Permanent loss of wings in queens of the ant <Emphasis Type="Italic">Odontomachus coquereli</Emphasis> from Madagascar

Winged queens are the most common reproductives in ants. They are morphologically specialized for independent colony foundation, with wings for long-range dispersal and metabolic reserves to raise the first brood. However independent foundation can sometimes be selected against and replaced by fission, featuring short-range dispersal on the ground and reproductives that are dependent on the wingless workers for all non-reproductive tasks. We investigated the evolutionary consequences of this transition on the morphology of the reproductives by collecting 30 colonies of Odontomachus coquereli from Madagascar, the only species in the genus where winged queens have never been found. Data about colony demography, morphometry, allometry and ovarian dissections showed that the winged queen caste has been replaced by a wingless reproductive caste with distinct body proportions relative to the workers or to congeneric winged queens. The 17 reproductives that we measured exhibited little size variability. A single wingless reproductive was found in each colony, corresponding to ‘ergatoids’ in literature. Several facts suggest that colonies reproduce by fission, notably the relatively constant colony size (19±11 workers). The developmental origins of wingless reproductive phenotypes need investigation; little genetic change may be involved, as seen when Odontomachus larvae are parasitized by nematodes. The sole function of wingless reproductives in O. coquereli is reproduction, and they contrast with multi-purpose wingless reproductives found in other ants, where numerous intermorphs occur in each colony and contribute to sterile tasks. Received 15 December 2006; revised 26 February 2007; accepted 1 March 2007.     

Plasticity and epistasis strongly affect bacterial fitness after losing multiple metabolic genes

Many bacterial lineages lack seemingly essential metabolic genes. Previous work suggested selective benefits could drive the loss of biosynthetic functions from bacterial genomes when the corresponding metabolites are sufficiently available in the environment. However, the factors that govern this “genome streamlining” remain poorly understood. Here we determine the effect of plasticity and epistasis on the fitness of Escherichia coli genotypes from whose genome biosynthetic genes for one, two, or three different amino acids have been deleted. Competitive fitness experiments between auxotrophic mutants and prototrophic wild‐type cells in one of two carbon environments revealed that plasticity and epistasis strongly affected the mutants’ fitness individually and interactively. Positive and negative epistatic interactions were prevalent, yet on average cancelled each other out. Moreover, epistasis correlated negatively with the expected effects of combined auxotrophy‐causing mutations, thus producing a pattern of diminishing returns. Moreover, computationally analyzing 1,432 eubacterial metabolic networks revealed that most pairs of auxotrophies co‐occurred significantly more often than expected by chance, suggesting epistatic interactions and/or environmental factors favored these combinations. Our results demonstrate that both the genetic background and environmental conditions determine the adaptive value of a loss‐of‐biochemical‐function mutation and that fitness gains decelerate, as more biochemical functions are lost.     

Breeding system and reproductive skew in a highly polygynous ant population

Factors affecting relatedness among nest members in ant colonies with high queen number are still poorly understood. In order to identify the major determinants of nest kin structure, we conducted a detailed analysis of the breeding system of the ant Formica exsecta. We estimated the number of mature queens by mark-release-recapture in 29 nests and dissected a sub-sample of queens to assess their reproductive status. We also used microsatellites to estimate relatedness within and between all classes of nestmates (queens, their mates, worker brood, queen brood and male brood). Queen number was very high, with an arithmetic mean of 253 per nest. Most queens (90%) were reproductively active, consistent with the genetic analyses revealing that there was only a minimal reproductive skew among nestmate queens. Despite the high queen number and low reproductive skew, almost all classes of individuals were significantly related to each other. Interestingly, the number of resident queens was a poor predictor of kin structure at the nest level, consistent with the observation that new queens are produced in bursts leading to highly fluctuating queen number across years. Queen number also varied tremendously across nests, with estimates ranging from five to several hundred queens. Accordingly, the harmonic mean queen number (40.5) was six times lower than the arithmetic mean. The variation in queen number was the most important factor of the breeding system contributing to a significant relatedness between almost all classes of nestmates despite a high average number of queens per nest. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Received 12 November 2007; revised 4 May 2008; accepted 8 May 2008.     

Seasonal cycle of colony structure in the Ponerine ant Pachycondyla chinensis in western Japan (Hymenoptera, Formicidae)

Investigation of reproductive strategies of ants in the subfamily Ponerinae is important for understanding of the evolution of social structure and of the significance of caste dimorphisms. The biology of species with mated and egg-laying workers (gamergates) has been studied for many species, however, little attention has been paid to species that reproduce via alate queens only. We investigated the seasonal cycle of changes in the colony structure of Pachycondyla chinensis reproduced by alate queens in western Japan, and found the following novel biological characteristics of this species. P. chinensis showed a remarkable caste dimorphism in ovariole numbers: workers had no ovaries while queens had 18 to 36 ovarioles in their ovaries. The nesting system seemed to be polydomous: 266 of 400 nests collected were queenless. The number of queenless nests increased during the reproductive season. Among the 134 queenright nests, 38 had several mated-queens without significant differences in ovary activation and the remaining 96 nests were monogynous. During winter to early spring, most nests were polygynous. After alate production, most of the old queens seemed to die or be expelled and replaced by new queens. Virgin dealated queens were often found and they seemed to have laid eggs. Received 3 August 2007; revised 19 December 2007; accepted 20 December 2007     

羽化和性成熟时中华蜜蜂蜂王和雄蜂转录组分析

【目的】为了系统了解中华蜜蜂Apis cerana cerana蜂王和雄蜂转录组特征,丰富蜜蜂转录组数据信息。【方法】本研究利用高通量测序的方法分别检测中华蜜蜂蜂王和雄蜂刚出房、性成熟时期以及性成熟期蜂王生殖系统和雄蜂生殖系统之间转录组表达差异。【结果】经过测序获得质量值不低于20的碱基比例（Q20）均高于90%;所有reads组装成90 839个unigenes,平均长度1 549 bp;基于5个数据库(NR,Swiss Prot,GO,COG和KEGG)进行比对,共有45 112个unigenes被注释。差异基因表达分析发现,与刚出房时相比,性成熟的蜂王和雄蜂均在表皮蛋白、细胞色素P450、气味结合蛋白等家族基因上存在显著差异表达,而且这些差异表达基因与蜜蜂生长发育和性成熟过程中蜜蜂骨骼发育、生殖系统发育、嗅觉发育等方面有关;性成熟蜂王与性成熟雄蜂之间以及它们生殖系统之间在气味结合蛋白基因方面存在显著差异。【结论】结果表明,中华蜜蜂在性成熟过程中,体内大量基因的表达发生了变化。这些结果揭示了中华蜜蜂性成熟发育的整体基因表达特征,在得到大量转录组unigene序列的同时,获得了一批与蜜蜂性成熟有关的基因序列,为深入开展中华蜜蜂生长发育与繁殖研究提供了丰富的数据资源。     

Honeybee viruses in Uruguay

Mortality of honeybees is a serious problem that beekeepers have to face periodically in Uruguay and worldwide. The presence of RNA viruses, in addition to other pathogens may be one of its possible causes. In this work, we detected Chronic bee paralysis virus, Acute bee paralysis virus, Black queen cell virus, Sacbrood virus and Deformed wing virus in samples of Uruguayan honeybees with or without Varroa destructor and Nosema apis. The detection of viruses in different provinces, simultaneous co-infection of colonies by several viruses and the fact that 96% of the samples were infected with one or more virus, indicates they are widely spread in the region.     

蜜蜂蜂王信息素研究进展

综述了蜂王信息素的化学组成、特性、作用 ,以及与幼虫信息相互关系的研究进展 ,对蜂王信息素在养蜂和植物授粉中的应用做了介绍。西方蜜蜂的蜂王上颚腺信息素 (queen’smandibularglandpheromone,QMP)。QMP包含了 5种成分 :(E) -9-氧 -2 -癸烯酸 ( 9 ODA)、(R ,E) ( ) 和 (S,E) ( +) 9 羟基 -2 -癸烯酸 ( -9 HDA和 +9 HDA)、甲基p -羟基安息香酸盐 (HOB)、4-羟基 -3 -甲氧苯乙醇 (也称香草醇 ,HVA) ,9 ODA是其中最重要的成分 ;QMP的组分与蜜蜂的进化程度有关 ,进化程度越高则组分越复杂 ;QMP通过抑制保幼激素的产生来调节青年工蜂的个体发育。     

Workers of the primitively eusocial wasp <Emphasis Type="Italic">Ropalidia marginata</Emphasis> do not perceive their queen across a wire mesh partition

Queens of primitively eusocial wasps generally have active and behaviourally dominant queens who use physical aggression to suppress worker reproduction. Although a Ropalidia marginata queen is strikingly docile and behaviourally non-dominant, she is completely successful in maintaining reproductive monopoly. R. marginata queens must achieve such reproductive monopoly by some means other than overt physical aggression. Upon loss or removal of the queen, one of the workers (referred to as the potential queen) becomes extremely aggressive and will eventually go on to become the next queen of the colony, if the original queen is not returned. The fact that potential queens are not discernible in the presence of the queen but become obvious within minutes after removal of the queen raises the question of how workers in general and the potential queens in particular, perceive the presence or absence of their queens. Here, we have conducted experiments in which we separate half of the workers from their queen by a wire mesh screen and study their behavioural response to such separation. We demonstrate that the presence of the queen is not perceived across the wire mesh screen, which suggests that if the queen uses a pheromone to signal her presence, then that pheromone is not very volatile.     

We know that the wasps 'know': cryptic successors to the queen in Ropalidia marginata

Unlike other primitively eusocial wasps, Ropalidia marginata colonies are usually headed by remarkably docile and behaviourally non-dominant queens who are nevertheless completely successful in maintaining reproductive monopoly. As in other species, loss of the queen results in one of the workers taking over as the next queen. But unlike in other species, here, the queen's successor cannot be predicted on the basis of dominance rank, other behaviours, age, body size or even ovarian development, in the presence of the former queen. But the swiftness with which one and only one individual becomes evident as the potential queen led us to suspect that there might be a designated successor to the queen known to the wasps, even though we cannot identify her in the queen's presence. Here, we present the results of experiments that support such a 'cryptic successor' hypothesis, and thereby lend credence to the idea that queen (and potential queen) pheromones act as honest signals of their fertility, in R. marginata.     

Parasite transmission among relatives halts Red Queen dynamics

The theory that coevolving hosts and parasites create a fluctuating selective environment for one another (i.e., produce Red Queen dynamics) has deep roots in evolutionary biology; yet empirical evidence for Red Queen dynamics remains scarce. Fluctuating coevolutionary dynamics underpin the Red Queen hypothesis for the evolution of sex, as well as hypotheses explaining the persistence of genetic variation under sexual selection, local parasite adaptation, the evolution of mutation rate, and the evolution of nonrandom mating. Coevolutionary models that exhibit Red Queen dynamics typically assume that hosts and parasites encounter one another randomly. However, if related individuals aggregate into family groups or are clustered spatially, related hosts will be more likely to encounter parasites transmitted by genetically similar individuals. Using a model that incorporates familial parasite transmission, we show that a slight degree of familial parasite transmission is sufficient to halt coevolutionary fluctuations. Our results predict that evidence for Red Queen dynamics, and its evolutionary consequences, are most likely to be found in biological systems in which hosts and parasites mix mainly at random, and are less likely to be found in systems with familial aggregation. This presents a challenge to the Red Queen hypothesis and other hypotheses that depend on coevolutionary cycling.