. Given these results, we postulate that pollinator availability, rather than pollinator learning, is the most limiting factor in successful reproduction for sexually deceptive orchids. Our results also suggest that olfactory 'display' ( i.e. versus optical display), in terms of inflorescence size (and co-varying plant height), plays a key role in individual RS of sexually deceptive orchids. In this regard, several hypotheses are suggested and discussed. 相似文献
4.
Comparative pollination biology in two sympatric varieties of Cypripedium macranthos (Orchidaceae) on Rebun Island,Hokkaido, Japan
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Cypripedium macranthos sensu lato typically has purple‐pink flowers with no nectar and harvestable pollen. On Rebun Island, Hokkaido, Japan, purple‐pink‐flowered C. macranthos var. macranthos individuals rarely grow among numerous pale‐cream‐flowered C. macranthos var. rebunense plants. In both varieties, flower size is similar, their flowering periods completely overlap, and they share the same pollinator (Bombus pseudobaicalensis). However, in only one of 12 years from 2001 to 2012 did var. macranthos attain an annual fruit‐set ratio (an estimate of pollination success) higher than that of sympatric var. rebunense plants. These findings strongly suggest that in C. macranthos on Rebun Island, flower color results in the differential pollination success, because the pollinator prefers pale‐cream Cypripedium flowers and/or avoids purple‐pink ones, thereby producing pollinator‐mediated selection favoring pale‐cream flowers. 相似文献
5.
DAVID J. THOMPSON 《Ecological Entomology》1990,15(4):455-462
Abstract. 1. A simulation model is presented which describes, from field-estimated parameters, the effects of daily survival rate and proportion of sunny days on the lifetime egg production of females of the damselfly Coenagrion puella (L).
2. Lifetime egg production increases with daily survival rate and proportion of sunny days.
3. Estimates of mean lifetime egg production per female in bad and good summers in northern England ranged from 333 to 740.
4. The distribution, as well as the proportion, of sunny days influences lifetime egg production. For a given combination of daily survival and proportion of sunny days, lifetime egg production decreases as the distribution of sunny days becomes more clumped.
5. Lifetime egg production is largely determined by chance; females who begin their mature adult life during a period of sunny weather can produce many times more eggs than those whose mature adult life coincides with cloudy days. 相似文献
2. Lifetime egg production increases with daily survival rate and proportion of sunny days.
3. Estimates of mean lifetime egg production per female in bad and good summers in northern England ranged from 333 to 740.
4. The distribution, as well as the proportion, of sunny days influences lifetime egg production. For a given combination of daily survival and proportion of sunny days, lifetime egg production decreases as the distribution of sunny days becomes more clumped.
5. Lifetime egg production is largely determined by chance; females who begin their mature adult life during a period of sunny weather can produce many times more eggs than those whose mature adult life coincides with cloudy days. 相似文献
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7.
Age at first reproduction is an important component of lifehistory across taxa and can ultimately affect fitness. Becausegenetic interests of males and females over reproductive decisionscommonly differ, theory predicts that conflict may arise overthe temporal distribution of matings. To determine the potentialfor such sexual conflict, we studied the direct costs and benefitsassociated with mating at different times for females, usingseed beetles (Acanthoscelides obtectus) as a model system. Virginfemales were resistant to male mating attempts at a very earlyage but subsequently reduced their resistance. Although we foundno difference in life span or mortality rates between femalesmated early in life and those mated later, females that matedearly in life suffered a 12% reduction in lifetime fecundity.Thus, there are direct costs associated with mating early inlife for females. Yet, males mate even with newly hatched females.We suggest that these data indicate a potential for sexual conflictover the timing of first mating and that female resistance tomating, at least in part, may represent a female strategy aimedat delaying mating to a later time in life. 相似文献
8.
Interactive effects of environmental stress and inbreeding on reproductive traits in a wild bird population 总被引:3,自引:0,他引:3
1. Conservation biologists are concerned about the interactive effects of environmental stress and inbreeding because such interactions could affect the dynamics and extinction risk of small and isolated populations, but few studies have tested for these interactions in nature. 2. We used data from the long-term population study of song sparrows Melospiza melodia on Mandarte Island to examine the joint effects of inbreeding and environmental stress on four fitness traits that are known to be affected by the inbreeding level of adult birds: hatching success, laying date, male mating success and fledgling survival. 3. We found that inbreeding depression interacted with environmental stress to reduce hatching success in the nests of inbred females during periods of rain. 4. For laying date, we found equivocal support for an interaction between parental inbreeding and environmental stress. In this case, however, inbred females experienced less inbreeding depression in more stressful, cooler years. 5. For two other traits, we found no evidence that the strength of inbreeding depression varied with environmental stress. First, mated males fathered fewer nests per season if inbred or if the ratio of males to females in the population was high, but inbreeding depression did not depend on sex ratio. Second, fledglings survived poorly during rainy periods and if their father was inbred, but the effects of paternal inbreeding and rain did not interact. 6. Thus, even for a single species, interactions between the inbreeding level and environmental stress may not occur in all traits affected by inbreeding depression, and interactions that do occur will not always act synergistically to further decrease fitness. 相似文献