Extrapair paternity in the swamp sparrow, <Emphasis Type="Italic">Melospiza georgiana</Emphasis>: male access or female preference?

Over the past two decades, the combination of molecular and field methods has revealed considerable variation in the level of extrapair fertilizations among socially monogamous birds. Models predicting extrapair young range in scale from a single population to multiple Orders, and there is no single, unifying theory for these reproductive tactics. We investigated proximate explanations of extrapair fertilizations in two subspecies of the swamp sparrow, Melospiza georgiana georgiana and Melospiza georgiana nigrescens, across a range of social and environmental conditions. The presence of extrapair young was best predicted by the size of two male plumage badges (one correlated with parental care and one with territorial aggression) relative to the badge size of their immediate neighbors, the interaction of these two measures, mean territory size, and the maximum size of the aggression badge among neighbors. The size of the male’s parental care badge (relative to neighbors) was negatively correlated with the probability of lost paternity. The relative size of the aggression badge was positively correlated with the presence of extrapair young when the parental care badge was small and negatively correlated when the badge was large. Controlling for these crown measures, males with larger territories were less likely to suffer losses in paternity. There was no effect of breeding density, breeding synchrony, their interaction, subspecies, or weather during the fertile period on the presence of extrapair young. These results suggest that female preference for males that provide more parental care (or preference for genes that convey this trait) plays a dominant role in extrapair interactions among swamp sparrows. Models based on female assessments of relative mate quality offer a promising explanation of patterns in extrapair fertilizations among bird species.     

Influence of male harassment and female competition on female feeding behaviour in a sexual–asexual mating complex of mollies (<Emphasis Type="Italic">Poecilia mexicana</Emphasis>, <Emphasis Type="Italic">P. formosa</Emphasis>)

Differential interests between the sexes regarding the number of copulations can result in sexual harassment. Hence, females may have less time available for foraging. Male sexual harassment often leads to fitness reduction in females. We used the mating complex of the bisexual fish Poecilia mexicana and the co-occurring all-female Poecilia formosa to study sexual harassment and its incurred cost on female feeding efficiency. P. formosa is a sperm-dependent parthenogen that requires mating with host males to induce embryogenesis, but the male genes are not used. We therefore predicted P. mexicana males to prefer conspecific females. Hence, costs of male sexual harassment should not occur in unisexuals. While P. formosa are at a disadvantage compared to P. mexicana females due to male mate choice (leading to sperm limitation), this could be traded-off by suffering less from sexual harassment. In our experiment, we found males to direct significantly more pre-copulatory mating behaviour towards conspecific females, whereas actual mating attempts did not differ between species. Contrary to our prediction, both types of females started feeding later and spent less time feeding in the presence of a male partner compared to the time spent feeding with another female, suggesting that females of both species suffer from male harassment. The focal females' feeding time declined with increasing body size of the female competitor, and the same pattern was found when a male was present. We discuss that—besides sexual harassment—other factors such as food competition and female mate choice may affect female feeding efficiency.     

轻烃类VOCs在活性炭上的动态吸附行为

采用BET,XRD,FTIR技术对两类椰壳活性炭进行了表征,考察了空速和吸附温度对正戊烷和正己烷动态吸附穿透容量(DPC)及穿透时间的影响,并对正戊烷和正己烷的二元竞争吸附过程进行了研究。结果表明:两类活性炭材料的组成和官能团结构相似,具有大量微孔的片状活性炭(FAC)有利于轻烃类VOCs的吸附;采用FAC吸附正己烷时,DPC对空速和温度变化不敏感;二元竞争吸附过程中,开始阶段正戊烷和正己烷同时被吸附,随后已被吸附的正戊烷被强吸附质正己烷部分置换,直至正己烷吸附饱和,与一元吸附相比,正己烷的DPC和饱和吸附容量略有增加,正戊烷的DPC和饱和吸附容量大幅降低。     

不同碳减排政策对内外资企业竞争力的影响比较

一方面,由于我国内外资企业的生产效率和碳排放效率差距较大,不同的碳减排政策势必会对内外资企业的市场竞争力带来不同的影响;另一方面,已有文献大多在完全竞争的框架下对不同减排政策的实施效应进行分析,而事实上我国碳减排政策所覆盖的产业大多是不完全竞争甚至是寡头垄断。由此,我们基于内外资企业存在低碳技术差距这一新的研究视角,通过构建两阶段博弈模型来比较分析相同碳强度减排目标下强制减排、碳税与碳交易等三种减排政策对内外资企业产量、市场份额及其社会总产量的影响,从而有利于我国从妥善处理内外资关系的角度制定更有针对性的减排政策。结果表明:(1)三种减排政策都降低了内资企业的产量和市场份额,且内外资企业低碳技术差距越大时内资企业的市场份额下降越多。(2)强制减排降低了社会总产量,碳税和碳交易同等幅度地减少了社会总产量。(3)最优税率仅仅是减排目标的增函数。(4)市场出清的碳交易价格和碳税税率相等,且其数值仅与减排目标正相关,而与碳排放权的分配无关。(5)碳交易比碳税更有利于"保护"内资企业的市场竞争力。相关政策启示如下:(1)尽快确定普适的碳排放核算标准,核算出各行业内外资企业的低碳技术差距;(2)尽快在全国范围内启动碳交易机制,建立促进缩小内外资企业低碳技术的机制;(3)在碳交易市场条件不成熟的行业可以率先推出碳税政策;(4)政府应该根据内外资企业低碳技术差距来对不同行业采取最适宜的减排政策,而非"一刀切"。     

环境监测市场化若干问题的思考

分析了环境监测市场化迅速发展的原因。论述了政府在环境治理中的角色和环境监测的本质属性,通过环境监测产品使用价值分析,提出了购买者为排污企业时,环境监测产品使用价值的错位概念。论述了环境监测市场化可能导致的恶性竞争。     

间接竞争ELISA法测定稻田土壤中除草剂毒莠定的残留量

通过对反应体系中酶标二抗(辣根过氧化物酶标记羊抗兔IgG)和抗体的最佳稀释浓度等条件的筛选和确定,最终建立了一种快速灵敏地测定污染稻田土壤中毒莠定残留量的方法--间接竞争ELISA分析方法.结果表明,酶标二抗和抗体的最佳稀释度均为1:500(体积比),毒莠定的检出下限达到5 ng·mL-1,在0.07～0.7μg·mL-1浓度范围内有良好的线性;土壤浸出液加样的平均回收率为104.11%,变异系数在3.13%～11.13%之间,符合农药残留分析的要求;样品基质对检测结果没有干扰.     

Socioecological influences on the dispersal of female mountain gorillas—evidence of a second folivore paradox

Socioecological models indicate that the group structure and female dispersal patterns of primates are determined primarily by the abundance and distribution of food, predation pressures, and infanticide risks. In response to those influences, females of folivorous primates are considered relatively free to disperse into groups with the optimal size and structure. Yet some folivores live in small groups despite a potentially higher risk of predation, an apparent inconsistency known as the folivore paradox. This paper examines the female dispersal of a folivorous primate, the Virunga mountain gorillas. Mountain gorillas currently have no natural predators, but this species presents a different version of the folivore paradox: why do 50–60% of females reside in smaller one-male groups despite a higher risk of infanticide? In this study, females left one-male groups more frequently than multimale groups, but transfer destinations were not consistently biased toward multimale groups and those groups did not have higher immigration rates. We found no evidence of dispersal to avoid feeding competition within large groups, even as they have become three to five times larger than average. Thus, the lack of a consistent bias toward multimale groups was not because they are typically larger than one-male groups. Instead, the apparent inconsistencies may reflect limited female transfer opportunities, other influences on dispersal, and possibly an evolutionary disequilibrium in which current behavior does not optimize fitness.     

Coupling soil water and shoot dynamics in three grass species: A spatial stochastic model on water competition in Neotropical savanna

Savannas are ecosystems known for their high environmental and economic value. They cover at least 20% of the global land surface and, in some cases, can act as a boundary between tropical rainforest and deserts. Water is an important determinant of savanna ecosystems.In this paper, we present a theoretical stochastic model of root competition for water, which couples, soil water availability, phenology, and root and shoot architecture applied to three Neotropical savanna grasses. Soil moisture was simulated using a daily balance, as proposed by Rodriguez-Iturbe et al. [Rodriguez-Iturbe, I., Porporato, A., Ridolfi, L., Isham, V., Cox, D.R., 1999. Probabilistic modelling of water balance at a point: the role of climate, soil and vegetation. Proc. R. Soc. London, Ser. A 455, 3789–3805.]. To simulate rainfall stochasticity, we used daily precipitation data from the airport weather station in the State of Barinas, Venezuela, for the period 1991–2007. Competition among neighbouring plants took into account the spatial distribution of the individuals. As a final step, the model allowed us to calculate the shoot dynamic of the species as a function of soil water availability.Using these data, we compared the behaviour of isolated plants, pairs and trios, and we found below-ground competition to be a fundamental component of global (shoot + root) competition. Finally, our model suggests various circumstances that allow poor competitor plants to coexist in competition for water with more successful competitors. Apparently, this is not only due to transpiration rates, but also to differences in shoot emergence and shoot growth.     

转基因毛白杨外源基因转移的环境风险分析

以8年生转Bt基因败育毛白杨雄株为实验材料,分离其体内、体外、根际土壤、蛀干桑天牛(Apripona germari Hope)排泄物中可培养的细菌和真菌,利用特异引物对获得的微生物进行转Bt基因败育毛白杨雄株外源基因PCR检测.实验发现,381株次细菌中有6株PCR检测阳性;307株次真菌中有4株PCR检测阳性.     

长白山暗针叶林建群种竞争关系的研究

根据野外调查数据,利用Hegyi单木竞争指数模型,定量地研究了长白山暗针叶内主要建群种（以鱼鳞云杉为例）的种内、种间竞争关系,结果表明：暗针叶林中鱼鳞云杉种内竞争强度随着林木径级的增大而迅速减小,也就是说,在暗叶叶林内,鱼鳞云杉种群由于自然调节的作用,随着林木径级的增大,林木因自然稀疏过程导致部分个体死亡,加大了株间距离,因此对光、温、水等生态条件及资源的竞争强度降低,暗针叶林内鱼鳞云杉种内种间竞争强度的顺序为：鱼鳞云杉－鱼鳞云杉＞鱼鳞云杉－臭冷杉＞鱼鳞云杉－红松＞鱼鳞云杉－长白落叶松＞鱼鳞云杉－岳桦＞鱼鳞云杉－杂木,鱼鳞云杉种内种间竞争强度可用幂函数关系CI＝AD－B（其中CI为竞争强度：D为对象木胸径;A、B为参数）表示,并可模拟和预测鱼鳞云杉种内种间竞争强度,从预测结果中发现：当鱼鳞云杉胸径达到35cm后,竞争强度变得小,且变化幅度不大,说明此时该生态系统已基本上达到稳定状态,这可为暗叶林的经营管理提供依据,即在鱼鳞云杉胸径达到35cm之间辅以必要的人工管理措施,以期使得该生态系统尽快达到稳定状态,图2表4参10