Kin-preferential cooperation,dominance-dependent reproductive skew,and competition for mates in communally nesting female house mice

Little is known about the behavioural mechanisms facilitating kin-preferential communal breeding in wild house mice (Mus domesticus). We evaluated the effect of kinship and male availability on aggression, social structure and reproductive skew in groups of female mice freely interacting and reproducing in semi-natural indoor enclosures. Triplets of either sisters or non-sisters were established in enclosures provided with either one or three littermate males, which were unrelated and unfamiliar to the females. Sisters were more spatially associated and less aggressive than non-sisters, leading to higher incidences of communal breeding and reproduction. This is in agreement with theoretical considerations on kin selection in house mice. Reproductive success was highly skewed in favour of dominant females due to subordinate infertility or complete loss of first litters, which might have been caused by dominant females. In spite of this, subordinates only rarely dispersed from the enclosures, suggesting that perceived dispersal risk generally outweighed relatively reduced reproductive potentials. Aggression levels among females were significantly higher when one male was available, compared to when three males were available. We suggest that this might result from higher female-female competition for mates, due to the risk of missing fertilisation when synchronously oestrous females encounter limited numbers of males in a deme. Our results indicate that, first, communal nursing in house mice might have evolved to make the best out of a bad job rather than to enhance offspring fitness; and, second, that female-female mate-competition might play an important role in shaping female social structure in this polygynous mammal.Electronic Supplementary Material Supplementary material is available in the online version of this article at Communicated by F. Trillmich     

Ontogenetic shifts in fusion–rejection thresholds in a colonial marine hydrozoan,<Emphasis Type="Italic"> Hydractinia symbiolongicarpus</Emphasis>

Like many modular organisms, genetically distinct colonies of the hydrozoan Hydractinia symbiolongicarpus naturally fuse to produce chimeras. One of the principal cooperative benefits of fusion arises from the increased size of the resulting chimeric individual, which may enhance survivorship. However, fusion also promotes conflict through competition between cell lineages for representation in reproductive tissues. Previous studies on H. symbiologicarpus show that, consistent with kin selection theory, a highly polymorphic self/non-self recognition system limits fusion to close kin. However, these recognition systems are intrinsically subject to error. Conspecific acceptance threshold theory predicts that as the costs and benefits of making recognition errors change, or the frequencies of encounters between acceptable and unacceptable kin vary, the recognition system should respond. Specifically, as the benefits of acceptance decline or the frequency of encounters with unacceptable individuals increases, the acceptance threshold should become more restrictive. We tested this hypothesis by monitoring changes in the expression of fusion/rejection behaviors of H. symbiolongicarpus during colony establishment, a period of high mortality when the size-dependent benefits of fusion may be changing most rapidly, and the frequency of encounters with close kin declines. Across seven full-sib families, fusion frequencies between pairs of sibling colonies declined from 73% for 3-day-old colonies to 58% by day 12. This decline is consistent with optimal acceptance threshold theory. However, the period of maximum decline also corresponds to an interval during which the recognition effector mechanism becomes fully functional, suggesting that the shift to a more restrictive conspecific acceptance threshold may reflect an intrinsic constraint on recognition system maturation.Communicated by T. Czeschlik     

Learning affects the preference for parasitized hosts of the facultative kleptoparasitoid <Emphasis Type="Italic">Eupelmus vuilleti</Emphasis>

For a facultative kleptoparasite, the decision to allocate time and energy to search for a prey or for a kleptoparasite opportunity could be influenced by its prior experience. In this study, we investigated the influence of experience on the proportion of the facultative kleptoparasitoid Eupelmus vuilleti females choosing an unparasitized host or a host parasitized by Dinarmus basalis. When exploiting hosts previously parasitized by D. basalis, a large proportion of E. vuilleti females reused the hole drilled by the D. basalis female, which led to a reduction in the time needed to reach the host. When submitted to successive choice tests between an unparasitized host and a host parasitized by D. basalis in a natural host-plant system, the proportion of E. vuilleti females which choose the parasitized host increased with the female experience. The same experiment carried out with an artificial host-plant system allowing an easy access to the host did not show a variation of the females’ choice with experience. A reward—here a faster access to the host through the hole drilled by the D. basalis female—seems necessary to mediate the associative learning expressed by the preferential choice of the parasitized host.     

Family insurance: kin selection and cooperative breeding in a solitary primate (Microcebus murinus)

Lactation imposes substantial physiological costs on mothers and should therefore not be directed towards foreign offspring. Such allonursing, however, is common in mammal species that share roosts. Hypotheses to explain allonursing among such plural breeders include misdirected parental care, milk evacuation, brood parasitism, reciprocity, and kin selection. The necessary behavioral data, in combination with data on kinship and kin recognition, have rarely been available to distinguish among these explanations, however. In this study, we provide evidence for cooperative nursing and adoption by plural-breeding females in a nocturnal primate, the gray mouse lemur (Microcebus murinus), in which females forage solitarily during the night, but form day-time sleeping groups with one to two other females. We observed 34 resident females in an 8 ha study area in Kirindy Forest, Madagascar, over three consecutive annual breeding seasons and determined genetic relationships among all members of this population. Five sleeping groups of adult females were filmed inside their roosts during one breeding season after females gave birth. The composition of groups changed substantially across years, but they always consisted of close maternal relatives. All females within a group gave birth to one to three infants. They regularly transferred only their own offspring among roosting sites, demonstrating an ability to discriminate between their own and other’s offspring, but they regularly groomed and nursed related offspring other than their own and adopted related dependent young after their mother’s death. Kin selection may therefore be the main selective force behind cooperative breeding among these closely related females with a high mortality risk, providing each of them with family insurance.     

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.     

Interspecific utilisation of wax in comb building by honeybees

Beeswaxes of honeybee species share some homologous neutral lipids; but species-specific differences remain. We analysed behavioural variation for wax choice in honeybees, calculated the Euclidean distances for different beeswaxes and assessed the relationship of Euclidean distances to wax choice. We tested the beeswaxes of Apis mellifera capensis, Apis florea, Apis cerana and Apis dorsata and the plant and mineral waxes Japan, candelilla, bayberry and ozokerite as sheets placed in colonies of A. m. capensis, A. florea and A. cerana. A. m. capensis accepted the four beeswaxes but removed Japan and bayberry wax and ignored candelilla and ozokerite. A. cerana colonies accepted the wax of A. cerana, A. florea and A. dorsata but rejected or ignored that of A. m. capensis, the plant and mineral waxes. A. florea colonies accepted A. cerana, A. dorsata and A. florea wax but rejected that of A. m. capensis. The Euclidean distances for the beeswaxes are consistent with currently prevailing phylogenies for Apis. Despite post-speciation chemical differences in the beeswaxes, they remain largely acceptable interspecifically while the plant and mineral waxes are not chemically close enough to beeswax for their acceptance.     

Differential aggressiveness between fire salamander (<Emphasis Type="Italic">Salamandra infraimmaculata</Emphasis>) larvae covaries with their genetic similarity

Responding differentially to kin and non-kin is known to be adaptive in many species. One example is the inclusive fitness benefits of reducing aggression toward closer relatives. Little is known, however, about the ability of animals to assess differential degrees of genetic relatedness and to respond accordingly with differential levels of aggression. In the present study, we tested whether aggressiveness between body mass-matched pairs of fire salamander (Salamandra infraimmaculata) larvae covaried with the genetic similarity between them. We quantified aggressiveness at three levels of genetic similarity by selecting pairs within and across pools from recently genotyped populations. We also assessed aggression between pairs of siblings. Aggression and associated injuries decreased as genetic similarity increased across the groups. These findings suggest that cannibalistic salamanders can assess their degree of genetic relatedness to conspecifics and vary their behavioral responses depending on the degree of similarity between them along a genetic relatedness continuum.     

荧光光谱结合主成分分析对赤潮藻的识别测定

利用主成分分析和非负最小二乘法,建立了我国近海常见的11种赤潮藻在属水平上的活体荧光识别测定技术.利用Delaunay三维插值法,消除浮游藻三维荧光光谱的瑞利散射和拉曼散射峰, 根据Fisher判别分析方法对各主成分及其组合的分辨能力的判别结果,确定赤潮藻三维荧光光谱的第一主成分得分谱和第二主成分得分谱作为赤潮藻识别特征谱,建立赤潮藻荧光特征谱库,在此基础上,利用非负最小二乘法对11种赤潮藻在属水平上进行识别测定,赤潮藻的识别正确率≥85%,其中9种赤潮藻的识别正确率≥90%,特别是对于近几年东海发生赤潮频率极高的东海原甲藻（Prorocentrum donghaiense）、中肋骨条藻（Skeletonema costatum）和裸甲藻（Gymnodinium sp.）,识别正确率≥95%.本研究表明,利用主成分分析提取赤潮藻三维荧光光谱特征以实现赤潮藻在属水平上的识别测定是可行的.     

油品储罐区风险评价技术研究

本文通过分析影响储罐安全的五大因素18项指标,系统建立了单个油品储罐的安全评价指标体系,采用层次分析-模糊综合评价方法,实现单个油品储罐的安全状况分级。并结合区域定量风险评价方法,实现对油品储罐区的整体风险评价。以某油品储罐区为例,利用建立的指标体系与区域风险评价方法,给出了单个储罐安全等级以及储罐区个人风险等值线分布图和社会风险曲线。更全面的给出了储罐区单个储罐与罐区整体不同层次的风险状况,为油品储罐区规划,管理及事故预防和应急救援提供依据。     

宜宾-重庆段川江高阶地物质来源的定量分析--判别分析在重矿物分析中的应用

川江倒流的问题可以利用川江高阶地的物质来源进行佐证,如果川江上段高阶地的物质来源于东部而不是西部,则川江就有倒流的可能性。重矿物组合可以部分地表征物质来源。对宜宾－重庆段川江高阶地的重矿物种类及其含量做了判别分析,得到了比较理想的结果。将金沙江和重庆以下的重矿物组合特征作为已知的两个分类,判别重庆以上（包括宜宾和重庆的样品）的高阶地重矿物组合特征究竟应该属于哪种类型。以重矿物种类和含量为变量进行分析的回代结果正确率分别为93.1%和96.6%。川江高阶地重矿物组合与金沙江差异较大,估计当时该阶地物质来源与金沙江关系不大。