Post-pollination reproductive isolation between diurnally and nocturnally flowering daylilies, Hemerocallis fulva and Hemerocallis citrina

To examine whether floral and post-pollination isolation develops independently or not, we conducted a crossing experiment between Hemerocallis fulva and Hemerocallis citrina that shows large floral divergence adapted for diurnal and nocturnal pollinators that have been believed to be fully cross-fertile. Flowers of the two species from sympatric populations were hand-pollinated with conspecific pollen from the same population (control), interspecific pollen from the same area (sympatric cross), and interspecific pollen from the different area (allopatric cross). After capsule dehiscence, the fruit set, seed set per fruit and seed set per flower were determined among three cross categories. The seed sets per flower were 32 and 77% lower in sympatric and allopatric crosses than in the control when H. fulva was the pollen recipient. There was no difference in three reproductive measures among the cross categories when H. citrina was the pollen recipient. This finding indicates that post-pollination isolation does exist between H. fulva and H. citrina, although it is partial, asymmetric, and weakened in sympatry. Our result suggests that floral and post-pollination isolation may develop independently, and reinforcement may not be a general phenomenon in plants.     

Seasonal Pattern of Reproduction Of Hizikia Fusiformis (Sargassaceae, Phaeophyta) from Nanao Island, Shantou, China

The maturation pattern of sexual reproduction in Hizikia fusiformis (Harvey) Okamura (Sargassaceae, Phaeaophyta) was examined in 2003 at Yunao Bay, Nanao Island, Shantou, China. Maturation began in mid-April (seawater temperature 19–21 ^∘C), reached the peak in mid-May (maturation rate ca. 70%, and seawater temperature 23.5–25 ^∘C) and finished in late-June (seawater temperature 27.5–30 ^∘C). The Hizikia plants continued to gain the length from the beginning of maturation season to reach a maximum mean length of 34.8 cm in mid-May, after which the mean length was reduced drastically due to the senescence and rupture of the larger plants in size. The major portion of the mature plants belonged to the larger plants between April and May, but to the smaller ones in June. It is suggested that the plant must achieve a critical size before reproductive maturation occurred. There was a positive relationship between the number of receptacles (NR), as well as the reproductive allocation (RA), and the plant size of Hizikia population, with the recorded maximum values of NR and RA being 1220 and 64.3% respectively, for a single plant.     

转GO基因棉花体内H2O2含量的时空表达

研究转GO基因棉花品系B99267-1、B99261及其受体新陆早7号和非转基因棉花品种中棉所12号内源H2O2时空变化。结果表明,在初花期、花铃期和吐絮期三个棉花生育期中,初花期H2O2含量较低,吐絮期最高;各生育期下部和中部叶片H2O2含量普遍高于顶部叶片。棉花叶片组织中GO活性、GO蛋白含量和内源H2O2含量均成正相关,酶活高的叶片GO蛋白含量高、H2O2含量也高。     

A Reconsideration of the Reproductive Biology of the Atlantic Forest in the Volta Velha Reserve

Published species lists that include breeding system designations of vascular plants are rare in the primary literature and, thus, can be potentially valuable sources of information for comparative studies. The published list for vascular plants in the Volta Velha Reserve suffered from a number of errors, notably applying the designation of monoecious to all species with imperfect flowers. Here, I reconsider the breeding systems for 97 woody vascular plant species. The majority of species initially categorized as monoecious are found to be hermaphroditic. I then examine the relationship between breeding system and numbers of individuals in a 1 ha plot. The mean number of individuals was marginally higher in dioecious than hermaphroditic and monoecious species combined. Furthermore, although only 28% of the species were characterized as possessing a dioecious breeding system, 42% of the individuals encountered belonged to a dioecious species. These results suggest that dioecious species can, at least under certain circumstances, overcome the reductions in the number of seed-bearing individuals and mate assurance that accompany possessing spatially segregated sexes.     

广东高州普通野生稻生殖特性的研究Ⅰ.结实率、花粉育性及其发育特点

对采自6个采样点141个编号的高州普通野生稻的结实率、花粉育性及其发育特点进行研究。结果发现,高州野生稻的结实率平均为57．23％,普遍偏低;花粉育性平均为89．3％。育性在50％以上的编号134个,占95．04％;7个编号出现不同程度的败育现象,败育类型以典败为主。其中育性最低的是GZW122,育性仅为8％;17个编号（占12,06％）的裂药性存在严重的异常现象。相关分析表明,花粉育性和裂药性与结实率存在极显著相关。不同采样点问存在一定差异,其中位于祥山镇祥山村祥山洞的编号结实率、花粉育性和裂药指数都较低,变异系数却较大,显示出较丰富的多样性。利用激光扫描共聚焦显微镜术研究发现,高州普通野生稻花粉发育过程与栽培稻一致,同样经历了8个时期,即小孢子母细胞形成期、小袍子母细胞减数分裂期、小孢子早期、小孢子中期、小孢子晚期、二孢花粉期和成熟花粉期。     

Factors affecting breeding habitat selection in a cliff-nesting peregrine Falco peregrinus population

We studied factors affecting breeding habitat selection in a population of cliff-nesting peregrines Falco peregrinus across multiple spatial levels (cliff site, cliff context and land-use of the surrounding landscape), over a 2,100 km² study area in the Alps (Italy and Switzerland). We detected 30 breeding pairs (density: 1.43 territorial pairs/100 km²), whose territories were uniformly distributed over the study area. We compared 15 habitat features characterising occupied cliffs and 30 randomly selected unoccupied cliffs by means of stepwise forward logistic regression and hierarchical partitioning. The logistic regression analysis showed that occupied cliffs were longer (horizontal length), steeper, and had a greater extension of urban areas in the surrounding landscape compared to non-occupied cliffs. The model had a discrimination ability of 0.95. Hierarchical partitioning indicated that the logistic regression model was appropriate. Neither the distance of cliffs to the nearest site occupied by a potential competitor and predator, the eagle owl Bubo bubo, which occurred at a low density (0.67 pairs/100 km²), nor the distance to the nearest site occupied by peregrines had any effect on the cliff suitability model. Therefore, habitat selection in cliff-nesting peregrines was mainly influenced by cliff site features and surrounding landscape characteristics, whereas the proximity to conspecifics and to an intraguild predator had no apparent effects on peregrine settlement in our study population.     

Transmission dynamics of the great influenza pandemic of 1918 in Geneva, Switzerland: Assessing the effects of hypothetical interventions

Recurrent outbreaks of the avian H5N1 influenza virus in Asia represent a constant global pandemic threat. We characterize and evaluate hypothetical public health measures during the 1918 influenza pandemic in the Canton of Geneva, Switzerland. The transmission rate, the recovery rate, the diagnostic rate, the relative infectiousness of asymptomatic cases, and the proportion of clinical cases are estimated through least-squares fitting of the model to epidemic curve data of the cumulative number of hospital notifications. The latent period and the case fatality proportion are taken from published literature. We determine the variance and identifiability of model parameters via a simulation study. Our epidemic model agrees well with the observed epidemic data. We estimate the basic reproductive number for the spring wave R1;=1.49 (95% CI: 1.45-1.53) and the reproductive number for the fall wave R2;=3.75 (95% CI: 3.57-3.93). In addition, we estimate the clinical reporting for these two waves to be 59.7% (95% CI: 55.7-63.7) and 83% (95% CI: 79-87). We surmise that the lower reporting in the first wave can be explained by a lack of initial awareness of the epidemic and the relative higher severity of the symptoms experienced during the fall wave. We found that effective isolation measures in hospital clinics at best would only ensure control with probability 0.87 while reducing the transmission rate by >76.5% guarantees stopping an epidemic.     

Effects of partial throughfall exclusion on the phenology of Coussarea racemosa (Rubiaceae) in an east-central Amazon rainforest

Severe droughts may alter the reproductive phenology of tropical tree species, but our understanding of these effects has been hampered by confounded variation in drought, light and other factors during natural drought events. We used a large-scale experimental reduction of throughfall in an eastern-central Amazon forest to study the phenological response to drought of an abundant subcanopy tree, Coussarea racemosa. We hypothesized that drought would alter the production and the timing of reproduction, as well as the number of viable fruits. The study system comprised two 1-ha plots in the Tapajos National Forest, Para, Brazil: a dry plot where 50% of incoming precipitation (80% throughfall) was diverted from the soil during the six-month wet season beginning in January 2000, and a wet plot that received natural rainfall inputs. Fruit production of C. racemosa was quantified every 15 days using 100 litter traps (0.5 m²) in each plot. The production of new leaves and flowers was recorded monthly for C. racemosa individuals. Soil water, pre-dawn leaf water potential and solar radiation were measured to help interpret phenological patterns. Over the ∼3.5-year period (April 2000 through December 2003), total fruit production remained similar between plots, declining by 12%. In 2003, production was four times higher in both plots than in previous years. In the dry plot, fruit fall shifted 40 and 60 days later into the dry season in 2002 and 2003, respectively. Total fruit fall dry mass production was variable across the study period. Foliage and flower production coincided with peak irradiance early in the dry season until delays in flowering appeared in the dry plot in 2002 and 2003. Plant water stress, through its influence on leaf developmental processes and, perhaps, inhibition of photosynthesis, appears to have altered both the timing of fruit fall and the quality and number of seeds produced.     

Sex, sex-ratios, and the dynamics of pelagic copepod populations

I examine how the population biology of pelagic copepods depends on their mating biology using field data and a simple demographic model. Among calanoid copepods, two distinct patterns emerge. Firstly, copepods that lack seminal receptacle and require repeated mating to stay fertilized have near equal adult sex ratios in field populations. Winter population densities are orders of magnitude less than the critical population density required for population persistence, but populations survive winter seasons as resting eggs in the sediment. Population growth in these species is potentially high because they have on average a factor of 2 higher egg production rates than other pelagic copepods. Secondly, other copepods require only one mating to stay fertile, and populations of these species have strongly female-skewed adult sex-ratios in field populations. Resting eggs have not been described within this group. Winter population sizes are well predicted by the critical density required for population persistence which, in turn, is closely related to the body-size-dependent mate-search capacity. Thus, the different requirements for mating lead in the first case to a more opportunistic reproductive strategy that implies rapid colonization of the pelagic during productive seasons, and in the second case to a strategy that allows maintenance of a pelagic populations during unproductive seasons. Positive density dependent population growth during periods of low population density (‘Allee effect’) amplifies population density variation during winter into the subsequent summer, thus explaining why summer densities appear to depend more on winter densities than on current growth opportunities in pelagic copepods.     

The seminal fluid proteome of the honeybee Apis mellifera

Ejaculates contain sperm but also seminal fluid, which is increasingly recognized to be of central importance for reproductive success. However, a detailed biochemical composition and physiological understanding of seminal fluid is still elusive. We have used MS to identify the 57 most abundant proteins within the ejaculated seminal fluid of the honeybee Apis mellifera. Their amino acid sequences revealed the presence of diverse functional categories of enzymes, regulators and structural proteins. A number have known or predicted roles in maintaining sperm viability, protecting sperm from microbial infections or interacting with the physiology of the female. A range of putative glycoproteins or glycosylation enzymes were detected among the 57, subsequent fluorescent staining of glycolysation revealed several prominant glycoproteins in seminal fluid, while no glycoproteins were detected in sperm samples. Many of the abundant proteins that accumulate in the seminal fluid did not contain predictable tags for secretion for the cell. Comparison of the honeybee seminal fluid proteins with Drosophila seminal fluid proteins (including secreted accessory gland proteins known as ACPs), and with the human seminal fluid proteome revealed the bee protein set contains a range of newly identified seminal fluid proteins and we noted more similarity of the bee protein set with the current human seminal fluid protein set than with the known Drosophila seminal fluid proteins. The honeybee seminal fluid proteome thus represents an important addition to available data for comparative studies of seminal fluid proteomes in insects.