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The Science of Nature - 相似文献
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The sperm of the brown shrimp Penaeus aztecus are nonflagellated and non-motile. In vitro fertilization can be obtained when mature eggs removed from female shrimp are added to dense sperm suspensions in seawater and agitated in a manner simulating natural spawning. 相似文献
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Ashley?J.?W.?WardEmail author Philip?Thomas Paul?J.?B.?Hart Jens?Krause 《Behavioral ecology and sociobiology》2004,55(6):561-568
Behavioural variation is known to occur between individuals of the same population competing for resources. Individuals also vary with respect to their boldness or shyness. An individuals position along the shy-bold axis may be defined as the extent to which it is willing to trade off potentially increased predation risks for possible gains in resources. Similarly, group living may be interpreted as a trade-off between anti-predatory tactics and foraging efficiency. The responses of three-spined sticklebacks (Gasterosteus aculeatus) were tested across four social contexts to assess relative boldness or shyness and to further examine whether their behaviour would be consistent within and between contexts. Individuals displayed consistent responses within and between the first two contexts: those individuals which resumed foraging rapidly after a simulated aerial predator attack also displayed low shoaling tendencies. Such fish were deemed to be bold, whilst those which displayed the converse behaviour, slow resumption of foraging and a high shoaling tendency, were deemed to be shy. In a third context, bold individuals out-competed shy conspecifics for food. Boldness was also positively correlated with growth over a 6-week period. The position adopted by an individual within a group is usually interpreted as a trade-off between predation risk and foraging efficiency—both are greater at the front of a mobile group. Bold individuals showed significantly stronger tendencies towards front positions than shy conspecifics. The results suggest that, contrary to some previous studies on other animals, bold or shy behaviour in sticklebacks is consistent between contexts.Communicated by T. Czeschlik 相似文献
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Monofunctionalized cyclodextrin polymers for the removal of organic pollutants from water 总被引:1,自引:0,他引:1
B. B. Mamba R. W. Krause T. J. Malefetse E. N. Nxumalo 《Environmental Chemistry Letters》2007,5(2):79-84
Water is an important resource for domestic, industrial, agricultural and recreational purposes. The quality of water is however
significantly deteriorating due to the accumulation of organic pollutants in aqueous systems. Conventional water treatment
technologies fail to remove these contaminants to desirable levels. Recent studies have revealed that cyclodextrin nanoporous
polymers are capable of absorbing pollutants from water to parts per billion levels. We have demonstrated that functionalised
cyclodextrin polymers have enhanced absorption capacities for some organic pollutants. Here we report the synthesis of several
insoluble monosubstituted cyclodextrin polymers or “nanosponges”. We show that these polymers have improved abilities in the
absorption of p-nitrophenol and pentachlorophenol from aqueous solutions. 相似文献
90.
Social structure and co-operative interactions in a wild population of guppies (Poecilia reticulata)
D. P. Croft R. James P. O. R. Thomas C. Hathaway D. Mawdsley K. N. Laland J. Krause 《Behavioral ecology and sociobiology》2006,59(5):644-650
In contrast to the substantial number of theoretical papers that have examined the mechanisms by which cooperation may evolve,
very few studies have investigated patterns of co-operation in natural animal populations. In the current study, we use a
novel approach, social network analysis, to investigate the structure of co-operative interactions in the context of predator
inspection in a wild population of guppies (Poecilia reticulata). Female guppies showed social preferences for stable partners, fulfilling a key assumption made by models of reciprocity.
In the laboratory, wild female guppies disproportionately engaged in predator inspection with others with whom they had strong
social associations. Furthermore, pairs of fish that frequently engaged in predator inspection did so in a particularly co-operative
way, potentially reducing costs associated with predator inspection. Taken together, these results provide evidence for assortative
interactions forming the basis of co-operation during predator inspection in a natural fish population. The occurrence of
highly interconnected social networks between stable partners suggests the existence of co-operation networks in free-ranging
populations of the guppy. 相似文献