Degeneration of sperm reservoir and the loss of mating ability in worker ants

Workers never mate in the large majority of ants, and they have usually lost the spermatheca, an organ specialized for long-term storage of sperm. Such ‘non-sexual’ workers are restricted to laying unfertilized eggs that give rise to males, and they cannot compete with the queens for the production of female offspring. In sharp contrast, workers in 200–300 species from phylogenetically basal subfamilies can reproduce sexually (‘gamergates’) because they retain a functional spermatheca like the queens. Importantly, ‘non-sexual’ workers in closely related species have a vestigial spermatheca. In this study, we compared the reservoir epithelium of ‘sexual’ workers to that of congeneric queens and ‘non-sexual’ workers using 21 species of Amblyoponinae, Ponerinae and Ectatomminae. We show that a pronounced thickening of the epithelium near the opening of the sperm duct is strictly associated with sexual reproduction in both castes. This is unlike ‘non-sexual’ workers in which this epithelium is always very thin, with few organelles; but all other structures remain intact. We discuss this evolutionary degeneration of the spermatheca and how it relates to behavioural or physiological modifications linked to mating. Our results help understand the loss of sexual reproduction by ant workers, a critical step in the extreme specialization of their phenotype.     

Biodiversity below ground: probing the subterranean ant fauna of Amazonia

Ants are abundant, diverse, and ecologically dominant in tropical forests. Subterranean ants in particular are thought to have a significant environmental impact, although difficulties associated with collecting ants underground and examining their ecology and behavior have limited research. In this paper, we present the results of a study of subterranean ant diversity in Amazonian Ecuador that employs a novel probe to facilitate the discovery of species inhabiting the soil horizon. Forty-seven species of ants in 19 genera, including new and apparently rare species, were collected in probes. Approximately 19% of the species collected at different depths in the soil were unique to probe samples. Analysis of similarity (ANOSIM) results showed that the species composition of ants collected with the probe was significantly different from samples collected using other techniques. Additionally, ANOSIM computations indicated the species assemblage of ants collected 12.5 cm below the surface was significantly different from those found at 25, 37.5, and 50 cm. Ant diversity and species accumulation rates decreased with increasing depth. There were no species unique to the lowest depths, suggesting that subterranean ants may not be distributed deep in the soil in Amazonia due to the high water table. The technique we describe could be used to gain new insights into the distribution and biology of subterranean ant species and other members of the species-rich soil invertebrate macrofauna.     

Reproductive disturbance of Japanese bumblebees by the introduced European bumblebee Bombus terrestris

The European bumblebee, Bombus terrestris, is an invasive eusocial species whose distribution is expanding greatly beyond its native range because numerous colonies are imported to or locally produced in non-native countries for pollination of agricultural crops. Closely related species exist in Japan where the unrestricted import and use of B. terrestris has resulted in the establishment of wild colonies. Laboratory studies previously showed that B. terrestris and Japanese native species can copulate and produce fertilized eggs. Although these eggs do not hatch, the interspecific mating can cause a serious reproductive disturbance to native bumblebees. In this study, we determined the frequencies of interspecies mating between B. terrestris males and native bumblebee queens in the wild on the islands of Hokkaido and Honshu by analyzing the DNA sequences of spermatozoa stored in spermathecae of native queens. We found that 20.2% of B. hypocrita hypocrita queens and 30.2% of B. hypocrita sapporoensis queens had spermatozoa of B. terrestris males in their spermathecae. Given that a Bombus queen generally mates only once in her life, such high frequencies of interspecific mating with B. terrestris pose serious threats to the populations of native bumblebees in Japan.     

Hierarchy length in orphaned colonies of the ant <Emphasis Type="Italic">Temnothorax nylanderi</Emphasis>

Workers of the ant Temnothorax nylanderi form dominance orders in orphaned colonies in which only one or a few top-ranking workers begin to produce males from unfertilized eggs. Between one and 11 individuals initiated 80% of all aggression in 14 queenless colonies. As predicted from inclusive fitness models (Molet M, van Baalen M, Monnin T, Insectes Soc 52:247–256, 2005), hierarchy length was found to first increase with colony size and then to level off at larger worker numbers. The frequency and skew of aggression decreased with increasing size, indicating that rank orders are less pronounced in larger colonies.     

Queen regulates biogenic amine level and nestmate recognition in workers of the fire ant, <Emphasis Type="Italic">Solenopsis invicta</Emphasis>

Nestmate recognition is a critical element in social insect organization, providing a means to maintain territoriality and close the colony to parasites and predators. Ants detect the colony chemical label via their antennae and respond to the label mismatch of an intruder with aggressive behavior. In the fire ant, Solenopsis invicta, worker ability to recognize conspecific nonnestmates decreases if the colony queen is removed, such that they do not recognize conspecific nonnestmates as different. Here, we tested the hypothesis that the presence of the colony queen influences the concentration of octopamine, a neuromodulator, in worker ants, which in turn has an effect on nestmate recognition acuity in workers. We demonstrate that queenless workers exhibit reduced brain octopamine levels and reduced discriminatory acuteness; however, feeding queenless workers octopamine restored both. Dopamine levels are influenced by honeybee queen pheromones; however, levels of this biogenic amine were unchanged in our experiments. This is the first demonstration of a link between the presence of the colony queen, a worker biogenic amine, and conspecific nestmate recognition, a powerful expression of colony cohesion and territoriality.     

Costs and benefits of subordinate queens in colonies of the ant,<Emphasis Type="Italic"> Leptothorax gredleri</Emphasis>

Queens of some species of social insects form dominance hierarchies in which only the top-ranking individual reproduces. Such unequal partitioning of reproduction can be stable when subordinate queens increase their inclusive fitness indirectly by helping to rear a related dominant queen's offspring. We investigated whether subordinate queens of the ant, Leptothorax gredleri, affect the reproductive success of the dominant queen. In laboratory colonies with two queens, first eggs were laid approximately 20 days later than in colonies with a single queen, presumably due to aggressive competition among nestmate queens. Nevertheless, two-queen colonies produced on average more brood than one-queen colonies, although egg laying was completely or almost completely monopolized by one single queen. The presence of a subordinate queen therefore appears to increase the productivity of the dominant.     

A life history continuum in the males of a Neotropical ant assemblage: refuting the sperm vessel hypothesis

Animal lifespans range from a few days to many decades, and this life history diversity is especially pronounced in ants. Queens can live for decades. Males, in contrast, are often assumed to act as ephemeral sperm delivery vessels that die after a brief mating flight—a view developed from studies of lekking species in temperate habitats. In a tropical ant assemblage, we found that males can live days to months outside the nest, a trait hypothesized to be associated with female calling, another common mating system. We combined feeding experiments with respirometry to show that lifespan can be enhanced over 3 months by feeding outside the nest. In one focal female calling species, Ectatomma ruidum, feeding enhanced male lifespan, but not sperm content. Extended lifespans outside the nest suggest stronger than expected selection on premating traits of male ants, although the ways these traits shape male mating success remain poorly understood.     

Alternative mating behaviors of the queen polymorphic ant <Emphasis Type="Italic">Temnothorax longispinosus</Emphasis>

Mating behaviors of ants fall into two categories: female calling, in which a female alate releases pheromones that attract males, and male swarming, in which large male aggregations attract females. Female calling is common in species with queens that return to their natal nest to found colonies dependently after mating, while male swarming is common in species with queens that disperse to found independently. In some species that display both founding strategies, a queen-size polymorphism has evolved in which dependent-founding queens are smaller than independent-founding queens. Dependent founding is likely difficult if gynes (virgin queens) are mating in distant swarms. Therefore, a queen may adopt one or the other mating strategy based on its size and founding behavior. We investigated mating behaviors in the queen-polymorphic ant, Temnothorax longispinosus. Observations in laboratory mating arenas indicated that small gynes exhibited significantly lower flight activity than large gynes. Both forms mated in male swarms, and neither form exhibited female calling. The reduced flight activity of the small morph may facilitate returning to the natal nest after mating, provided the mating swarm is located nearby. Therefore, alternative colony-founding behaviors may be possible without the evolution of female-calling behavior; however, the reduced flight activity of small morphs may require that mating swarms are not distant from the natal nest.     

Imperfect chemical female mimicry in males of the ant Cardiocondyla obscurior

Winged and wingless males coexist in the ant Cardiocondyla obscurior. Wingless (“ergatoid”) males never leave their maternal colony and fight remorselessly among each other for the access to emerging females. The peaceful winged males disperse after about 10 days, but beforehand also mate in the nest. In the first 5 days of their life, winged males perform a chemical female mimicry that protects them against attack and even makes them sexually attractive to ergatoid males. When older, the chemical profile of winged males no longer matches that of virgin females; nevertheless, they are still tolerated, which so far has been puzzling. Contrasting this general pattern, we have identified a single aberrant colony in which all winged males were attacked and killed by the ergatoid males. A comparative analysis of the morphology and chemical profile of these untypical attacked winged males and the tolerated males from several normal colonies revealed that normal old males are still performing some chemical mimicry to the virgin queens, though less perfect than in their young ages. The anomalous attacked winged males, on the other hand, had a very different odour to the females. Our study thus exemplifies that the analysis of rare malfunctioning can add valuable insight on functioning under normal conditions and allows the conclusion that older winged males from normal colonies of the ant C. obscurior are guarded through an imperfect chemical female mimicry, still close enough to protect against attacks by the wingless fighters yet dissimilar enough not to elicit their sexual interest.     

Two experimental tests of the relationship between group stability and aggressive conflict in Polistes wasps

Two field experiments were used to examine how the relative benefits of cooperation influence within-group conflict in foundress associations of the paper wasp Polistes dominulus. P. dominulus foundresses can either nest alone or cooperate with other foundresses. We experimentally manipulated the relative benefits of co-foundress associations vs independent reproduction and tested the effect on aggressive within-group conflict. First, we examined aggression between alpha and beta co-foundresses before and after lower-ranking foundresses were removed. Removal of subordinates increases the relative contributions of the remaining subordinates to group reproductive output as there are fewer adults to care for the brood. Transactional models predict that group conflict over reproductive shares will increase as the relative benefits of grouping increase. As predicted, aggression between the co-foundresses significantly increased following subordinate removal. Second, we experimentally reduced ecological constraints on independent nesting by placing a previously orphaned, adoptable nest comb near the occupied nests. Providing an independent breeding opportunity is predicted to increase the benefits of independent reproduction relative to those of cooperating, thereby reducing group stability and aggression. As predicted, aggression between dominant and subordinate foundresses significantly decreased after the orphaned comb was presented. Therefore, group members sense variation in ecological constraints and relative productivity contributions and quickly modulate their behavior in response. Overall, these two experiments suggest that paper wasps behave as if within-group competition is limited by the threat of group dissolution such that stable groups where cooperation is strongly favored can withstand higher levels of conflict than unstable groups.     

鄱阳湖自然保护区生物多样性保护研究

鄱阳湖自然保护区于1983年建立,占地224平方公里.保护区的建立对改善生态环境,保护生物多样性有着重要的意义.20多年来,保护区内生态环境得到明显改善,生物资源不断丰富.为了进一步科学保护区内生物多样性,合理利用资源,针对自然保护区内生物多样性的历史和现状,适当扩大保护区范围,改善当地的经济发展模式等措施,将进一步改善自然保护区的生态环境,保护生物多样性.     

中国城市化对环境空气质量影响的演化规律研究

运用2001-2010年237个地级以上城市的面板数据,共计2353个样本,应用计量经济学分析方法,研究城市化进程中环境空气主要污染物的演化规律.在对面板数据进行平稳性检验后,运用固定效应模型和随机效应模型,将城市空气主要污染物SO2、NO2、PM10的年平均浓度、综合污染指数4个空气质量指标与人均GDP、人口密度、第二产业结构、建成区面积4个反映城市社会经济发展的指标进行回归拟合,得到我国城市经济发展与环境质量变化的关系和演化规律,并提出政策建议.结果表明,2001-2010年,我国城市空气质量与经济发展之间的关系并不完全符合倒U型曲线,不同的污染物类型具有不同的演化规律.10年间,随着城市经济的发展,城市空气中SO2浓度呈现下降的趋势,并到达拐点,符合倒U型曲线;而对于NO2、PM10浓度及综合污染指数,10年间与经济发展之间呈U型关系,即现阶段呈现污染继续加重的态势.此外,城市第二产业结构比例、建成区面积与城市空气主要污染物浓度呈显著的正相关关系.     

The energetic costs of stereotyped behavior in the paper wasp, Polistes dominulus

Polistes wasps engage in many behavioral interactions. Although there has been debate over the meaning of these interactions, these stereotypical behaviors can be used to determine a colony’s linear dominance hierarchy. Due to the implicit relationship between behavioral and reproductive dominance, behavioral interactions are commonly used to distinguish the reproductively dominant alpha foundress from the beta foundress. It has been suggested that in order to maintain reproductive control, the alpha foundress is forced to remain at a physiologically constrained activity limit. This, in turn, may allow aggressive interactions to be used as determinants influencing reproductive partitioning between cooperating individuals. Energetic costs can place important limitations on behavior, but the energetic cost of the interactions has not previously been measured. To address this, we measured the CO₂ production of 19 non-nestmate pairs displaying interactive and noninteractive behavior. The rate of energy used during interaction behavior was positively associated with published rankings of aggression. However, our results indicate that interactions are not very energetically costly in Polistes, particularly when compared to the likely cost of foraging. These data suggest that maintaining reproductive dominance is not very energetically expensive for the dominant and that the dominant foundress expends energy at a lower rate than the subordinate foundress. Electronic Supplementary Material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

污染土壤中重金属的优势流迁移

用亮蓝溶液染色鉴定了2个污染土壤的优势流途径,并分离和采集被染色剂染色和不染色的土样,分析了重金属(Cu,Pb,Cd)含量和形态．结果表明,心土层以下染色部分土壤的重金属含量明显高于不染色部分土壤．两之间的差异随土壤污染程度的增加而增加．染色部分土壤中酸溶态和有机质结合态重金属的比例明显高于不染色部分的土壤．染色部分土壤的细粘粒与粘粒总量的比值也高于非染色部分土壤,但供试土壤的水溶性重金属含量很低,推测颗粒态重金属的迁移是重金属迁移的主要方式,优势流可能在土壤重金属垂直迁移中有重要的作用．     

松嫩平原西部生态脆弱区生态系统服务功能价值的变化

本文在遥感和地理信息系统技术支持下,以1986~2000年的1∶100 000 LandsatTM图像解译数据为基础,全面分析了1986~2000年该区土地利用/覆被的动态变化特征,运用Cost-anza等人对全球生态系统服务价值的计算方法,对松嫩平原西部生态脆弱区土地利用/土地覆被变化(LUCC)引起的生态环境质量变化进行了评估。计算结果表明:在1986~2000年间,由于土地利用面积的变化而使该地区的生态系统的生态价值减少,松嫩平原西部耕地和城乡建设用地有所增加,其他林地、草地、水域和未利用地的面积均减少。耕地面积增加的比例为9.80%、城乡建设用地增加0.66%;林地、草地、水域和未利用地面积减少的比例分别为1.10%、6.80%、1.20%和1.20%,15年的时间里松嫩平原西部生态脆弱区生态系统总价值减少7 000.15×104美元,相当于人民币57 891.24×104元,使生态系统服务价值损失9.74%。     

功夫在大豆及土壤中的残留动态研究

为了制订功夫在大豆上安全使用标准,采用田间试验了研究了功夫在大豆茎叶和土壤中的残留动态,应用ＧＬＣ法测定了功夫在青事,成熟大豆和土壤中的残留量。２年的试验结果表明,功夫在大豆茎叶和土壤中消失较快,其半衰期分别为６．６－７．１ｄ和６．７－１１．６ｄ。施药量为１５ｇ／ｈｍ＾２,施药２次,收获时土壤中的残留量为０．００８ｍｇ／ｋｇ;在青豆和成熟大豆中残留量均低于最低检测浓度。     

实时荧光定量PCR技术对氨氧化细菌的研究

传统的PCR技术只能实现对核酸的定性检测而无法对其进行定量研究。随着分子生物学技术的发展,在传统PCR技术的基础上发展起来的实时荧光定量PCR技术实现了对核酸的定量研究。该技术是向常规PCR反应体系中加入荧光染料或荧光探针,通过监测PCR反应过程中荧光信号的变化来实现对核酸的定量。实时荧光定量PCR技术具有应用范围广、灵敏度高、操作简单、工作量低等特点,在医学和微生物学领域已广泛地应用于疾病诊断、病毒定量检测、微生物群落结构分析及演替规律的研究。文章综述了该项技术的原理、特点及其在环境氨氧化细菌研究中的应用,同时也指出了该技术存在的问题及其发展应用前景。     

祁连山中部素珠链峰地区冰川斑块动态分析

冰川斑块对气候变化的响应不仅表现在冰川长度和面积的变化,而且其格局在斑块数量、形状、平均欧几里德距离、连通度和最大斑块指数等指标上都发生了显著的变化.运用RS和GIS技术对祁连山东段典型地区2001-2009年间冰川斑块动态的分析表明:研究区冰川斑块面积减少了15.39%,面积<1 hm²的小斑块数量消失了50%以上,斑块形状指数在总体和分级层次上都呈减少的趋势,最大斑块的优势降低.由于小斑块消融和大斑块收缩,使斑块间平均欧几里德距离增加了16.56 m.斑块连通度具有尺度依赖性,当在阈限值<7 000 m时,2009年的冰川斑块连通度大于2001年;当阈限值>7 000 m时,趋势相反.7 000~8 000 m之间是尺度特征的转折点.从斑块动态变化来看,冰川斑块动态以消融斑块为主,消融面积为744.30 hm²,占起始面积的16.53%;新生斑块也同时发生,仅增加起始面积的1.15%.但是,消融和新生斑块发生的数量较多,分别为762和367个,冰川单个斑块面积大小与消融面积呈正相关.     

混合堆肥过程中容重的层次效应及动态变化

城市污泥、猪粪混合堆肥表明:升温期和高温期堆体容重分别为0.82g·cm^-3和0.66g·cm^-3,堆体内的氧气仍能满足微生物生长所需;降温期容重为0.58g·cm^-3,通气较充分;腐熟期容重为0.54g·cm^-3,通风充分.升温期和高温期仓门附近堆料的容重具有层次效应,降温期大部分堆料的容重具有层次效应,腐熟期堆体容重的层次效应减弱.升温期堆体中轴线附近、高温期仓内壁附近、降温期整个堆体、腐熟期仓门和中轴线附近,堆体深度对容重具有显著影响.升温期和腐熟期,仓门对容重产生显著影响.各堆肥期堆体的容重随深度的增加而呈增大的趋势,容重与堆肥时间满足二级动力学方程.     

潮河流域降雨径流事件污染物输出特征

在半干旱半湿润地区,非点源养分污染的发生主要由降水径流事件驱动,伴随这些短暂脉冲事件流失的养分量决定着一年总的污染排放负荷,因此研究汛期降雨径流事件下水体污染动态特征是半干旱半湿润地区污染负荷模拟及控制的关键.以北京市密云水库上游的潮河流域为研究区域,2018年和2019年汛期进行古北口站和下会站的降雨径流过程水质水量...