Interpopulational differences in chemical composition and chemosensory recognition of femoral gland secretions of male lizards Podarcis hispanica: implications for sexual isolation in a species complex

Summary. Molecular studies suggest that the Iberian wall lizard, Podarcis hispanica, forms a species complex with several monophyletic types. In Central Spain two of these types are spatially not isolated and may interact. Sex pheromones are important for species recognition and, thus, differences between lizards’ types in chemicals used in intraspecific communication could lead to reproductive isolation. Analyses by GC-MS showed that the femoral gland secretions of adult males of different types were different. Males of one type had twelve exclusive compounds, and proportions of some shared compounds differed. This presumably would reflect selection for the persistency and efficiency of chemical signals in different environments; less volatile compounds and with a higher chemical stability being favoured in the type of lizards inhabiting more humid climatic conditions. Differential tongue-flick rates to scents from femoral secretions indicated that males were able to detect and discriminate between males of different types based on chemical cues alone. In contrast, females detected but did not seem able to discriminate between scents of the two types of males. Thus, multiple factors might be simultaneously acting either against or in favor of speciation, leading, on the one hand, to genetic differences between types, but, on the other hand, probably precluding an effective reproductive isolation in areas where both types of lizards may interact.     

Food influence on colonial recognition and chemical signature between nestmates in the fungus-growing ant <Emphasis Type="Italic">Acromyrmex subterraneus subterraneus</Emphasis>

Summary. Neotropical Fungus-growing leaf-cutting ants (tribe Attini) live in obligatory symbiosis with a fungus, which they grow on fresh leaves harvested by workers. Colonial recognition is likely based on chemical cues provided by cuticular hydrocarbons that have been found to be partly influenced by environmental odor sources. The diet breadth of Acromyrmex subterraneus subterraneus enabled us to test the impact of different plant diets on colonial recognition. The intermediary of the fungus in the ants feeding habit adds a special angle to the question. From a queenright (QR) mother colony of A. s. subterraneus we formed several groups of queenless (QL) workers with fungus (approx. 700 ants). The QR colony and two of the QL-groups were fed with the same diet of fresh bramble leaves. Two other QL-groups were fed with privet leaves and two with rose flowers. After 4 months, QR workers were significantly more aggressive towards the QL-group fed with rose flowers or privet leaves than towards workers of the QL-groups fed with fresh bramble leaves. Rose-fed QL workers were aggressive towards privet-fed QL workers and vice versa, but never towards workers of their counterpart group that fed on the same diet. These results suggest that the absence of the queen or the separation time between groups played a minor role in shaping nestmate recognition cues as compared to the diet. The behavioral studies were supplemented by chemical analyses of cuticles, postpharyngeal glands (PPG) and plant-food extracts revealing profiles variations that were correlated with the dietary changes. However, although the plant extract contained several hydrocarbons there was no congruency between the plant profile and the respective diet-group ants. These results support the hypothesis that the diet influences indirectly the chemical profiles and consequently the recognition cues in A. s. subterraneus.     

Hibernation clustering and its consequences for associative nest foundation in<Emphasis Type="Italic"> Polistes dominulus</Emphasis> (Hymenoptera Vespidae)

Various studies indicate that cuticular hydrocarbons (CHCs) act as cues for nestmate recognition in paper wasps and other social insects. A recent study showed that associative nest foundation in Polistes dominulus is mainly performed by foundresses coming from the same locality. In the present study, we induced future foundresses of P. dominulus collected in two different localities to hibernate in the laboratory in aggregates of individuals from the same or different localities. After 2 months of hibernation, foundresses from different localities but from the same experimental cluster did not show any preference to associate, at the time of nest foundation, with individuals coming from the same original locality. The cuticular chemical profiles of individuals from the mixed hibernation clusters were quite similar and significantly different from those of individuals which hibernated with other foundresses from the same locality. These findings suggest that, in this species, mechanisms other than nestmate chemical recognition play a major role in the spring association of gynes during the foundation of a new nest.Communicated by R.F.A. Moritz     

大气质量综合评价的变权识别模型及其应用

根据属性识别理论 ,建立大气质量综合评价的变权识别模型 ,利用污染贡献率确定权重系数。与其它评价模型相比 ,变权识别模型还具有排序功能 ,实例分析表明该模型是有效的     

基于模糊识别的建筑物火灾危险性评价方法

笔者以传统的经典统计和模糊统计为基础 ,依据建筑物火灾危险性的影响因素 ,应用模糊识别理论及系统安全方法 ,建立了建筑物火灾危险性的评价指标体系 ;并应用集值统计方法对各项指标权重进行了处理。该方法改变了过去统计给出一个固定值的做法 ,而给出一个区间值 ,解决了对专家给出的指标“大约是多少”这一概念的定量化。为了验证了评价模型的准确性 ,将该理论应用到某购物商场火灾危险性评价中 ,取得了满意效果 ,为建筑物防火设计以及安全管理提供了可行的依据。     

An absence of aggression between non-nestmates in the bull ant <Emphasis Type="Italic">Myrmecia nigriceps</Emphasis>

The ability of social insects to discriminate against non-nestmates is vital for maintaining colony integrity, and in most social insect species, individuals act aggressively towards non-nestmates that intrude into their nest. Our experimental field data revealed that intra-colony aggression in the primitive bulldog ant Myrmecia nigriceps is negligible; our series of bioassays revealed no significant difference in the occurrence of aggression in trials involving workers from the same, a close (less than 300 m) or a far (more than 1.5 km) nest. Further, non-nestmate intruders were able to enter the nest in 60% of our trials; a similar level was observed in trials involving nestmates. These results suggest that workers of M. nigriceps are either unable to recognize alien conspecifics or that the costs of ignoring workers from foreign colonies are sufficiently low to favor low levels of inter-colony aggression in this species.     

宋代地震灾害与政府应对

地震灾害是给人类社会造成极大破坏的自然灾害之一。根据《宋史》等书记载,对宋代320年间的地震灾害进行初步的统计和分析,以认识两宋地震灾害的基本状况。地震发生后,宋朝政府积极展开救灾与论政,以帮助灾区度过困难并总结治国方略得失,以增强政府抵御灾害的能力。     

考虑颜色特征最优组合的CART决策树火灾图像识别方法*

针对火灾图像识别过程中颜色特征数量多、特征间相关性复杂、难以在多维特征融合过程中有效融合图像颜色特征等问题,提出1种考虑颜色特征最优组合的CART决策树火灾图像识别方法。首先,在Lab、RGB、HSV 3种色彩模式下基于图像颜色特征提取火灾图像特征序列;其次,分别在3种色彩模式下基于精细决策树与特征随机排列组合方法提取颜色特征中最优组合特征;最后,将提取的火灾图像最优组合特征序列作为CART决策树输入进行模型训练,并通过测试样本以及其他机器学习方法进行模型泛化能力的分析。研究结果表明:本文方法寻找出识别火灾图像的最优颜色特征组合为“Kb1+Var1+Kg+Kb2+Var2+Kh+Ks+Kv”;CART决策树方法对于火灾图像识别的测试准确度可达84.5%,其分类效果明显优于其他决策树类与集成树类方法;9折为最佳交叉验证折数,其测试准确度可达86.47%,与5折交叉验证相比明显提升14.77%。研究结果可为火灾图像识别提供方法基础。     

When to be neighbourly: differential agonistic responses in the lizard Platysaurus broadleyi

Differential treatment of neighbours and strangers (the dear enemy phenomenon) can reduce the costly effects of territory defence. Individual recognition, and by extension the dear enemy phenomenon, was examined in the cordylid lizard Platysaurus broadleyi. I had no knowledge of familiarity between individuals and therefore classed intruders as neighbours or non-neighbours and tested for differences in agonistic response consistent with the dear enemy phenomenon. In the dear enemy phenomenon, levels of aggression are inversely related to degree of familiarity such that residents are more tolerant of immediate neighbours than distant territory holders. A manipulative field experiment in conjunction with field observations of known territory holders revealed that resident males allowed neighbours to approach more closely than non-neighbours before challenging them, residents were more aggressive towards non-neighbours than neighbours, contests between neighbours were significantly longer than between neighbours and non-neighbours and contests between residents and non-neighbours were likely to result in a win for the resident, while neighbours frequently drew contests. These results suggest a level of recognition consistent with the dear enemy phenomenon. I also manipulated front leg colour to test the hypothesis that it alone could serve as a cue for individual recognition. I found no support for this hypothesis and suggest that multiple cues operate in individual recognition. Received: 4 March 1999 / Received in revised form: 11 April 1999 / Accepted: 19 April 1999     

Why are larvae of the social parasite wasp <Emphasis Type="Italic">Polistes sulcifer</Emphasis> not removed from the host nest?

A challenge for parasites is how to evade the sophisticated detection and rejection abilities of potential hosts. Many studies have shown how insect social parasites overcome host recognition systems and successfully enter host colonies. However, once a social parasite has successfully usurped an alien nest, its brood still face the challenge of avoiding host recognition. How immature stages of parasites fool the hosts has been little studied in social insects, though this has been deeply investigated in birds. We look at how larvae of the paper wasp obligate social parasite Polistes sulcifer fool their hosts. We focus on cuticular hydrocarbons (CHCs), which are keys for adult recognition, and use behavioral recognition assays. Parasite larvae might camouflage themselves either by underproducing CHCs (odorless hypothesis) or by acquiring a chemical profile that matches that of their hosts. GC/MS analyses show that parasite larvae do not have lower levels of CHCs and that their CHCs profile is similar to the host larval profile but shows a reduced colony specificity. Behavioral tests show that the hosts discriminate against alien conspecific larvae from different colonies but are more tolerant towards parasite larvae. Our results demonstrate that parasite larvae have evolved a host larval profile, which overcomes the host colony recognition system probably because of the lower proportion of branched compounds compared to host larvae. In some ways, this is a similar hypothesis to the odorless hypothesis, but it assumes that the parasite larvae are covered by a chemical blend that is not meaningful to the host.