Toxicity and attraction effects produced byMorinda citrifolia fruits on theDrosophila melanogaster complex of species

Summary The ripe fruit of the Indian mulberry,Morinda citrifolia, is the host plant forDrosophila sechellia but is highly toxic for three closely related species (D. melanogaster, D. simulans, D. mauritiana). A simple bioassay is described with which a clear dose response to the fruit was found for these species. Significant differences in reactivity to the ripe fruit were found among species. Tested strains ofD. simulans andD. mauritiana adults were more sensitive to the toxic properties of the fruit thanD. melanogaster. A marked intraspecific variability was shown inD. melanogaster. Reciprocal interspecific hybridizations betweenD. sechellia andD. mauritiana suggested an autosomal dominant control of resistance. MoreoverD. melanogaster intraspecific crossings suggested the influence of an additional X-linked factor. Responses of flies toMorinda fruit in different states were tested in a T olfactometer. The less resistant strains ofDrosophila generally showed less preference for the ripe fruit.     

Accounting for the Mesoscale Effects on the Air Pollution in Some Cases of Large Sulfur Pollution in Bulgaria or Northern Greece

The objective of the present work is to demonstrate the influence of the meso-scale dynamic phenomena on the larger scale air pollution characteristics. A limited set of episodes with very large sulphur pollution in Bulgaria or Northern Greece is chosen for the study. A 3D quasi-hydrostatic model of the meso-scale dynamics, based on the Businesque approximation (the formulation of Guthman) is used for the purpose. Some numerical experiments for the Balkan Peninsula are carried out under different background (synoptic) conditions. The simulated flow systems outline the main topography effects, typical for the region, such as slope winds, channelling of the air flows or blocking effects. Numerical simulations of the air pollution transport are also carried out, with and without accounting for the meso-scale deformations of the wind field. The comparison of the air pollution characteristics, obtained in both the cases demonstrates that the underlying surface heterogeneity in some of the synoptic situations may have influence not only on the detailed air pollution field in the region, but also on some larger scale pollution characteristics – the total pollution quantity in the air above the countries, the mean surface concentration, the pollution fluxes trough the country boundaries, dry and wet deposition.     

[CO2]和温度增加的相互作用对植物生长的影响

ＣＯ2 和温度是影响植物生长、发育和功能的两个关键因子 .在过去一个世纪中 ,[ＣＯ2 ]从 2 80 μｍｏｌ/ｍｏｌ增加到 36 0μｍｏｌ/ｍｏｌ且每年增长速率为 1～ 5 μｍｏｌ/ｍｏｌ,到 2 0世纪末达到更高的浓度[1] .最近的模型预测表明 ,到 2 10 0年 ,全球表面温度可能会增加 1～ 4 .5℃ [2 \〗.ＣＯ2 是光合作用的底物 ,而且还是初级代谢过程 (气孔反应和光合作用 )、光合同化物分配和生长的调节者 .温度几乎影响植物所有的生物学过程 .因此 ,在全球气候变化要素中 ,大气 [ＣＯ2 ]和温度升高对植物的生理过程和生物量及产量具有极为重要的…     

Environmental conditions influence egg color of reed warblers <Emphasis Type="Italic">Acrocephalus scirpaceus</Emphasis> and their parasite,the common cuckoo <Emphasis Type="Italic">Cuculus canorus</Emphasis>

The outer layer of the eggshell in birds is in many cases covered by pigments that are assumed to be genetically determined traits with a negligible environmental component. To test the hypothesis that spring environmental conditions (i.e., temperature and rainfall) may affect bird egg pigmentation, we measured by spectrophotometry and photography egg coloration and spottiness on reed warbler (Acrocephalus scirpaceus L.) clutches parasitized by the common cuckoo (Cuculus canorus L.) collected over a period of 24 years and preserved in the Zoological Museum, Copenhagen, Denmark. In addition, we investigated whether spring environmental conditions may influence the coevolutionary relationship between the cuckoo and its host via changes in cuckoo–host egg matching. Generalized mixed models revealed that reed warbler eggs were more brilliant in those springs with a higher rainfall and tended to be bluer and greener in springs with a lower relative temperature. On the other hand, cuckoo eggs were bluer and greener in springs with a higher rainfall. Cuckoo–host egg matching in blue-greenness and spottiness was better in springs with a higher rainfall. These results provide support for the existence of an environmental component on bird egg coloration and suggest that environmental factors may potentially affect the outcome of important features of the arms race between cuckoos and reed warblers.     

Environmental and genetic influences on mating strategies along a replicated food availability gradient in guppies (Poecilia reticulata)

Food availability is expected to influence the relative cost of different mating tactics, but little attention has been paid to this potential source of adaptive geographic variation in behavior. Associations between the frequency of different mating tactics and resource availability could arise because tactic use responds directly to food intake (phenotypic plasticity), because populations exposed to different average levels of food availability have diverged genetically in tactic use, or both. Different populations of guppies (Poecilia reticulata) in Trinidad experience different average levels of food availability. We combined field observations with laboratory “common garden” and diet experiments to examine how this environmental gradient has influenced the evolution of male mating tactics. Three independent components of variation in male behavior were found in the field: courtship versus foraging, dominance interactions, and interference competition versus searching for mates. Compared with low-food-availability sites, males at high-food-availability sites devoted more effort to interference competition. This difference disappeared in the common garden experiment, which suggests that it was caused by phenotypic plasticity and not genetic divergence. In the diet experiment, interference competition was more frequent and intense among males raised on the greater of two food levels, but this was only true for fish descended from sites with low food availability. Thus, the association between interference competition and food availability in the field can be attributed to a genetically variable norm of reaction. Genetically variable norms of reaction with respect to food intake were found for the other two behavioral components as well and are discussed in relation to the patterns observed in the field. Our results indicate that food availability gradients are an important, albeit complex, source of geographic variation in male mating strategies.     

Reproductive Success of Captive-Bred Steelhead Trout in the Wild: Evaluation of Three Hatchery Programs in the Hood River

Abstract:  Population supplementation programs that release captive-bred offspring into the wild to boost the size of endangered populations are now in place for many species. The use of hatcheries for supplementing salmonid populations has become particularly popular. Nevertheless, whether such programs actually increase the size of wild populations remains unclear, and predictions that supplementation fish drag down the fitness of wild fish remain untested. To address these issues, we performed DNA-based parentage analyses on almost complete samples of anadromous steelhead ( Oncorhynchus mykiss ) in the Hood River in Oregon (U.S.A.). Steelhead from a supplementation hatchery (reared in a supplementation hatchery and then allowed to spawn naturally in the wild) had reproductive success indistinguishable from that of wild fish. In contrast, fish from a traditional hatchery (nonlocal origin, multiple generations in hatcheries) breeding in the same river showed significantly lower fitness than wild fish. In addition, crosses between wild fish and supplementation fish were as reproductively successful as those between wild parents. Thus, there was no sign that supplementation fish drag down the fitness of wild fish by breeding with them for a single generation. On the other hand, crosses between hatchery fish of either type (traditional or supplementation) were less fit than expected, suggesting a possible interaction effect. These are the first data to show that a supplementation program with native brood stock can provide a single-generation boost to the size of a natural steelhead population without obvious short-term fitness costs. The long-term effects of population supplementation remain untested.     

根系分泌物与根际微生物相互作用研究综述

对几种主要根系分泌物与根际微生物之间的相互作用关系和影响机理的研究进行了综述，同时提出了今后在根系分泌物及根际微生态方面需要深入研究的几个问题。     

土壤钙的生物有效性及与其它元素的相互作用

根据国内有关土壤钙素的研究文献、总结了土壤钙的生物有效性.土壤钙与其它元素的相互作用,以及钙在土壤中的固定、移动的研究进展,提出了钙肥的施用原则.其施用原则应该是平衡且适量。     

三水市农业生态系统经济能值投入产出分析

进行生态学与经济学系统分析方法的交叉探索,将能值这一全新的生态经济度量尺度引入经济学投入产出分析表,对广东省珠江三角洲三水市农业生态系统经济能值的直接消耗系统和完全消耗系统分析,弥补经济学分析中自然环境投入价值缺失的同时,为复合系统能值分析中各系统间互作分析的量化评价探索了新的途径。分析结果表明:三水市农业生态系统中种植业、渔业、畜牧业和林业之间存在经济能值的依存关系,有着直接的相互作用。种植业、渔业和畜牧业子系统间的经济能值交流网络较为发达。在种植业、渔业、畜牧业和林业中,渔业对种植业的完全消耗系数最大,达到3.461×10-2,畜牧业对种植业的完全消耗系数也最大,达到了8.423×10-2;种植业对渔业的完全消耗系数最大,达到了7.685×10-2。林业与种植业、渔业、畜牧业互相的完全消耗系数都比较小,林业和其它三个子系统的经济能值交流较弱。种植业子系统是整个三水市农业生态系统的基础,渔业和畜牧业在种植业的基础上发展,对物质和能量的再利用起了重要作用。林业子系统是三水市农业生态系统内部物质能量交流网络的薄弱环节。三水市农业生态系统的内部结构有待进一步调整,以加强各子系统间的互作,提高物质与能量的使用效率。     

煤烟型复合污染物相互作用与转移过程及其特点

粉尘,ＳＯ２,ＮＯｘ等的煤烟型复合污染是我国尤其是南方我的主要类型。本文根据实验观测,详细分析了主要污染物间的相互作用过程及其复污染物从产生,转移至植物界面的运动过程及其特点。