Heterozygosity and selective value: the case of the marine fish,Diplodus sargus (Linné, 1758)

A total of 842 white sea bream (Diplodus sargus), sampled in Banyuls-sur-Mer, were analysed to test 'genotype-phenotype' relationship for various characters related to the fitness. The results show significant differences (MLH and FIS) for the age according to the sex between females carrying out and not carrying out sexual inversion. This suggests an overdominance for old females and a genetic sex determination. The individuals laying very early during the period of reproduction are also differentiated from the individuals reproducing later in the season. These results suggest either a stable calendar of laying in time separating the individuals genetically reproducing precociously from the others and this by differential selection and/or genetic drift either a Wahlund effect among cohorts.     

Estimating the variation,autocorrelation, and environmental sensitivity of phenotypic selection

Despite considerable interest in temporal and spatial variation of phenotypic selection, very few methods allow quantifying this variation while correctly accounting for the error variance of each individual estimate. Furthermore, the available methods do not estimate the autocorrelation of phenotypic selection, which is a major determinant of eco‐evolutionary dynamics in changing environments. We introduce a new method for measuring variable phenotypic selection using random regression. We rely on model selection to assess the support for stabilizing selection, and for a moving optimum that may include a trend plus (possibly autocorrelated) fluctuations. The environmental sensitivity of selection also can be estimated by including an environmental covariate. After testing our method on extensive simulations, we apply it to breeding time in a great tit population in the Netherlands. Our analysis finds support for an optimum that is well predicted by spring temperature, and occurs about 33 days before a peak in food biomass, consistent with what is known from the biology of this species. We also detect autocorrelated fluctuations in the optimum, beyond those caused by temperature and the food peak. Because our approach directly estimates parameters that appear in theoretical models, it should be particularly useful for predicting eco‐evolutionary responses to environmental change.     

The statistical analysis of potato anther culture data

Methods for the production and utilisation of haploids have been developed for a range of crop plants. Genetical and environmental factors are known to influence both the rate of haploid induction and the mode of regeneration. Investigations designed to examine the parameters that influence haploid production from anthers are usually based on the overall percentage of responding anthers. Previous studies have rarely taken into account the frequency or distribution of anther culture response within a potato flower. In this paper the binomial, poisson and multiplicative binomial distributions are used for the first time to describe the distribution of anther culture response within a Solanum tuberosum flower.     

Shiftwork and Sickness Absence Among Police Officers: The BCOPS Study

Shiftwork, regarded as a significant occupational stressor, has become increasingly prevalent across a wide range of occupations. The adverse health outcomes associated with shiftwork are well documented. Shiftwork is an integral part of law enforcement, a high-stress occupation with elevated risks of chronic disease and mortality. Sickness absence is an important source of productivity loss and may also serve as an indirect measure of workers’ morbidity. Prior studies of shiftwork and sickness absenteeism have yielded varying results and the association has not been examined specifically among police officers. The objective of this study was to compare the incidence rate of sick leave (any, ≥3 consecutive days) among day-, afternoon-, and night-shift workers in a cohort of police officers and also examine the role of lifestyle factors as potential moderators of the association. Participants (N?=?464) from the Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) study examined between 2004 and 2009 were used. Daily work history records that included the shift schedule, number of hours worked, and occurrence of sick leave were available for up to 15 yrs starting in 1994 to the date of the BCOPS study examination for each officer. Poisson regression analysis for ungrouped data was used to estimate incidence rates (IRs) of sick leave by shift, and comparison of IRs across shifts were made by computing incidence rate ratios (IRRs) and their 95% confidence intervals (CIs). Sick leave occurred at a higher rate on the night shift (4.37 per 10?000 person-hours) compared with either day (1.55 per 10?000 person-hours) or afternoon (1.96 per 10?000 person-hours) shifts. The association between shiftwork and sickness absence depended on body mass index (BMI). For overweight individuals (BMI?≥?25?kg/m²), the covariate-adjusted incidence rate of sick leave (≥1 day) was twice as large for night-shift officers compared with those working on the day (IRR?=?2.29, 95% CI: 1.69–3.10) or afternoon (IRR?=?1.74, 95% CI: 1.29–2.34) shift. The IR of three or more consecutive days of sick leave was 1.7 times larger for those working on night shift (IRR?=?1.65, 95% CI: 1.17–2.31) and 1.5 times larger for those working on afternoon shift (IRR?=?1.50, 95% CI: 1.08–2.08) compared with day shiftworkers. For subjects with normal BMI (<25?kg/m²), the incidence rates of sick leave did not differ significantly across shifts. In conclusion, shiftwork is independently associated with sickness absence, with officers who work the night shift having elevated incidence of sick leave. In addition, overweight officers who work the night shift may be at additional risk for sickness absence.     

Statistical analysis of temporal evolution in single-neuron firing rates

A fundamental methodology in neurophysiology involves recording the electrical signals associated with individual neurons within brains of awake behaving animals. Traditional statistical analyses have relied mainly on mean firing rates over some epoch (often several hundred milliseconds) that are compared across experimental conditions by analysis of variance. Often, however, the time course of the neuronal firing patterns is of interest, and a more refined procedure can produce substantial additional information. In this paper we compare neuronal firing in the supplementary eye field of a macaque monkey across two experimental conditions. We take the electrical discharges, or 'spikes', to be arrivals in a inhomogeneous Poisson process and then model the firing intensity function using both a simple parametric form and more flexible splines. Our main interest is in making inferences about certain characteristics of the intensity, including the timing of the maximal firing rate. We examine data from 84 neurons individually and also combine results into a hierarchical model. We use Bayesian estimation methods and frequentist significance tests based on a nonparametric bootstrap procedure. We are thereby able to conclude that a substantial fraction of the neurons exhibit important temporal differences in firing intensity across the two conditions, and we quantify the effect across the population of neurons.     

广东澳头红树植物群落的物种多样性与种群分布格局研究

广东澳头红树植物群落的物种多样性与种群分布格局研究陈桂珠,缪绅裕（中山大学环科所,中山大学生物系,广州５１０２７５）ＳｐｅｃｉｅｓＤｉｖｅｒｓｉｔｙａｎｄＰｏｐｕｌａｔｉｏｎＤｉｓｔｒｉｂｕｔｉｏｎＰａｔｔｅｒｎｏｆＭａｎｇｒｏｖｅＣｏｍｍｕｎｉｔｙ...     

数字PCR技术及应用研究进展

数字PCR是继实时定量PCR之后新兴发展起来的一种绝对定量分析技术。通过将单个DNA分子转移入独立的反应室,PCR扩增反应后,对荧光信号进行检测分析,实现单分子的绝对定量。数字PCR技术摆脱了对标准曲线的依赖,具有更高灵敏度和准确度,在基因突变检测、拷贝数变异检测、微生物检测、转基因食品检测以及下一代测序等方面均得到广泛应用。本文介绍数字PCR技术的定量方法,并评述该技术在主要应用领域的研究进展。