Nest inheritance is the missing source of direct fitness in a primitively eusocial insect

Animals that cooperate with nonrelatives represent a challenge to inclusive fitness theory, unless cooperative behavior is shown to provide direct fitness benefits. Inheritance of breeding resources could provide such benefits, but this route to cooperation has been little investigated in the social insects. We show that nest inheritance can explain the presence of unrelated helpers in a classic social insect model, the primitively eusocial wasp Polistes dominulus. We found that subordinate helpers produced more direct offspring than lone breeders, some while still subordinate but most after inheriting the dominant position. Thus, while indirect fitness obtained through helping relatives has been the dominant paradigm for understanding eusociality in insects, direct fitness is vital to explain cooperation in P. dominulus.     

Wasp gene expression supports an evolutionary link between maternal behavior and eusociality

The presence of workers that forgo reproduction and care for their siblings is a defining feature of eusociality and a major challenge for evolutionary theory. It has been proposed that worker behavior evolved from maternal care behavior. We explored this idea by studying gene expression in the primitively eusocial wasp Polistes metricus. Because little genomic information existed for this species, we used 454 sequencing to generate 391,157 brain complementary DNA reads, resulting in robust hits to 3017 genes from the honey bee genome, from which we identified and assayed orthologs of 32 honey bee behaviorally related genes. Wasp brain gene expression in workers was more similar to that in foundresses, which show maternal care, than to that in queens and gynes, which do not. Insulin-related genes were among the differentially regulated genes, suggesting that the evolution of eusociality involved major nutritional and reproductive pathways.     

Sex-linked genetic influence on caste determination in a termite

The most ecologically successful and destructive termite species are those with both a nymph caste and an irreversibly wingless worker caste. The early developmental bifurcation separating these castes is widely accepted to be strictly environmentally determined. We present evidence that genotype also influences this process. Offspring from four different crosses of nymph- and worker-derived secondary reproductive individuals had strongly differentiated caste and sex ratios, despite uniform rearing conditions. These data fit an X-linked, one-locus-two-allele model. Of five possible genotypes, one was lethal, two resulted in workers, and two resulted in either nymphs or environmentally determined workers. Caste is thus controlled both by environment and by a complex genetic inheritance pattern.     

The sociogenesis of insect colonies

Studies on the social insects (ants, bees, wasps, and termites) have focused increasingly on sociogenesis, the process by which colony members undergo changes in caste, behavior, and physical location incident to colonial development. Caste is determined in individuals largely by environmental cues that trigger a sequence of progressive physiological restrictions. Individual determination, which is socially mediated, yields an age-size frequency distribution of the worker population that enhances survival and reproduction of the colony as a whole, typically at the expense of individuals. This "adaptive demography" varies in a predictable manner according to the species and size of the colony. The demography is richly augmented by behavioral pacemaking on the part of certain castes and programmed changes in the physical position of colony members according to age and size. Much of what has been observed in these three colony-level traits (adaptive demography, pacemaking, and positional effects) can be interpreted as the product of ritualization of dominance and other forms of selfish behavior that is still found in the more primitive insect societies. Some of the processes can also be usefully compared with morphogenesis at the levels of cells and tissues.     

Specialized face learning is associated with individual recognition in paper wasps

We demonstrate that the evolution of facial recognition in wasps is associated with specialized face-learning abilities. Polistes fuscatus can differentiate among normal wasp face images more rapidly and accurately than nonface images or manipulated faces. A close relative lacking facial recognition, Polistes metricus, however, lacks specialized face learning. Similar specializations for face learning are found in primates and other mammals, although P. fuscatus represents an independent evolution of specialization. Convergence toward face specialization in distant taxa as well as divergence among closely related taxa with different recognition behavior suggests that specialized cognition is surprisingly labile and may be adaptively shaped by species-specific selective pressures such as face recognition.     

Ancestral monogamy shows kin selection is key to the evolution of eusociality

Close relatedness has long been considered crucial to the evolution of eusociality. However, it has recently been suggested that close relatedness may be a consequence, rather than a cause, of eusociality. We tested this idea with a comparative analysis of female mating frequencies in 267 species of eusocial bees, wasps, and ants. We found that mating with a single male, which maximizes relatedness, is ancestral for all eight independent eusocial lineages that we investigated. Mating with multiple males is always derived. Furthermore, we found that high polyandry (>2 effective mates) occurs only in lineages whose workers have lost reproductive totipotency. These results provide the first evidence that monogamy was critical in the evolution of eusociality, strongly supporting the prediction of inclusive fitness theory.     

Caste in a primitive ant: absence of age polyethism in amblyopone

Polyethism, the divison of labor among members of a colony, is based on worker age and size in ants. In the ponerine species Amblyopone pallipes worker behavior is independent of age, therefore temporal castes, or groups of age-related task specialists, do not exist. This primitive caste system, previously unknown in ants, appears to be correlated with the peculiar characteristics of the life history and ecology of Amblyopone.     

Evolution of the gene network underlying wing polyphenism in ants

Wing polyphenism in ants evolved once, 125 million years ago, and has been a key to their amazing evolutionary success. We characterized the expression of several genes within the network underlying the wing primordia of reproductive (winged) and sterile (wingless) ant castes. We show that the expression of several genes within the network is conserved in the winged castes of four ant species, whereas points of interruption within the network in the wingless castes are evolutionarily labile. The simultaneous evolutionary lability and conservation of the network underlying wing development in ants may have played an important role in the morphological diversification of this group and may be a general feature of polyphenic development and evolution in plants and animals.     

Chemical Usurpation of a Nest by Paper Wasp Parasites

The paper wasp Polistes atrimandibularis is an obligatory social parasite of another Polistes species, P. biglumis bimaculatus. To control the host nest, the parasite sequentially changes the composition of its chemical signature, the cuticular hydrocarbons, during the colonial cycle. Gas chromatography-mass spectrometry of the cuticular hydrocarbons at every stage of the cycle showed that the parasite can switch on and off an entire chemical family, namely, the unsaturated hydrocarbons. In this way the parasite can match the host signature at a critical moment of the colonial cycle.     

蜜蜂（Apis mellifera L.）幼虫级型分化差异蛋白质组分析

【目的】对蜜蜂（Apis mellifera L.）蜂王与工蜂级型分化期的蛋白质组进行比较,以探明蜂王和工蜂在级型分化时期蛋白质表达调控方面的异同。【方法】采用双向电泳建立蜂王和工蜂级型分化期蛋白质组表达 谱,获得图谱中蛋白质表达的数量、表达量、等电点和分子量等信息,然后进行比较蛋白质组研究。【结果】在幼虫3日龄,蜂王表达288个蛋白质,工蜂表达259个蛋白质,2种级型蜂共有蛋白质为156个,其中25个蛋白质在蜂王中的表达量显著大于（P＜0.05）工蜂,34个蛋白质工蜂表达量显著大于（P＜0.05）蜂王,而蜂王和工蜂的特异蛋白质分别为132个和103个;到幼虫5日龄时,蜂王表达274个蛋白质,工蜂为236个,这2种级型蜂共有蛋白质点为95个,其中蜂王15个蛋白质的表达量显著大于（P＜0.05）工蜂,工蜂26个蛋白质的表达量显著大于（P＜0.05）蜂王,而蜂王特异蛋白质点为179个,工蜂特异蛋白质点为141个;到蛹11日龄时,蜂王蛋白质组有311个蛋白质点,而工蜂则有278个蛋白质点,2种蜂共有蛋白质点为194个,其中蜂王45个蛋白质的表达量显著大于（P＜0.05）工蜂,工蜂35个蛋白质的表达量显著大于（P＜0.05）蜂王,而蜂王的特异蛋白质点为117个,工蜂特异蛋白质点为84个。【结论】在蜜蜂3日龄、5日龄、11日龄时,蜂王和工蜂的蛋白质表达谱存在显著差异,蜂王表达的蛋白质总数和特有蛋白质数都较工蜂多,说明蜂王幼虫的基因表达和代谢比工蜂幼虫更加旺盛。2种级型蜂发育中所表达的共有蛋白质可能是它们发育所必须的管家蛋白质,但级型间部分共有蛋白质的表达模式存在较大差异,在3个日龄中蜂王和工蜂中所表达的特异蛋白质表明在级型分化中,不同级型需要不同的蛋白质来调节各自的发育。这些特异蛋白质是否是级型发育相关的功能蛋白质,还有待进一步的研究。     

从《摩奴法典》看古印度的种姓制度

《摩奴法典》是印度最古老的宗教、哲学与法律的汇编,由婆罗门教僧侣根据吠陀经典和历来的习惯编制而成,维护种姓制度是法典的核心内容。随着印度教的发展,种姓制度涵盖和渗透了印度社会人与人之间在政治、经济、社会生活等各方面的相互关系,在印度国内外产生了重要影响,一直持续到今天,要想消除它任重而道远。     

Ancestral developmental potential facilitates parallel evolution in ants

Complex worker caste systems have contributed to the evolutionary success of advanced ant societies; however, little is known about the developmental processes underlying their origin and evolution. We combined hormonal manipulation, gene expression, and phylogenetic analyses with field observations to understand how novel worker subcastes evolve. We uncovered an ancestral developmental potential to produce a "supersoldier" subcaste that has been actualized at least two times independently in the hyperdiverse ant genus Pheidole. This potential has been retained and can be environmentally induced throughout the genus. Therefore, the retention and induction of this potential have facilitated the parallel evolution of supersoldiers through a process known as genetic accommodation. The recurrent induction of ancestral developmental potential may facilitate the adaptive and parallel evolution of phenotypes.     

Genetic relatedness in colonies of tropical wasps with multiple queens

The evolution of worker behavior in the social insects is usually explained by kin selection: although workers do not produce offspring, they do reproduce their genes by aiding the reproduction of relatives. The most difficult case for kin selection theory would be species in which workers are fully capable of reproducing but instead opt to rear brood of low relatedness. These conditions are perhaps best fulfilled by the swarm-founding wasps because they have little caste differentiation and their colonies usually have multiple queens, which should lower relatedness. Estimates of within-colony relatedness for three species in this group confirm that it is sometimes (but not always) very low. Inbreeding is negligible in these species, so the hypothesis that inbreeding may raise relatedness is not supported. The maintenance of worker behavior in such species is a significant challenge for kin selection theory.     

Territorial strategies in ants

Several features in social insects, particularly in ants, make the behavioral organization of territoriality considerably more complex than that of solitary animals. The establishment and maintenance of territories are based on a division of labor and a complex communication system. The analyses of territorial strategies in ants comprise the study of the design and spatiotemporal structure of the territory, as well as the social mechanisms through which the insect society pursues its territorial strategy. The geometric and behavioral organization of the absolute territories of the African weaver ants (Oecophylla longinoda) and harvester ants (Pogonomyrmex), and of the "spatiotemporal territories" of honey ants (Myrmecocystus mimicus) are described, and simple cost-benefit models are developed to illustrate the economic defensibility of each type of territory.     

Social insect networks

Social insect colonies have many of the properties of adaptive networks. The simple rules governing how local interactions among individuals translate into group behaviors are found across social groups, giving social insects the potential to have a profound impact on our understanding of the interplay between network dynamics and social evolution.     

Sex Ratio of Parental Investment in Colonies of the Social Wasp Polistes fuscatus

Field estimates of parental investment in the two sexes in the social paper wasp Polistes fuscatus indicate that the mother's interests, rather than those of her worker offspring, are realized. Local competition for mates seemed to be absent, and the population investment ratio was not significantly different from 1:1. Workers are not more closely related to the brood they tend than they would be to their own offspring. The 3/4 relationship between sisters in haplodiploid species cannot account for the maintenance of eusociality in this case.     

Social wasps: discrimination between kin and nonkin brood

In experiments in which nest boxes were switched, colony foundresses of the social wasp Polistes fuscatus accepted sisters' combs with little brood destruction but destroyed younger brood in the combs of less closely related females and sometimes deserted these combs. Discrimination between related and unrelated brood does not appear to depend on prior brood contact or environmentally acquired cues.     

Arabidopsis, the Rosetta stone of flowering time?

Multiple environmental and endogenous inputs regulate when plants flower. The molecular genetic dissection of flowering time control in Arabidopsis has identified an integrated network of pathways that quantitatively control the timing of this developmental switch. This framework provides the basis to understand the evolution of different reproductive strategies and how floral pathways interact through seasonal progression.     

昆虫分类在分子水平上的研究进展

昆虫分类是研究昆虫物种之间差异的基础,是研究昆虫进化的必要手段。近年来,随着分子生物技术的飞速发展,昆虫分类在分子水平上的研究也取得了很大的进步。主要从遗传学、生物化学及分子生物学层面分析归纳了昆虫分类技术在分子水平上的研究进展。     

6种家禽孤束核的脊髓通路：HRP逆行追踪法研究

应用微电泳逆行追踪技术，分别向北京鸭，麻鸭，鹅、鸡、鸽和鹌鹑脊髓的颈、胸、腰段的一侧灰质中导入辣根过氧化物酶系统地研究了其孤束核至脊髓传导通路和细胞构筑。结果如下：在颈髓不同节段单侧灰质导入Ｈ ＲＰ后，６种家禽延髓的双侧孤束核内都出现了大量的标准细胞；