Rapport des sexes, effort et succès de reproduction chez Rubus chamaemorus, plante herbacée vivace dioïque de distribution subarctique

1987 ◽  
Vol 65 (12) ◽  
pp. 2628-2639 ◽  
Author(s):  
Pascale Dumas ◽  
Lucie Maillette
Keyword(s):  
Reproductive Success ◽  
Sexual Reproduction ◽  
Sex Ratios ◽  
Female Flower ◽  
Fruit Production ◽  
Climatic Conditions ◽  
Total Biomass ◽  
Dioecious Species ◽  
Pollinator Behaviour ◽  
Rubus Chamaemorus

Studies published on the reproductive success of dioecious species concentrate on the role of sex ratios and pollinator behaviour. In the case of Rubus chamaemorus L., a circumboreal dioecious species, we hypothesized that flower survival and biomass allocation to reproductive tissues, which are climate dependent, also influence fruit production. Only 0.05% of total biomass is allocated to reproduction, whereas 94% goes to underground organs responsible for vegetative propagation. Many male (28 – 51%) and female flower buds (35 – 54%) and young fruits (24–51%) die prematurely mainly because of the climate; fruit production then becomes independent from initial female flower density. The scarcity of female flowers at most sites (except near open water) limits fruit production. The limited sexual reproduction would allow cloudberry to maintain somatic resources, thereby increasing the longevity of individuals and their chance of encountering the climatic conditions required for reproductive success. Such a strategy is adaptive in a variable climate like that of the subarctic. Furthermore, the reduced importance of sexual reproduction would diminish the need to optimize sex ratios. Other selective pressures (e.g., competition) would then favour male clones in most sites, in spite of the unproductive pollen excess.

scholarly journals Mating system and female reproductive success of the endemic, epiphytic Prosthechea aff. karwinskii (Orchidaceae)

Lankesteriana ◽  
2011 ◽  
Vol 11 (3) ◽  
Author(s):  
Ericka Camacho-Domínguez ◽  
Irene Ávila-Díaz
Keyword(s):  
Reproductive Success ◽  
Mating System ◽  
Sexual Reproduction ◽  
Fruit Set ◽  
Natural Populations ◽  
Fruit Production ◽  
Open Pollination ◽  
Female Reproductive Success ◽  
Hand Pollination ◽  
Northern Portion

Prosthechea aff. karwinskii (Mart.) Soto Arenas & Salazar (unpublished name) is an endemic Mexican epiphytic orchid with a restricted distribution. It occurs in deciduous oak forests, particularly on Quercus deserticola in the northern portion of Michoacán state. Due to their ornamental uses, this and other orchid species have been heavily collected from their natural populations. Learning about the reproductive biology of this species is important, as we may gain knowledge about the probable repercussions of overcollecting on their genetics and ecology. This will be a useful tool for the management and conservation of the species. The objectives were to 1) study the mating system of P. aff. karwinskii, 2) determine if the species requires an external pollinating agent for sexual reproduction, and 3) evaluate female reproductive success of this species. Exclusions (150) were made before anthesis. Once the flowers opened, we applied four pollination treatments: manual selfing, outcrossing, spontaneous autogamy, and open pollination. We subsequently quantified the production of fruits and viability of the seeds. Preliminary results showed that outcrossing and selfing treatments exhibited statistically higher fruit set than spontaneous autogamy and open pollination treatments, meaning that P. aff. karwinskii has the capability to reproduce via self-pollination. Prosthechea aff. karwinskii is pollinator-dependent for sexual reproduction, taking into account that the spontaneous autogamy treatment showed nil fruit production. Female reproductive success in open pollinated flowers was lower compared to fruit set of hand pollination treatments. This indicates that this species, as other species of tropical orchids, is pollination-limited. 

scholarly journals Orchard layout and plant traits influence fruit yield more strongly than pollinator behaviour and density in a dioecious crop

2020 ◽  
Author(s):  
Angela Peace ◽  
David Pattermore ◽  
Melissa Broussard ◽  
Dilini Fonseka ◽  
Nathan Tomer ◽  
...  
Keyword(s):  
Management Practices ◽  
Plant Traits ◽  
Latin Hypercube Sampling ◽  
Female Flower ◽  
Fruit Production ◽  
Fruit Yield ◽  
Production Plant ◽  
Pollinator Behaviour ◽  
Pollination Success ◽  
Plant Pollinator

AbstractMutualistic plant-pollinator interactions are critical for the functioning of both non-managed and agricultural systems. Mathematical models of plant-pollinator interactions can help understand key determinants in pollination success. However, most previous models have not addressed pollinator behavior and plant biology combined. Information generated from such a model can inform optimal design of crop orchards and effective utilization of managed pollinators like honey bees, and help generate hypotheses about the effects of management practices and cultivar selection. We expect that honey bee density per flower and male to female flower ratio will influence fruit yield. To test the relative importance of these effects, both singly and simultaneously, we utilized a delay differential equation model combined with Latin hypercube sampling for sensitivity analysis. Empirical data obtained from historical records and collected in kiwifruit orchards in New Zealand were used to parameterize the model. We found that, at realistic bee densities, the optimal orchard had 65-75% female flowers, and the most benefit was gained from the first 6-8 bees/1000 flowers, with diminishing returns thereafter. While bee density significantly impacted fruit production, plant-based parameters-flower density and male:female flower ratio-were the most influential. The predictive model provides strategies for improving crop management.

Sex ratio, flowering and fruit set in dioecious Rubus chamaemorus (Rosaceae) in Labrador

Botany ◽  
2008 ◽  
Vol 86 (2) ◽  
pp. 204-212 ◽  
Author(s):  
Amanda L. Karst ◽  
Joseph A. Antos ◽  
Geraldine A. Allen
Keyword(s):  
Sex Ratio ◽  
Fruit Set ◽  
Seed Set ◽  
Sex Ratios ◽  
Fruit Production ◽  
Habitat Characteristics ◽  
Rubus Chamaemorus ◽  
Males And Females ◽  
Unpredictable Environment ◽  
Female Flowers

Rubus chamaemorus L. is a dioecious clonal herb with highly variable fruit production. Our overall objective was to determine how fruit production (and the reproductive stages leading to fruit) for R. chamaemorus varied with habitat and population (especially sex ratio) characteristics at scales from 1 m2 quadrats to whole populations in southeastern Labrador, Canada. During the climatically favourable year studied, reproductive variables were only weakly correlated with habitat characteristics. Strongly biased sex ratios were found at scales of 1–10 m. Male-dominated quadrats exhibited a significantly higher proportion of flowering ramets than did female-dominated quadrats. Female-biased sex ratios of flowering ramets and large distances between male and female flowers were correlated with decreased seed set. We found no differences in microhabitats of males and females. Although the biased local sex ratios could limit sexual reproduction, the high fruit set we measured clearly indicates that populations are able to produce abundant fruit during favourable years in this unpredictable environment.

scholarly journals A comparative study on the reproductive success of two rewarding Habenaria species (Orchidaceae) occurring in roadside verge habitats

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wenliu Zhang ◽  
Jiangyun Gao
Keyword(s):  
Reproductive Success ◽  
Fruit Set ◽  
Plant Density ◽  
Flowering Plant ◽  
Floral Display ◽  
Pollinator Behaviour ◽  
Factors Affecting ◽  
Nectar Sugar ◽  
Viable Seeds ◽  
Viable Embryo

Abstract Background Most orchid species have been shown to be severely pollination limited, and the factors affecting reproductive success have been widely studied. However, the factors determining the reproductive success vary from species to species. Habenaria species typically produce nectar but exhibit variable fruit set and reproductive success among species. Here, we investigated the influence of the flowering plant density, inflorescence size, breeding system, and pollinator behaviour on the reproductive success of two rewarding Habenaria species. Results Our observations indicated that Habenaria limprichtii and H. petelotii co-occur in roadside verge habitats and present overlapping flowering periods. Both species were pollination limited, although H. limprichtii produced more fruits than H. petelotii under natural conditions during the 3-year investigation. H. petelotii individuals formed distinct patches along roadsides, while nearly all H. limprichtii individuals clustered together. The bigger floral display and higher nectar sugar concentration in H. limprichtii resulted in increased attraction and visits from pollinators. Three species of effective moths pollinated for H. limprichtii, while Thinopteryx delectans (Geometridae) was the exclusive pollinator of H. petelotii. The percentage of viable seeds was significantly lower for hand geitonogamy than for hand cross-pollination in both species. However, H. limprichtii may often be geitonogamously pollinated based on the behaviours of the pollinators and viable embryo assessment. Conclusions In anthropogenic interference habitats, the behaviours and abundance of pollinators influence the fruit set of the two studied species. The different pollinator assemblages in H. limprichtii can alleviate pollinator specificity and ensure reproductive success, whereas the more viable embryos of natural fruit seeds in H. petelotii suggested reducing geitonogamy by pollinators in the field. Our results indicate that a quantity-quality trade-off must occur between species with different breeding strategies so that they can fully exploit the existing given resources.

scholarly journals Inconclusive evidence of sexual reproduction of invasive Halophila stipulacea: a new field guide to encourage investigation of flower and fruit production throughout its invasive range

2020 ◽  
Vol 63 (6) ◽  
pp. 537-540
Author(s):  
Fee O.H. Smulders ◽  
Kelcie L. Chiquillo ◽  
Demian A. Willette ◽  
Paul H. Barber ◽  
Marjolijn J.A. Christianen
Keyword(s):  
Sexual Reproduction ◽  
Clonal Growth ◽  
Large Scale ◽  
Fruit Production ◽  
Morphological Evidence ◽  
Invasive Range ◽  
Reproductive Structures ◽  
Halophila Stipulacea ◽  
The Caribbean ◽  
Low Rate

AbstractThe dioecious seagrass species Halophila stipulacea reproduces mainly through fast clonal growth, underlying its invasive behavior. Here, we provide morphological evidence to show that the first findings of fruits in the Caribbean were misidentified. Consequently, H. stipulacea reproduction is likely still only asexual in the Caribbean. Therefore, we introduce an identification key of H. stipulacea reproductive structures to encourage careful identification and quantification throughout its invasive range. Until large-scale seed production in invaded habitats is reported, the apparent low rate of sexual reproduction needs to be considered in current studies investigating the invasion capacity of this species.

scholarly journals Reproductive biology of Macleania rupestris (Ericaceae), a pollen-limited Neotropical cloud-forest species in Costa Rica

2010 ◽  
Vol 26 (3) ◽  
pp. 351-354 ◽  
Author(s):  
Eric J. Fuchs ◽  
Jeffrey Ross-Ibarra ◽  
Gilbert Barrantes
Keyword(s):  
Costa Rica ◽  
Relative Humidity ◽  
Reproductive Success ◽  
Cloud Forest ◽  
Fruit Production ◽  
Foraging Activity ◽  
High Altitudes ◽  
Forest Species ◽  
Effective Time ◽  
Complex Interactions

The reproductive success of hummingbird-pollinated plants often depends on complex interactions between environmental conditions and pollinator biology (Navarro 1999, Stiles 1985, Wolf et al. 1976). The effect of environment on reproductive success of hummingbird-pollinated plants is particularly pronounced at high altitudes, where large daily fluctuations in temperature, relative humidity and solar radiation limit the effective time for photosynthesis (Cavieres et al. 2000) and affect foraging activity (Navarro 1999) and abundance of pollinators (Rahbek 1997). At high altitudes in the tropical cloud forests of Costa Rica these factors may have serious impacts on fruit production.

Reproductive success of wind, generalist, and specialist pollinated plant species following wildfire in desert landscapes

2017 ◽  
Vol 26 (12) ◽  
pp. 1030 ◽  
Author(s):  
Andrew H. Lybbert ◽  
Justin Taylor ◽  
Alysa DeFranco ◽  
Samuel B. St Clair
Keyword(s):  
Reproductive Success ◽  
Plant Species ◽  
Mojave Desert ◽  
Fruit Production ◽  
Native Plant ◽  
Pollination Services ◽  
Generalist Species ◽  
Plant Reproductive Success ◽  
Show Evidence ◽  
Specialist Species

Wildfire can drastically affect plant sexual reproductive success in plant–pollinator systems. We assessed plant reproductive success of wind, generalist and specialist pollinated plant species along paired unburned, burned-edge and burned-interior locations of large wildfires in the Mojave Desert. Flower production of wind and generalist pollinated plants was greater in burned landscapes than adjacent unburned areas, whereas specialist species responses were more neutral. Fruit production of generalist species was greater in burned landscapes than in unburned areas, whereas fruit production of wind- and specialist-pollinated species showed no difference in burned and unburned landscapes. Plants surviving in wildfire-disturbed landscapes did not show evidence of pollination failure, as measured by fruit set and seed:ovule ratios. Generalist- and specialist-plant species established in the interior of burned landscapes showed no difference in fruit production than plants established on burned edges suggesting that pollination services are conserved with increasing distance from fire boundaries in burned desert landscapes. Stimulation of plant reproduction in burned environments due to competition release may contribute to the maintenance of pollinator services and re-establishment of the native plant community in post-fire desert environments.

Pollination by deceit, floral sex ratios and seed set in dioecious Rubus chamaemorus L.

Oecologia ◽  
1986 ◽  
Vol 70 (3) ◽  
pp. 332-338 ◽  
Author(s):  
J. Ågren ◽  
T. Elmqvist ◽  
A. Tunlid
Keyword(s):  
Seed Set ◽  
Sex Ratios ◽  
Rubus Chamaemorus

Cryptic dioecy in Actinidia polygama: a test of the pollinator attraction hypothesis

2004 ◽  
Vol 82 (2) ◽  
pp. 214-218 ◽  
Author(s):  
Tetsuhiro Kawagoe ◽  
Nobuhiko Suzuki
Keyword(s):  
Fruit Production ◽  
Sexual System ◽  
Dioecious Species ◽  
Pollinator Attraction ◽  
Cryptic Dioecy ◽  
Actinidia Polygama ◽  
Unisexual Flowers ◽  
Sterile Pollen ◽  
Female Flowers

Female flowers of some dioecious species are known to develop stamens with sterile pollen, a sexual system known as cryptic dioecy. A convincing hypothesis explaining this phenomenon is that stamens in female flowers attract pollinators and so ensure seed production. However, because this hypothesis has rarely been tested experimentally, we tested it in a cryptically dioecious species, Actinidia polygama (Sieb. et Zucc.) Planch. ex Maxim. Our findings show that pollinators do not show a consistent preference based on the sex of the flowers, and that the removal of stamens from female flowers results in a significant reduction in the frequency of insect visits and fruit production. These results strongly support the pollinator attraction hypothesis in A. polygama. Given the evident role of stamens in female flowers in A. polygama reproduction, we discuss why cryptic dioecy is a rare phenomenon.Key words: Actinidia polygama, cryptic dioecy, pseudopollen, pollinator attraction, unisexual flowers.

Translocation heterozygosity in southern African species of Viscum

Bothalia ◽  
1980 ◽  
Vol 13 (1/2) ◽  
pp. 161-169 ◽  
Author(s):  
D. Wiens ◽  
B. A. Barlow
Keyword(s):  
Sex Ratios ◽  
Meiotic Drive ◽  
Sex Factors ◽  
Structural Rearrangements ◽  
Dioecious Species ◽  
African Species ◽  
High Frequencies ◽  
Supernumerary Chromosomes ◽  
Adaptive Value ◽  
Translocation Heterozygosity

Sex-associated and floating translocation complexes are characteristic of dioecious species of  Viscum,  but are virtually absent in monoecious species. The majority of dioecious species has fixed sex-associated translocation complexes with the male being the heterozygous sex. The sex-associated multivalent is usually O4 (ring-of-four) or O6 , rarely O8 . Dioecious species without sex-associated translocations are much less common. Most of the dioecious species are also polymorphic for floating translocations, producing one or more additional multivalents ranging from O4 to O12. Floating translocations may be more frequent in species that do not have sex-associated translocations. Supernumerary chromosomes are also present in several species. Sex ratios are at unity in most dioecious species, but female-biased ratios may occur in some species. The high correlation between dioecy and translocation heterozygosity suggests that translocations are primarily associated with the origin and establishment of dioecy. Any róle in the maintenance of biased sex ratios through meiotic drive is probably secondary. Sex-associated translocations may serve to stabilize dioecy by bringing the sex factors into close linkage. Subsequent structural rearrangements within a sex-associated translocation complex may bring the sex factors together in one chromosome pair, releasing floating translocations. The high frequencies of floating translocation heterozygosity in some species indicate that such heterozygosity also has adaptive value.

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