Courting virtual rivals increase ejaculate size in sticklebacks (<Emphasis Type="Italic">Gasterosteus aculeatus</Emphasis>)

Sperm competition occurs when sperm of two or more males compete to fertilize a given set of eggs. Game-theory models of sperm competition predict that males, which face an increased risk of sperm competition, will invest more sperm in a mating. In the pair-spawning three-spined stickleback ( Gasterosteus aculeatus), males attempt to steal fertilizations (i.e. to sneak) when they are in the courting phase, but not when they are parental. The behaviour of neighbouring males may therefore indicate the risk of sperm competition. We visually confronted males before spawning with computer animations of the same virtual stickleback showing two different behaviours: either courting (high risk of sperm competition) or brood-caring (low risk of sperm competition). We show that males invest significantly more sperm (absolutely and relatively with respect to available sperm in the testes) after the courting stimulus. The relative investment ratio between the courting and the brood-caring treatment was on average 1.75. Three-spined sticklebacks thus seem to assess the risk of sperm competition by the behaviour of neighbours and to adjust their ejaculate accordingly. This result suggests that the evolutionary force of sperm competition has led to precise mechanisms of future risk assessment.     

大鼠类Alu重复序列的克隆及其在染色体DNA突变分析中的应用

从大鼠低Ｃｏｔ值ＤＮＡ文库分离到一种类Ａｌｕ的重复序列,命名为ＲＡＬＲＳ－１。对ＲＡＬＲＳ－１克隆并进行了测序,长度为２８３ｂｐ,发现其中含有单一的微卫星（ｍｉｃｒｏｓａｔｅｌｌｉｔｅ）序列ＡＧ,ＡＧＧ和ＡＧＧＧ。ＲＡＬＲＳ－１ＤＮＡ序列在大鼠单倍体基因组中的拷贝数为１５００００～３３００００。依ＲＡＬＲＳ－１中的一段序列合成了一２８寡核苷酸探针（ＡＧＧＧ）７,对大鼠正常组织和肿瘤组织ＤＮＡ指数谱     

A cognitive approach to the post-Soviet Central Asian pasture puzzle: new data from Kyrgyzstan

Regional Environmental Change - Despite internationally recognized definitions, there remains debate over what constitutes ‘actual’ degradation in various agro-pastoral contexts. This...     

Vulnerability of Catalan (NW Mediterranean) ports to wave overtopping due to different scenarios of sea level rise

The overtopping of port breakwaters may affect the assets located at the breakwater lee side. If adaptation measures are not taken, the sea level rise will increase the overtopping discharges putting those assets at significant risk. This study compares, at a regional scale, overtopping discharges over port breakwaters for three storm conditions (return periods of 1, 5 and 50 years) under present climate as well as for three scenarios of sea level rise based on recent projections. The results indicate that, for the worst storm and sea level rise conditions, the overtopping discharge would not be negligible (larger than 1 l/s/m) in 35 ports (84 %), in contrast to only 18 ports (42 %) being affected under present conditions. In addition, in 28 ports (65 %) the overtopping would be at least one order of magnitude larger than for present conditions. In the case of large storms, in 2 ports the overtopping discharge exceeds 200 l/s/m (the discharge that can initiate breakwater damage) under present conditions, while in the worst scenario of sea level rise the number of ports exceeding this value would be 7. On the other hand, the vulnerability of each port for which overtopping flow is greater than an acceptable discharge flux is assessed, and regional maps of vulnerability are plotted. For the worst storm conditions, 23 % of the Catalan ports have risks associated with overtopping under present climate conditions. This percentage would increase to 47 % in the worst sea level rise scenario.     

河岸蜘蛛——多样水生生态系统中PCB污染的指示生物

栖息在河岸的蜘蛛越来越多地被用来追踪水生生态系统中存在和流出污染物的空间格局。然而,我们对蜘蛛在何种情况下可有效标志水生污染的认识有限。本研究力证在具有高生境异质性的水生生态系统中,能够有效地利用河岸蜘蛛来追踪沉积物中多氯联苯(PCBs)污染的空间格局。2011年到2013年,在五大湖共同关注区(AOC)的Manistique河流域,对2类常见科属的河岸蜘蛛进行采样,结果表明生物体内的ΣPCB浓度的空间格局能够普遍地追踪采样点范围内沉积物中ΣPCBs的空间变化。该研究区域位于密歇根北部半岛南岸(Manistique,MI,US),是一个河口生态系统,包括港口、河流、回水和湖泊等栖息地。沉积物ΣPCB浓度用总有机碳浓度进行归一,解释了11个采样点中41%的以脂类归一的蜘蛛ΣPCB浓度变异。此外,2类常见河岸蜘蛛类群(园蛛科Araneidae和长脚蛛科Tetragnathidae)的ΣPCB浓度高度相关(r² > 0.78),并且按全年计算其平均ΣPCB浓度两者相似。结果表明,在异质性的水生生态系统中,例如在河流入海口,会因为栖息地和污染物变化在水生生物分类中的差别不明显,河岸蜘蛛就可能成为水生和河岸食物网中PCB有效性的标记物。此外,对于为不同种群大型结网蜘蛛提供生存条件的海岸线开发和沿岸植被的生境异质性,目前的方法具有很强的适用性。
精选自Kraus, J. M., Gibson, P. P., Walters, D. M. and Mills, M. A. (2017), Riparian spiders as sentinels of polychlorinated biphenyl contamination across heterogeneous aquatic ecosystems. Environmental Toxicology and Chemistry, 36: 1278–1286. doi: 10.1002/etc.3658
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3658/full
     

Social networks and the cognitive motivation to realize network opportunities: a study of managers' information gathering behaviors

Information gathering is central to a variety of organizational behavior theories, but researchers have suggested that our understanding of the actual information gathering behaviors of managers is underdeveloped. Social network characteristics are theorized to be a key determinant of information gathering behaviors, but social network research has been criticized for: (1) not measuring the intervening mechanisms by which network characteristics are theorized to have their effects and (2) not considering how actors' motivation affects what network benefits are realized. This article addresses these concerns through an empirical study of the actual information gathering behaviors of managers. It posits that individual differences in a personality variable called need for cognition capture differences in actors' cognitive motivation to realize the potential information benefits that exist in their social networks. Results show that network characteristics do affect information benefits, but these effects are stronger for managers motivated to take advantage of them. These findings both support social capital theory and suggest the important role that personality can play in augmenting social network analyses. Copyright © 2007 John Wiley & Sons, Ltd.     

Assessment of environmental estrogens and the intersex/sex reversal capacity for chinook salmon (Oncorhynchus tshawytscha) in primary and final municipal wastewater effluents

A trickling filter/solid contact (TF/SC) biological secondary treatment plant with chlorine disinfection serving a suburban population of 740,000 was assessed for environmental estrogens. Weekly grab samples were taken at established sampling points and analyzed for various pertinent environmental estrogens including industrial chemicals, and natural and synthetic steroidal estrogens. Additionally, human estrogen receptor (hER) activity and capacity to elicit intersex/sex reversal for the wastewater was monitored using a recombinant yeast assay and whole fish exposures, respectively. hER activity levels varied from 76 to 106 ng/L E2 equivalents in the primary effluent, and were reduced by 25% by biological treatment. For the primary and final effluent no evidence of sex reversal or intersex was apparent in any of the treatment groups (1%, 3%, 10%, or 100%) based on genetic sex determinations and histological examination of the gonads in alevin from 28 d exposed chinook salmon (Oncorhynchus tshawytscha) eggs.