Effect of climate change on mast-seeding species: frequency of mass flowering and escape from specialist insect seed predators

Global surface temperatures are expected to increase by several degrees in the next century, with potentially large but poorly understood impacts on ecological interactions. Here we propose potential effects of increased temperatures on ecologically dominant New Zealand grasses (Chionochloa spp.) that mass flower and mast seed. Twenty-two years’ data from five masting Chionochloa species in New Zealand showed that the cue for heavy flowering was unusually high temperature in the summer of the year before flowering. Attack by predispersal insect seed predators was much reduced in mast years, apparently because predator populations were satiated. Increased temperatures would greatly decrease interannual variation in Chionochloa flowering, allowing seed predator populations to increase and potentially to devastate the seed crop annually. Similar responses are likely in masting species worldwide. This previously unrecognized effect of global warming could have widespread impacts on temperate ecosystems.     

Interactions between plant and insect diversity in the restoration of lowland calcareous grasslands in southern Britain

Abstract. The lowland calcareous grasslands of northwestern Europe are highly prized by ecologists and conservationists as a result of the diversity of their plant and invertebrate communities. Large areas of such grasslands have been lost this century as a result of changes in agricultural land use. Recent changes in agricultural policies, in particular the introduction of agri-environmental incentive schemes, have resulted in an increasing area being managed for the restoration of these communities. This paper reviews the management techniques employed in the restoration of lowland calcareous grasslands and the factors that govern their success. Constraints on the enhancement of the plant diversity of restoration sites include high soil fertility and the presence of undesirable species in the soil seed bank. However, it is thought that the primary constraint is the availability of propagules from which new populations can be established. Similarly, the dispersal mode and ability of insect species is likely to be the major factor limiting the enhancement of insect diversity. Evaluation of the success of restoration management usually involves monitoring changes in the plant community. However, as a result of their short life-cycles and sensitivity to small-scale environmental conditions, insects may respond more rapidly to changes resulting from restoration management and therefore provide better indicators of success. With the exception of a few high-profile butterfly species, the use of insects as indicator taxa has largely been neglected in terrestrial systems. This paper illustrates their potential use with reference to lowland calcareous grasslands in southern Britain.     

Changes in estuarine nematode communities following a decrease of organic pollution

The response of a nematode community to a decreasing organic matter loading was studied. Monthly observations were made at three stations at an intertidal brackish-water mudflat in the Ems estuary in 1980 (highly polluted), 1987 (moderately polluted) and 1993 (no significant pollution). Nematodes were identified and counted in the upper 1 cm of the sediment.The decrease of organic pollution was followed by an increase in species diversity, whereas numerical densities decreased. Diatom eating nematodes, being dominant under eutrophic conditions in 1980, decreased strongly, partly as a consequence of decreasing diatom standing stock. Eudiplogaster pararmatus, an indicator of organic enrichment, decreased strongly to disappear completely in 1993. Bonger's maturity index was used to describe the response of the nematode community. At 2 most polluted stations a strong response was observed from 1980 to 1987: a decrease of colonizer species. After 1987, although persister species increased, no further development towards a more natural succession type community occurred, probably due to the natural stress of the habitat (high mudflat, low salinities).     

我国东、南沿海地区AM真菌群落生态分布研究

在我国东、南沿海地区AM真菌资源调查的基础上研究了AM真菌的群落生态分布和特征。证明球囊霉属在该地区的出现频度和相对多度都最高,其次是硬囊霉属。该区内南四省AM真菌丰度、密度和物种多样性指数均比北三省高。聚类分析结果和上述相似,说明我国东、南沿海各省AM真菌的丰度、频度、密度、多度和多样性特征由北向南呈规律性变化。     

雄性核不育水稻育性转换的光周期效应指数值(PE)和温度效应指数值(TE)的遗传性初步研究

对比考察了农垦５８ｓ与７００１ｓ、８９０２ｓ与培矮６４ｓ及８９０２ｓ与安农Ｓ１等３个光（温）敏核不育水稻杂交组合的双亲、Ｆ１、Ｂ１、Ｂ２和Ｆ２世代的样本及每一个体的ＰＥ和ＴＥ的变异。无论双亲核不育基因的等位程度及栽培环境的光、温周期如何,在多数情况下都显示了如下的规律：（１）后代样本ＰＥ、ＴＥ的大小虽然形形色色,但都取决于其双亲。Ｆ１表示完全显性甚至超显性。（２）Ｆ２个体的ＰＥ或ＴＥ、尤其同一个体ＰＥ与ＴＥ的集成类型发生有规律的分离和超亲分离,产生形形色色的育性转换类型。在纯粹由雄性不育个体组成的Ｆ２不育分样本中也发生同样分离。（３）ＰＥ或ＴＥ的广义遗传力的估值都大于５０％。据此推断ＰＥ、ＴＥ是两个可遗传并可供选择的独立性状;并对育性转换现象的遗传机制也进行了讨论。     

Body Anthropometry and the Risk of Hip and Wrist Fractures in Men: Results from a Prospective Study

Available epidemiological information on the associations between body anthropometry and the incidence of fractures in men is limited. We therefore prospectively investigated the association between body anthropometry and the incidence of hip and wrist fractures from low and moderate trauma among 43,053 men who were 40 years to 75 years of age in 1986 when they first enrolled in the Health Professionals Follow-Up Study. After 8 years of follow-up, 201 wrist fracture cases and 56 hip fracture cases were reported. Greater height was associated with significant elevations in both hip and wrist fractures, whereas nonsignificant inverse associations were observed with weight and body mass index. Men in the highest quintile of waist circumference had a relative risk (RR) of 2.57 (95% confidence interval [CI] 0.64 to 10.3) for hip fracture and 2.05 (95% CI 1.06 to 3.96) for wrist fracture when compared with men in the lowest quintile. Waist-to-hip ratio was also positively related to fracture incidence; comparing highest with lowest quintile, the RRs were 3.92 (95% CI 1.07 to 14.3) for hip fracture and 1.50 (95% CI 0.85 to 2.66) for wrist fracture. These anthropometric indicators, in particular waist-to-hip ratio, may be useful for the prediction of hip fracture in adult men.     

Effects of lairage temperature and holding time on pig behaviour and on carcass and meat quality

Twenty three groups of about 30 pigs each were kept in an environmentally controlled room in lairage, at temperatures of 20 or 35°C for periods of 0.5 or 3 h, to establish the effects of these parameters on animal behaviour and meat quality. Following initial exploration, 50% of pigs kept at 35°C but only 5% kept at 20°C lay down before the end of the 0.5 h period. Seven percent of pigs fought in both temperature conditions. When held in lairage for 0.5 h there was no difference in meat quality or skin damage at either temperature. When held for 3 h, about 95% of pigs were lying down after 2 h in the pens. Again, the percentage of animals fighting was similar for both temperatures, the number of encounters increasing during the first 30–40 min. The more intense initial fighting within the group held at 35°C resulted in the pigs lying down slightly earlier. Irrespective of the lairage time, the frequency of sexual activity decreased with temperature. The proportion of carcasses with skin damage increased with lairage time due, perhaps, to the longer duration of aggressive encounters. Increased lairage time at 20°C reduced the incidence of PSE meat, but at 35°C the longer lairage time showed no benefit to animal welfare or meat quality.     

重庆机场草地土壤动物群落特征及其与鸟类关系的初步研究

对重庆机场草地土壤动物群落的组成,结构和时空动态特征进行了比较研究,初步分析了土壤动物与机场鸟类在种类和数量上的动态关系。结果表明：土壤动物的优势类群为蜱螨目;常见类群多为大,中型土壤动物,是鸟类捕食的主要对象;活动性弱的小型土壤动物是幼虫主要分布在土壤和腐质层中,且群落的多样性和稳定性较高;     

Indices of reproductive skew depend on average reproductive success

Several indices of reproductive skew, which quantify the degree of unequal partitioning of reproductive output among members in an animal society, have been proposed. Here we point out the drawbacks of these indices. The most serious problem is the dependence of the indices on mean reproductive success: skew values tend to be larger, as average numbers of offspring decrease, due to random sampling error in numbers of offspring. Thus it is difficult to compare societies with different average lifetime reproductive success using these indices, even though we have presented methods to calculate the expected reproductive skew caused by random sampling error, especially when average numbers of offspring are small, as is often the case with cooperatively breeding vertebrates. As an alternative, we propose using the spatial dispersion indices of population ecology (Morisita's index or its standardized version) for the measurement of reproductive skew. These indices are almost independent of average fecundity and have their own method of testing for random variation in offspring numbers. This revised version was published online in July 2006 with corrections to the Cover Date.