Similar Numbers Of Flowers Research Articles

Genetic relatedness and morphology as drivers of interspecific dominance hierarchy in hummingbirds.

A dominance hierarchy is the set of ranks occupied by species within an assemblage. Species with a high position within the dominance hierarchy tend to dominate subordinate species in contests for access to resources. In hummingbirds, greater weight and wing disc loading have been associated with highest ranks within the dominance hierarchy. Nevertheless, the limit to which the difference between the weight of contending species represents a competitive advantage has not yet been determined. Here, we determined the dominance hierarchy of a hummingbird assemblage exploiting the most abundant floral resource (Palicourea padifolia, Rubiaceae) in a cloud forest of central Veracruz, Mexico. Specifically, we tested whether species weight and wing disc loading influence the dominance hierarchy. Additionally, we tested whether the flowers visited per foraging bout increases with species weight and dominance. We further tested whether weight, wing disc loading, and the genetic relatedness between contenders influenced the dominance relationships in species-pair interactions. Our results indicate that the hierarchy is positively influenced by weight. Hummingbirds visited similar number of flowers regardless their weight or their dominance. Nevertheless, the probability that the heaviest contender won contests was positively associated with the differences of weight and genetic relatedness between contenders. Contrarily, the probability that the contender with greatest wing disc loading won contests was positively associated with differences of weight and negatively associated with the relatedness between contenders. However, these models only explained between 22% and 34% of the variation, respectively. Our results demonstrate that the weight was the major contributor to high dominance values. However, future studies should include (1) the temporal variability of the weight and (2) experimental predictor variables such the burst power of the hummingbirds to evaluate its effects on the dynamics of dominance hierarchies in hummingbird assemblages. All the hummingbird species present in the studied assemblage have developed wide behavioral mechanisms that compensate their morphological differences, which allow them to coexist, even when they compete for the access to the same resource.

Visitation of Heliotrope and Western Purslane Flowers byHesperopsis gracielae(Lepidoptera: Hesperiidae)

We conducted 2 studies on nectar-feeding by MacNeill's sootywing, Hesperopsis gracielae (MacNeill), a rare skipper, near the lower Colorado River in Cibola Valley, Arizona. In the first study, we examined rates of visitation by adults to Heliotropium curassavicum (Boraginaceae) inflorescences and Sesuvium verrucosum (Aizoaceae) flowers on potted plants. Visitation rates per plant or per inflorescence or flower did not differ between species when species were placed alone or together or when plants were placed in sun or shade. Frequencies of landings on both species were greater on plants in sun than shade, suggesting sooty-wings visually respond to flowers when foraging for nectar. In the second study, we measured masses of sugar in H. curassavicum inflorescences on wild plants after visitation by male or female adults. Inflorescences visited by females contained more sugar, but similar numbers of flowers, than those visited by males. Amounts of sugar remaining in inflorescences visited by females, but not males, decreased as visitation-times increased. Ingestion of nectar was apparent only in females. Both plant species can provide H. gracielae adults with nectar in conserved or created habitat.

Pollination and plant reproductive success in restored urban landscapes dominated by a pervasive exotic pollinator

Although insect pollination is fundamental to the persistence of plants in restored habitats, it is rarely taken in to account in evaluations of restoration success. We evaluated a recovery of interactions between the insect-pollinated shrub Dillwynia sieberi and its pollinator assemblage dominated by exotic honeybee Apis mellifera in 5-year-old revegetated pastures and remnants of endangered Cumberland Plain Woodland (the aim of revegetation) in Sydney, Australia. We examined plant size, plant flower density, flower visitation rates by insects, counts of pollen per stigma and presence/absence of germinated pollen, fruit and seed set ratios and rates of pre-dispersal seed predation. Flower densities on plants in restored areas were significantly higher than in forest remnants. Bees were the most common flower visitors. Plants in revegetated areas attracted significantly more flower visitors with visitor assemblages usually dominated by A. mellifera. Plants in revegetated areas had similar numbers of flowers per inflorescence, while fruit and seed set per inflorescence was significantly higher in forest remnants. There was no significant difference in the rates of pre-dispersal seed predation. Plants in revegetated areas and forest remnants had similar seed output with no apparent negative effect of A. mellifera on seed production. Restoration of native vegetation in an urban context is a challenging long-term process. However, introduction of dominant plant species can foster a rapid return of their pollinators. The interactions between the plants and their native pollinators were resilient to pervasive exotic A. mellifera, and plants in restored ecosystems had an adequate reproductive output.

Comparative Efficiency of <I>Nannotrigona perilampoides</I>, <I>Bombus impatiens</I> (Hymenoptera: Apoidea), and Mechanical Vibration on Fruit Production of Enclosed Habanero Pepper

The native bee Nannotrigona perilampoides Cresson (Apidae: Meliponini) has been evaluated with promising results in greenhouse pollination of Solanaceae in Mexico. However, no comparison has been done with imported bumble bees (Apidae: Bombini), which are the most common bees used for greenhouse pollination. We compared the foraging activity and fruit production of habanero pepper. Capsicum chinense Jacquin, by using N. perilampoides and Bombus impatiens Cresson in pollination cages. Both bee species collected pollen on a similar number of flowers per unit time, but N. perilampoides visited significantly more flowers per trip, lasted longer on each flower, and spent more time per foraging trip. Ambient temperature and light intensity significantly affected the foraging activity of N. perilampoides. Light intensity was the only environmental variable that affected B. impatiens. Except for the fruit set, there were not significant differences in the quality of fruit produced by both bee species; however, N. perilampoides and B. impatiens performed better than mechanical vibration for all the variables measured. The abortion of fruit caused the low fruit set produced by B. impatiens, and we speculate it might be due to an excessive visitation rate. Pollination efficiency per visit (Spear's pollination efficiency index) was similar for both bee species in spite of the significantly lower amount of pollen removed by N. perilampoides. We suggested that the highest number of flowers visited per foraging trip coupled with adequate amounts of pollen transported, and transferred between flowers, could explain the performance of N. perilampoides as a good pollinator of habanero pepper. Our experiments confirm that N. perilampoides could be used as an alternative pollinator to Bombus in hot pepper under tropical climates.

Comparative Efficiency of Nannotrigona perilampoides, Bombus impatiens (Hymenoptera: Apoidea), and Mechanical Vibration on Fruit Production of Enclosed Habanero Pepper

The native bee Nannotrigona perilampoides Cresson (Apidae: Meliponini) has been evaluated with promising results in greenhouse pollination of Solanaceae in Mexico. However, no comparison has been done with imported bumble bees (Apidae: Bombini), which are the most common bees used for greenhouse pollination. We compared the foraging activity and fruit production of habanero pepper. Capsicum chinense Jacquin, by using N. perilampoides and Bombus impatiens Cresson in pollination cages. Both bee species collected pollen on a similar number of flowers per unit time, but N. perilampoides visited significantly more flowers per trip, lasted longer on each flower, and spent more time per foraging trip. Ambient temperature and light intensity significantly affected the foraging activity of N. perilampoides. Light intensity was the only environmental variable that affected B. impatiens. Except for the fruit set, there were not significant differences in the quality of fruit produced by both bee species; however, N. perilampoides and B. impatiens performed better than mechanical vibration for all the variables measured. The abortion of fruit caused the low fruit set produced by B. impatiens, and we speculate it might be due to an excessive visitation rate. Pollination efficiency per visit (Spear’s pollination efficiency index) was similar for both bee species in spite of the significantly lower amount of pollen removed by N. perilampoides. We suggested that the highest number of flowers visited per foraging trip coupled with adequate amounts of pollen transported, and transferred between flowers, could explain the performance of N. perilampoides as a good pollinator of habanero pepper. Our experiments confirm that N. perilampoides could be used as an alternative pollinator to Bombus in hot pepper under tropical climates.

CONTROLLED POLLINATION HUSK TOMATO (Physalis ixocarpa Brot.)

Different types of pollination were evaluated in the husk tomato varieties CHF1-Chapingo and Verde Puebla. Treatments consisted of combinations of varieties, covered branches, covered plants and plants under open-pollination (PL). Covering of the two first groups mentioned was done with Agribon, and branches and plants were alone or in pairs of the same or different varieties. In the last group aforementioned (control) plants were without covering. It was used a randomized complete block experimental design with four replications and an experimental plot of on row with three plants. The traits measured by branch or plant were: number of flowers (NFL), number of fruits (NFR) and number of fruits with seed, which was used to calculate the percentage of set flowers (PFLA) and the percentage of fruits with seeds (PFRCS). Results indicated that NFL and NFR from covered branches were statistically lower to those from plants covered in pairs or covered alone; the latter had a similar NFL and lower NFR than plants under PL. The highest PFLA was observed in covered branches (67.9) and PL plants (60.1), and the lowest PFLA was obtained from plants covered alone (45.5). PFRCS from covered branches (5.0), pairs of covered plants (8.5), and alone (4.8) were the same, but inferior to those from plants under PL (29.1). For both NFL and NFR, ‘CHF1-Chapingo’ was superior to ‘Verde Puebla’ under different types of pollination, except for plants under PL; the combination of ‘CHG1-Chapingo’ and ‘Verde Puebla’ in branches was similar to ‘Verde Puebla’, but in plants it was similar to ‘CHF1-Chapingo’. ‘CH1-Chapingo’ and ‘Verde Puebla’ were the same in PFLA and PFRCS under four types of pollination, and the combination o ‘CH1-Chapingo’ and ‘Verde Puebla’ in branches was generally intermediate to both varieties.

ECOLOGICAL DIFFERENTIATION OF COMBINED AND SEPARATE SEXES OFWURMBEA DIOICA(COLCHICACEAE) IN SYMPATRY

The evolution and maintenance of combined vs. separate sexes in flowering plants is influenced by both ecological and genetic factors; variation in resources, partic- ularly moisture availability, is thought to play a role in selection for gender dimorphism in some groups. We investigated the density, distribution, biomass allocation, and physi- ology of sympatric monomorphic (cosexual) and dimorphic (female and male) populations of Wurmbea dioica in relation to soil moisture on the Darling Escarpment in southwestern Australia. Populations with monomorphic vs. dimorphic sexual systems segregated into wet vs. dry microsites, respectively, and biomass allocation patterns and physiological traits reflected differences in water availability, despite similarities in total ramet biomass between the sexual systems. Unisexuals flowered earlier at lower density, and they allocated sig- nificantly more biomass below ground to roots and corms than did cosexuals, which al- located more biomass above ground to leaves, stems, and flowers. Females, males, and cosexuals produced similar numbers of flowers per ramet, but unisexuals produced more ramets than cosexuals, increasing the total number of flowers per genet. Contrary to ex- pectation, cosexuals had significantly higher (more positive) leaf carbon isotope ratios and lower leaf nitrogen content than unisexuals, suggesting that cosexuals are more water-use efficient and have lower rates of photosynthesis per unit leaf mass despite their occurrence in wetter microsites. Cosexuals appear to adjust their stomatal behavior to minimize water loss through transpiration while maintaining high investment in leaves and reproductive structures. Unisexuals apparently maximize the acquisition and storage of both water and nitrogen through increased allocation to roots and corms and enhance the uptake of CO2 by keeping stomata more open. These findings indicate that the two sexual systems have different morphological and physiological features associated with local-scale variation in water availability.

Observations on the Growth of Carnation (Dianthus caryophyllus L.) in Natural and Long Days

Observations were made on the growth and development of carnations grown in containers under natural or 24 h days. The number of leaf pairs produced before flower initiation and the final length of each flowering stem were affected by the date at which the shoot appeared and its position on the plant. Dusk-to-dawn lighting reduced the number of axillary shoots in each generation but increased their rate of development. This resulted in similar numbers of flowers being produced in both treatments.