Measurements of Selection in a Hermaphroditic Plant: Variation in Male and Female Pollination Success

Evolution ◽  
1989 ◽  
Vol 43 (2) ◽  
pp. 318 ◽  
Author(s):  
Diane R. Campbell
Keyword(s):  
Plant Variation ◽  
Male And Female ◽  
Pollination Success ◽  
Hermaphroditic Plant

scholarly journals Sexual ratio and floral biology of the dioecious Neea theifera Oerst. (Nyctaginaceae) in a cerrado rupestre of central Brazil

2011 ◽  
Vol 25 (4) ◽  
pp. 785-792 ◽  
Author(s):  
Felipe Wanderley Amorim ◽  
Clesnan Mendes-Rodrigues ◽  
Pietro Kiyoshi Maruyama ◽  
Paulo Eugênio Oliveira
Keyword(s):  
Resource Allocation ◽  
Sex Ratio ◽  
Reproductive Biology ◽  
Reproductive Strategy ◽  
Pollen Viability ◽  
Floral Biology ◽  
Pollinator Limitation ◽  
Dioecious Species ◽  
Male And Female ◽  
Pollination Success

Dioecy is characterized by a complete separation of sexual functions on male and female plants. It has evolved many times in flowering plants and is widespread among distinct Angiosperm families. It is viewed as a reproductive strategy to reduce endogamy, and to promote optimal resource allocation between male and female sexual functions. Neea theifera is a common species in Cerrado, neotropical savannas in Brazil, but information regarding its reproductive biology is still incomplete. In order to investigate how environmental conditions possibly affect this dioecious species, we studied its floral biology, sex ratio and spatial distribution of sexual morphs along a soil-altitudinal gradient. The sex ratio did not significantly deviate from the expected 1:1 ratio. However, flower abundance in the population was significantly biased towards staminate flowers. Female individuals were larger than male individuals and plant size was negatively correlated with altitude, but did not differ between sexual morphs. The population did not show spatial segregation of sexes and male individuals were sexually mature earlier than female ones. Staminate flowers were larger than pistillate flowers and presented high pollen viability. Meliponini bees, small flies and thrips were potential pollinators, but pollination success was very low. Dioecy in N. theifera corroborates many general features of this reproductive strategy, such as woody habit, inconspicuous flowers, pollination by small generalist insects and differential resource allocation between male and female plants. However, reproduction in this species seems to be impaired by pollinator limitation. The results showed that the soil-altitude gradient influenced the growth pattern of the species and may play an important role in its reproductive biology but did not affect dioecy directly.

Effect of nectar supplementation on male and female components of pollination success in the deceptive orchid Dactylorhiza sambucina

2008 ◽  
Vol 33 (3) ◽  
pp. 300-306 ◽  
Author(s):  
Jana Jersáková ◽  
Steven D. Johnson ◽  
Pavel Kindlmann ◽  
Anne-Charlotte Pupin
Keyword(s):  
Male And Female ◽  
Pollination Success ◽  
Dactylorhiza Sambucina

Male and Female Pollination Success in a Deceptive Orchid, a Selection Study

Ecology ◽  
1998 ◽  
Vol 79 (4) ◽  
pp. 1246 ◽  
Author(s):  
Lisa M. O'Connell ◽  
Mark O. Johnston
Keyword(s):  
Male And Female ◽  
Pollination Success

Uneven ploidy levels and a reproductive mutant required for interspecific hybridization of Medicago sativa L. × Medicago dzhawakhetica Bordz.

1984 ◽  
Vol 26 (5) ◽  
pp. 511-518 ◽  
Author(s):  
T. J. McCoy ◽  
L. Y. Smith
Keyword(s):  
Medicago Sativa ◽  
Interspecific Hybrids ◽  
Backcross Progeny ◽  
Male Sterile ◽  
Plant Variation ◽  
Ploidy Levels ◽  
Male And Female ◽  
Large Numbers ◽  
Medicago Sativa L ◽  
Efficient Recovery

Crossing diploid (2n = 2x = 16) Medicago sativa L. (homozygous for the gene, jp, that causes failure of the postmeiotic cytokinesis) and tetraploid (2n = 4x = 32) Medicago dzhawakhetica Bordz. resulted in efficient recovery of interspecific hybrids. Interspecific hybrids were produced in large numbers (1.15 – 5.60 hybrids per pollination), comparable to intraspecific same-ploidy level crosses within M. sativa. All 237 interspecific hybrids were triploid (2n = 3x = 24) or near triploid. Morphologically, the F1 hybrids were intermediate, although they tended to be more similar to the M. dzhawakhetica parent. Medicago dzhawakhetica was resistant to spring blackstem (caused by Phoma medicaginis Malb. and Roum.), whereas the M. sativa parents were susceptible. The F1 hybrids were also resistant to P. medicaginis. Chromosome pairing in the hybrids showed plant-to-plant variation; however, trivalent frequencies in some F1 hybrids were comparable to that observed in M. sativa triploids, indicating potential for recombination between M. sativa and M. dzhawakhetica genomes. Although the triploid hybrids were male sterile, and nearly female sterile, it was possible to produce backcross progeny. The first backcross was both male and female fertile.Key words: Medicago, hybridization, breeding, tetraploid, triploid, sterility.

FORAGING BEHAVIOUR OF HONEY BEES (APIS MELLIFERA L.) ON STAGHORN SUMAC [RHUS HIRTA SUDWORTH (EX-TYPHINA L.)]: DIFFERENCES AND DIOECY

1996 ◽  
Vol 128 (3) ◽  
pp. 355-366 ◽  
Author(s):  
Carlos F. Greco ◽  
Dean Holland ◽  
Peter G. Kevan
Keyword(s):  
Apis Mellifera ◽  
Reproductive Success ◽  
Honey Bees ◽  
Foraging Behaviour ◽  
Anther Dehiscence ◽  
Male And Female ◽  
Pollination Success ◽  
Pollen Loads ◽  
Natural Stands ◽  
Foraging Pattern

AbstractThe foraging behaviour of honey bees (Apis mellifera L.) on inflorescences of staghorn sumac [Rhus hirta Sudworth (ex-typhina L.)] was studied using a “choice table” placed in natural stands of this plant. The choice table consisted of a wooden grid with alternated male and female inflorescences of sumac. Honey bee activity was recorded also on inflorescences of naturally growing plants in which the secretion of nectar was measured and the anther dehiscence recorded. Honey bees were the only common pollinators observed on sumac in the study area. During the morning, both plant sexes secreted little nectar, and pollen was available after the dehiscence of the anthers which took place between 1000 and 1100 hours. Female inflorescences secreted great amounts of nectar during the afternoon, but in male inflorescences there was little secretion. Honey bees seemed to forage according to the circadian availability of resources. Most of their activity concentrated on male inflorescences in the morning and on female ones during the afternoon. Both the occurrence of bees with pollen loads in their corbiculae and the length of the visits to each sex also seemed to be in accordance to the kind of resource exploited at particular times of the day. Most of the bees with pollen loads were observed during the morning and the longest visits to any inflorescences were registered on female ones during the afternoon (by bees foraging for nectar). Despite our results suggesting that the pollination success of staghorn sumac would be impaired by the foraging pattern of honey bees, an explanation is proposed for its reproductive success.

MALE AND FEMALE POLLINATION SUCCESS IN A DECEPTIVE ORCHID, A SELECTION STUDY

Ecology ◽  
1998 ◽  
Vol 79 (4) ◽  
pp. 1246-1260 ◽  
Author(s):  
Lisa M. O’Connell ◽  
Mark O. Johnston
Keyword(s):  
Male And Female ◽  
Pollination Success

The Clinical, Roentgenological and Morphological Effects of an Acute Exposure of Phosgene on the Lungs of Dogs

1971 ◽  
Vol 29 ◽  
pp. 236-237
Author(s):  
R. F. Bils ◽  
W. F. Diller ◽  
F. Huth
Keyword(s):  
Latent Period ◽  
Chemical Industry ◽  
Toxic Substance ◽  
Lung Edema ◽  
X Rays ◽  
Beagle Dogs ◽  
Male And Female ◽  
Morphological Alterations ◽  
Before And After ◽  
Electron Microscopes

Phosgene still plays an important role as a toxic substance in the chemical industry. Thiess (1968) recently reported observations on numerous cases of phosgene poisoning. A serious difficulty in the clinical handling of phosgene poisoning cases is a relatively long latent period, up to 12 hours, with no obvious signs of severity. At about 12 hours heavy lung edema appears suddenly, however changes can be seen in routine X-rays taken after only a few hours' exposure (Diller et al., 1969). This study was undertaken to correlate these early changes seen by the roengenologist with morphological alterations in the lungs seen in the'light and electron microscopes.Forty-two adult male and female Beagle dogs were selected for these exposure experiments. Treated animals were exposed to 94.5-107-5 ppm phosgene for 10 min. in a 15 m3 chamber. Roentgenograms were made of the thorax of each animal before and after exposure, up to 24 hrs.

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