Pollinator probing preference and switching mode-mediated self-interference within a monoecious plant significantly reduced reproductive fitness

Introduction

Monoecy is usually interpreted as an important evolutionary route of the plant sexual system from hermaphroditism to dioecy. This floral mechanism can effectively reduce self-interference during the reproductive process, and the services provided by pollinators may play an essential role in monoecious species; however, relevant research is still lacking. Thus, we aimed to determine whether monoecious plants could effectively avoid self-interference and promote the evolution of monoecy under the service of pollinators.

Methods

Here, we successfully performed manipulation experiments to test self-compatibility, pollinator behavior, and self-interference between male and female functions in Akebia trifoliata, a typical monoecious species.

Results

We demonstrated that experimental self-pollination did not yield any fruit, and supplemental pollination significantly increased fruit set and fruit weight compared to natural pollination, suggesting that this species is completely self-incompatible and experiences strong pollen limitation. Simultaneous self- and cross-pollination and self-pollination prior to cross-pollination significantly reduced reproductive fitness, but self-pollination after cross-pollination did not, indicating self-interference in this plant. Moreover, both male flower probing preference and switching modes within inflorescences by pollinators successfully reinforced self-interference and were also responsible for decreasing reproductive fitness in A. trifoliata.

Discussion

In summary, pollinator-mediated self-interference significantly reduced selfing, providing potential dynamics for the maintenance and evolution of monoecy.

The effects of local variation in light availability on pollinator visitation, pollen and resource limitation of female reproduction in Hosta ventricosa

BACKGROUND

Light availability may have direct effects on reproduction through resource availability, and indirect effects on female reproduction by influencing plant-pollinator interactions. Floral display size, pollinator visitation per flower, resource and pollen limitation of fruit and seed production were quantified in a forested patch and an adjacent open patch of two populations of the perennial herb Hosta ventricosa.

RESULTS

Plants in the open patch produced significantly larger floral displays than those in the forested patch in both populations. Floral display size had a positive effect on pollinator visitation rate per flower in one population, but no effect in the other. Plants in the open patch received approximately 8-11 times more visitation rates and produced significantly more fruit and seeds per flower than those in the forested patch. However, supplemental pollination resulted in significantly more fruit and seed production per flower compared to natural pollination in the forested patch but not in the open patch in one population, and did not enhance fruit and seed production in either the forested or the open patch in the other. In both populations, supplementally pollinated plants in the open patch produced significantly more fruit and seeds per flower than supplementally pollinated plants in the forested patch.

CONCLUSIONS

In H. ventricosa, local variation in light conditions could affect pollinator activity and influence female reproduction through resource availability; however differences in the degree of pollen limitation between local habitats were found to be population-specific.

Evaluation of pollinator effectiveness based on pollen deposition and seed production in a gynodieocious alpine plant, Cyananthus delavayi

Examining variations in pollinator effectiveness can enhance our understanding of how pollinators and plants interact. Pollen deposition and seed production after a single visit by a pollinator are often used to estimate pollinator effectiveness. However, seed production is not always directly related to pollen deposition because not all pollen grains that are deposited on a stigma are compatible or conspecific. In the field, we tested pollinator effectiveness based on pollen deposition and the resulting seed production after single visits by different pollinator groups in a gynodieocious alpine plant Cyananthus delavayi (Campanulaceae). Our results showed that mean pollen deposition was generally inconsistent with mean seed production when comparisons were performed among different pollinator groups and sexes. In general, the correlations were not significant between pollen deposition and seed production in both perfect and female flowers after single visits by halictid bees, bumble bees, and hoverflies. We suggest seed set of virgin flowers after single visits is a more reliable indicator of pollinator effectiveness than pollen deposition and would be a better indicator of pollinator effectiveness for future studies.

Electronic and magnetic properties of epitaxial perovskite SrCrO₃(0 0 1)

We have investigated the intrinsic properties of SrCrO3 epitaxial thin films synthesized by molecular beam epitaxy. We find compelling evidence that SrCrO3 is a correlated metal. X-ray photoemission valence band and O K-edge x-ray absorption spectra indicate a strongly hybridized Cr3d-O2p state crossing the Fermi level, leading to metallic behavior. Comparison between valence band spectra near the Fermi level and the densities of states calculated using density functional theory (DFT) suggests the presence of coherent and incoherent states and points to strong electron correlation effects. The magnetic susceptibility can be described by Pauli paramagnetism at temperatures above 100 K, but reveals antiferromagnetic behavior at lower temperatures, possibly resulting from orbital ordering.

Scale-dependent effects of habitat fragmentation on reproduction in the annual Circaeaster agristis, a narrow endemic and threatened species

BACKGROUND

Habitat fragmentation and the resulting decline in population size and density commonly reduce the reproduction of rare and threatened species. We investigated the impacts of population size and density on reproduction in more than 30 populations of Circaeaster agristis, a narrow endemic and threatened species, in 2010 and 2011. We also examined the effects of NND (nearest neighbor distance) and LNS (local neighbor size), within radii of 0.1 m, 0.2 m and 0.3 m, on reproduction in two of the populations in 2011.

RESULTS

Population size did not affect fruit (seed) number and fruit set in either year studied. Population density had an indirect negative effect on fruit number and fruit set as a consequence of a negative effect on plant size in 2010, but had no effect on fruit number and fruit set in 2011. Within populations, individual fruit number did not change, and individual fruit set increased independent of plant size, in response to increasing NND. Both individual fruit number and individual fruit set increased, independent of plant size, with increases in LNS within a 0.1 m radius, but did not change with increases in LNS within radii of between 0.1 m and 0.2 m radii or between 0.2 m and 0.3 m.

CONCLUSIONS

The effect of habitat fragmentation on reproduction of C. agristis is scale-dependent. In contrast to the generally accepted idea that fragmentation reduces plant reproduction, reproductive success may increase in sparse populations or increase in response to decreases in LNS in C. agristis.

Lack of pharmacokinetic drug interactions between tiagabine and carbamazepine or phenytoin

Two single-center, open-label studies examined the potential effects of tiagabine on the pharmacokinetics and safety of carbamazepine and phenytoin at steady state. Twelve adult patients with seizures controlled by an individualized fixed dosage of antiepilepsy medication (carbamazepine or phenytoin) participated in each study. On day 1, the pharmacokinetics of the baseline antiepilepsy drug were determined. On days 2 through 18, tiagabine was titrated from 8 to 48 mg/d (or the maximum tolerated dose up to 48 mg/d), and the usual fixed dosage of carbamazepine or phenytoin was continued. The pharmacokinetic assessment was repeated on day 18. There were no statistically significant differences in carbamazepine, carbamazepine epoxide, and phenytoin pharmacokinetic parameters when either drug was administered alone or in combination with tiagabine. In each study, 11 of 12 patients (92%) experienced treatment-emergent adverse events after tiagabine was added. The most frequent adverse events were dizziness, headache, difficulty concentrating, drowsiness, and tremor. Most symptoms were mild or moderate in severity and resolved without further treatment, although tiagabine dosage reductions were required by 4 patients in the carbamazepine study and by 3 patients in the phenytoin study. There were no clinically important effects on physical examination or neurologic test results, laboratory values, or vital signs. The results suggest that addition of tiagabine to a fixed regimen of either carbamazepine or phenytoin is generally well tolerated and that carbamazepine and phenytoin steady-state pharmacokinetics are unaffected by the addition of tiagabine.

[Intracranial arachnoid cyst: report of 23 cases]

Twenty-three cases of intracranial arachnoid cyst are reported. Among them 8 cases developed primarily and 15 secondarily. There are 19 male and 4 female, ages ranged 3 to 40 years. The duration of illness were one month to 32 years. There are 19 cases located supratentoriumly and 4 subtentoriumly. Most of them were situated at Sylvius fissure (13 cases). 22 cases were treated by partial resection of the cyst and different kinds of shunt operations. Short-term follow-up study showed that the results were excellent without operative death. The etiology, pathogenesis, diagnosis of this disease and operative indications are discussed.