Female benefit,male risk: Polyandry in the true armyworm Pseudaletia unipuncta

In Lepidoptera polyandry is common and females may increase their lifetime reproductive output through repeated matings if they acquire essential resources from male ejaculates. However, the paternity of males mating with previously-mated females is far from assured unless sperm precedence is absolute. In this study on the polyandrous armyworm, Pseudaletia unipuncta, we used two strains of male (the black-eyed wild type and a red-eyed homozygous, recessive mutant), mated with red-eyed females, to determine (i) whether male investment has any impact on female reproductive output, and (ii) if females do benefit from multiple matings, to what extent males fertilize the eggs to which they contributed. Multiple mating resulted in a significant increase in both the fecundity and longevity of females. However, the degree of sperm precedence (those eggs fertilized by the second male) varied from 0–100%, but was not affected by either male size or age, or by the duration of copulation. In cases where sperm precedence was <50% (x = 12%) females produced significantly more eggs (1384 versus 940) prior to the second mating than females where sperm precedence was >50% (x = 89%), indicating that the quality of the first mating influenced the fertilization success of the female's second mate.     

Fitness benefits of multiple mating versus female mate choice in the cellar spider (Pholcus phalangioides)

Recent studies have demonstrated that mating with multiple males can be beneficial for females and her offspring even if males contribute nothing but sperm. This was mainly established for species in which sperm from several males mix in the reproductive tract of the female, thus allowing sperm competition and/or female sperm choice. However, in species with last male sperm precedence, female re-mating decides against the previous male by strongly limiting his reproductive success. We tested the effect of female re-mating behaviour using the cellar spider Pholcus phalangioides, which shows strong last males sperm precedence and moderate levels of polyandry under natural situations. We predicted that females prevented from remating even though they are receptive would show reduced reproductive success compared to females that accept two copulations and females that reject a second male, since the latter two treatments were allowed to behave according to their decisions. However, if the number of matings per se had an effect on oviposition or on offspring performance, double-mated females should perform better compared to both treatments of once-mated females. We measured female fecundity and fertility over a period of 140 days, comparable to the species' natural reproductive peak season. Two thousand one hundred and fifty-two offspring from 67 first egg sacs were reared under two feeding levels. We registered development time and survival, and measured offspring adult size and mass. We found a positive effect of double mating, as in this treatment, oviposition probability was higher compared to the other treatments. Interestingly, adult female offspring of the DM treatment that were raised under low food level had a higher condition index compared to those from FS and RM, but development time, size and mass at adulthood were not affected by mating treatment. Female choice only seemed to affect hatching latency of the offspring. Overall, the main predictor of female reproductive output and success was female body size.     

总量控制费用分摊的多目标规划模型及解法

文章指出了污染物总量控制规划中公平合理分摊优化治理投资费用的重要性，分析了现有的优化治理投资费用分摊方法存在的问题，建立了公平合理分摊优化治理投资费用的多目标规划模型，提出用最短距离理想点法加以求解，并通过实例验证了该方法的合理性。结果表明该模型及解法既可以保证总量控制规划方案的社会整体效益最大，又不失公平，从而确保总量控制规划方案的顺利实施。     

Very low versus undetectable maternal serum alpha-fetoprotein values and fetal death

Very low maternal serum alpha-fetoprotein (MSAFP) levels (<10 ng/mL) are known to be associated with non-viable pregnancies, including conditions such as fetal death, molar pregnancies, and non-pregnancies. There has not been agreement, however, as to whether very low MSAFP levels indicate already existing fetal deaths or are actually predictive. We analysed 230 pregnancies with MSAFP levels <10 ng/mL from among 15 807 women (1.5 per cent) screened consecutively during a three-year period and identified 26 non-viable pregnancies, 22 of which were diagnosed sonographically as part of the screening process (17 missed abortions, 3 blighted ova, 2 non-pregnancies). Furthermore, 20 of these 22 pregnancies were associated with essentially undetectable MSAFP levels (<5 ng/mL). Our data indicate that pregnancies with MSAFP values <5 ng/mL are the group most strongly associated with fetal non-viability and that very low MSAFP values are not strongly predictive for fetal death.     

Progress in developing an ANN model for air pollution index forecast

An air pollution index (API) reporting system is introduced to selected cities of China for public communication on air quality data. Shanghai is the first city in China providing daily average API reports and forecasts. This paper describes the development of an artificial neural network (ANN) model for the API forecasting in Shanghai. It is a multiple layer perceptron (MLP) network, with meteorological forecasting data as the main input, to output the next day average API values. However, the initial version of the MLP model did not work well. To improve the model, a series of tests were conducted with respect to the training method and structure optimization. Based on the test results, the training algorithm was modified and a new model was built. The new model is now being used in Shanghai for API forecasting. Its performance is shown reasonably well in comparison with observation. The application of the old model was only weakly correlated with observation. In 1-year application, the correlation coefficients were 0.2314, 0.1022 and 0.1710 for TSP, SO₂ and NO_x, respectively. But for the new model, for over 8 months application, the correlation coefficients are raised to 0.6056, 0.6993 and 0.6300 for PM₁₀, SO₂, and NO₂. Further, the new algorithm does not rely on manpower intervention so that it is now being applied in several other Chinese cities with quite different meteorological conditions. The structure of the model and the application results are presented in this paper and also the problems to be further studied.     

Female choice in the opportunistic mating of wild chimpanzees (Pan troglodytes schweinfurthii) at Mahale

For female chimpanzees (Pan troglodytes schweinfurthii) in the Mahale Mountains National Park, Tanzania, the most common mating pattern is opportunistic. In such opportunistic matings, females copulated promiscuously but not randomly. This study describes female mate choice during 1-year observation of six females who exhibited regular genital-swelling cycles. During the study period, 169 opportunistic matings and four restrictive matings were recorded over the course of 51 days. As female estrus progressed, mating frequency and the number of adult male mating partners increased, although the number of potential mating partners did not change. Criteria of female choice examined were the direction and consent/rejection of courtship, proximity maintenance, and female grooming. Adult-male courtships were successful more often than those of adolescent males. During the earlier phase of estrus, females copulated rather promiscuously with many males. But during the later phase of estrus when the likelihood of conception is expected to be highest, they copulated repeatedly with high-ranking adult males. There was a positive correlation between female grooming frequency and mating frequency when the likelihood of conception was greatest. Female chimpanzees are thought to choose high-ranking males as fathers of their offspring. Moreover, female chimpanzees may adopt one or both of two mating strategies, i.e., a many-male strategy and a best-male strategy. Received: 23 November 1998 / Received in revised form: 12 April 1999 / Accepted: 26 April 1999     

Multiple mating and facultative polygyny in the Panamanian leafcutter ant Acromyrmex echinatior

Queen mating frequency of the facultatively polygynous ant Acromyrmex echinatior was investigated by analysing genetic variation at an (AG)_n repeat microsatellite locus in workers and sexuals of 20 colonies from a single Panamanian population. Thirteen colonies were found to be monogynous, 5 colonies contained multiple queens, whereas the queen number of 2 colonies remained unresolved. Microsatellite genotypes indicated that 12 out of 13 queens were inseminated by multiple males (polyandry). The mean queen mating frequency was 2.53 and the mean genetically effective paternity frequency was 2.23. These values range among the highest found in ants, and the results are in keeping with the high mating frequencies reported for other species of leafcutter ants. Consistent skew in the proportional representation of different patrilines within colonies was found, and this remained constant in two consecutive samples of offspring. Dissections showed that all examined queens from multiple-queen colonies were mated egg-layers. The mean relatedness value among nestmate workers in polygynous colonies was lower than that for monogynous colonies. No diploid males were detected in a sample of 70 genotyped males. Worker production of males was detected in one queenless colony. We discuss our findings in relation to known patterns of multiple maternity and paternity in other eusocial Hymenoptera. Received: 2 September 1998 / Received in revised form: 3 February 1999 / Accepted: 7 February 1999     

基于数字图像比色法测定水中氟化物

在酸性溶液中,氟能破坏二甲酚橙〖CD*2〗锆显色体系,使溶液颜色从紫红色变为橙色或黄色,通过采集图像颜色信息构建3个特征颜色分量的多元线性回归模型,用以定量测定水中氟。该方法在0 mg/L~1.5 mg/L范围内线性良好,方法检出限为0.03 mg/L。两个质量浓度水平的氟化物标准溶液6次测定结果的RSD分别为1.4%和1.3%,相对误差分别为0.3%和1.7%。     

An extension of Multiple Greek Letter method for common cause failures modelling

Common cause failure describes a condition where several components share the same source of failure that causes them to fail or become unavailable simultaneously. The objective of this paper is to present an improved approach to common cause failure modelling within reliability analyses. The currently used methods allow one component to share common characteristics with only one group of components, which may be affected by the same source of failure. Therefore, an improved method was developed, where components can be assigned to several groups of components that are susceptible to faulty operation with respect to their similar characteristics. A mathematical derivation of the method is presented and the theory is applied to smaller theoretical samples and to a simplified real example. The results show that the new method enables a more detailed reliability analysis. The results prove that consideration of common cause failures using the improved method may decrease the system reliability compared to traditional common cause failure consideration. The system reliability decreases more, if the redundant components have more similarities and are therefore assigned to several common cause failure groups.     

A heuristic approach to predicting water beetle diversity in temporary and fluctuating waters

An understanding of the causal mechanisms and processes that shape macroinvertebrate communities at a local scale has important implications for the management and conservation of freshwater biodiversity. Here we compare the performance of linear and non-linear statistics to explore diversity-environment relationships using data from 76 temporary and fluctuating ponds in two regions of southern England. We focus on aquatic beetle assemblages, which have been shown to be excellent surrogates of wider freshwater macroinvertebrate diversity. Ponds in the region contained a rich coleopteran fauna, totaling 68 species, which provided an excellent model system with which to compare the performance of two non-linear procedures (artificial neural networks—ANNs and generalised additive models—GAMs) and one more traditional linear approach (Multiple linear regression—MLR) to modelling diversity-environment relationships. Of all approaches employed, the best fit was obtained using an ANN model with only four input variables (conductivity, turbidity, magnesium concentration and depth). This model accounted for 82% of the observed variability in Shannon diversity index across ponds. In contrast, the best GAM and MLR models only explained 50% and 14% of this variation, respectively. Contribution profile analysis of conductivity, turbidity, magnesium concentration and depth, obtained from the best fit ANN through a hierarchical cluster analysis, allowed the identification of direct and proxy effects in relation to the environmental variables measured in this study. In each case, distinct clusters of ponds were identified in contribution profile analysis, suggesting that ponds across the two regions fall into a number of discrete groups, whose beetle faunas respond in subtly yet significantly different ways to key environmental variables. Aquatic coleopteran diversity in ponds in the two regions appears to be driven at a local scale by changes in relatively few physicochemical gradients, which are related to diversity in a clearly non-linear manner.