Ecology. Weather ruins winter vacations

There has been increasing concern over the decline in many migratory bird species. As Saether discusses in his Perspective, evidence is accumulating (Sillett et al.) that climate change resulting from the El Ni?o Southern Oscillation affects both the survival rate of adult birds at tropical wintering sites and their reproductive rate at summer breeding grounds in the Northern Hemisphere.     

Parental care and clutch sizes in North and South American birds

The evolutionary causes of small clutch sizes in tropical and Southern Hemisphere regions are poorly understood. Alexander Skutch proposed 50 years ago that higher nest predation in the south constrains the rate at which parent birds can deliver food to young and thereby constrains clutch size by limiting the number of young that parents can feed. This hypothesis for explaining differences in clutch size and parental behaviors between latitudes has remained untested. Here, a detailed study of bird species in Arizona and Argentina shows that Skutch's hypothesis explains clutch size variation within North and South America. However, neither Skutch's hypothesis nor two major alternatives explain differences between latitudes.     

Brood parasitic cowbird nestlings use host young to procure resources

Young brood parasites that tolerate the company of host offspring challenge the existing evolutionary view of family life. In theory, all parasitic nestlings should be ruthlessly self-interested and should kill host offspring soon after hatching. Yet many species allow host young to live, even though they are rivals for host resources. Here we show that the tolerance of host nestlings by the parasitic brown-headed cowbird Molothrus ater is adaptive. Host young procure the cowbird a higher provisioning rate, so it grows more rapidly. The cowbird's unexpected altruism toward host offspring simply promotes its selfish interests in exploiting host parents.     

Constraints in the evolution of sex ratio adjustment

When the relative fitness of male and female offspring varies with environmental conditions, evolutionary theory predicts that parents should adjust the sex of their offspring accordingly. Qualitative and even quantitative support for this prediction is striking in some taxa but much less convincing in others. Explaining such variation across taxa in the fit of sex ratio theory remains a major challenge. We use meta-analysis to test the role of two constraints in the evolution of sex ratios. Based on analysis of sex ratio skews in birds and wasps, we show that (i) mechanisms of sex determination do not necessarily constrain the evolution of sex ratio adjustment, and (ii) parental ability to predict their offsprings' environment influences the evolution of sex ratio patterns across taxa. More generally, our results show that multiple constraints may determine the precision of adaptation.     

Reduced egg investment can conceal helper effects in cooperatively breeding birds

Cooperative breeding systems are characterized by nonbreeding helpers that assist breeders in offspring care. However, the benefits to offspring of being fed by parents and helpers in cooperatively breeding birds can be difficult to detect. We offer experimental evidence that helper effects can be obscured by an undocumented maternal tactic. In superb fairy-wrens (Malurus cyaneus), mothers breeding in the presence of helpers lay smaller eggs of lower nutritional content that produce lighter chicks, as compared with those laying eggs in the absence of helpers. Helpers compensate fully for such reductions in investment and allow mothers to benefit through increased survival to the next breeding season. We suggest that failure to consider maternal egg-investment strategies can lead to underestimation of the force of selection acting on helping in avian cooperative breeders.     

Parent-offspring coadaptation and the dual genetic control of maternal care

In many animal species, the amount of care provided by parents is determined through a complex interaction of offspring signals and responses by parents to those signals. As predicted by honest signaling theory, we show that in the burrower bug, Sehirus cinctus, maternal provisioning responds to experimental manipulations of offspring condition. Despite this predicted environmental influence, we find evidence from two cross-foster experiments that variation in maternal care also stems from two distinct genetic sources: variation among offspring in their ability to elicit care and variation among parents in their response to offspring signals. Furthermore, as predicted by maternal-offspring coadaptation theory, offspring signaling is negatively genetically correlated with maternal provisioning.     

不同抗病性小麦及后代光能转化特性研究

以亲本抗病与不抗病以及他们的分离后代的抗白粉病和感白粉病植株为材料,对其光合转化特性进行了比较研究。结果表明,无论是亲本还是后代,抗病植株旗叶的光合性能高于感病植株旗叶,其中光合速率(Pn),气孔导度(GS)的差异达到了极显著性差异水平(P<0.01),其余的差异不显著(P>0.05),同时发现感病植株旗叶的蒸腾速率(Evap)比抗病性植株的高;从亲本和分离后代水平来看,亲本感病材料(SY95-71)与抗病材料(7034)的光合速率(Pn),气孔导度(GS)等要低于分离后代,并且都达到了极显著性差异(P<0.01);而荧光参数则高于后代,但是统计分析表明差异不显著(P>0.05)。     

Genetic effects of captive breeding cause a rapid, cumulative fitness decline in the wild

Captive breeding is used to supplement populations of many species that are declining in the wild. The suitability of and long-term species survival from such programs remain largely untested, however. We measured lifetime reproductive success of the first two generations of steelhead trout that were reared in captivity and bred in the wild after they were released. By reconstructing a three-generation pedigree with microsatellite markers, we show that genetic effects of domestication reduce subsequent reproductive capabilities by approximately 40% per captive-reared generation when fish are moved to natural environments. These results suggest that even a few generations of domestication may have negative effects on natural reproduction in the wild and that the repeated use of captive-reared parents to supplement wild populations should be carefully reconsidered.     

Temperature and sperm incorporation in polyploid salamanders

Although most animals reproduce sexually, a number of all-female groups exist. Triploid hybrid salamanders appear to maintain themselves by using a male's sperm to activate their eggs, after which the sperm nucleus is eliminated (gynogenesis). The incidence of sperm nuclear incorporation in eggs of these salamanders depends on temperature. Triploid offspring derived gynogenetically are more frequent at lower temperature, whereas tetraploid offspring derived sexually are far more frequent at higher temperatures. Temperature-dependent variability in sperm nuclear incorporation helps explain the variability in reproductive modes reported for hybrid salamanders.     

杂交与亲本沙棘光合生理特性与产果量的差异性研究

以中国沙棘亚种丰宁雄(父本)与蒙古沙棘亚种乌兰沙林(母本),以及二者的杂交子代优选雌株为研究对象,比较了杂交子代沙棘与其亲本之间光合生理指标和产果量的差异.结果表明,亲本与杂交子代沙棘的净光合速率(Pn)、蒸腾速率(E)、气孔导度(GS)的日变化曲线均为单峰曲线,但峰值出现的时间不同;杂交子代沙棘的净光合速率、蒸腾速率和气孔导度均显著高于亲本,但是杂交子代的水分利用效率不及双亲,抗旱能力较差;而子代沙棘植株的果产量明显高于母本.因此,从抗旱能力方面评价,现有杂交子代还不是最佳的改良品种,尚需进一步选优和更新.     

野生稻渗入基因系对稻白叶枯病的抗性评价

用我国 7个白叶枯病致病型代表菌系对国际水稻研究所育成的 4种野生稻抗源供体的 65个渗入基因系进行了成株期抗性评价 .结果发现 :3种野生稻抗源供体的渗入基因系的抗性都明显高于其轮回亲本 ;3个渗入基因系 ( IR70 133- 12 1- 6- 6、IR70 133- 12 1- 9- 11、IR70 133- 12 1- 13- 1)对这 7个致病型菌系都表现高抗 .对其农艺性状的研究表明 ,这 3个渗入基因系的综合农艺性状良好 ,可作为今后水稻抗病育种的重要抗源亲本     

Evolution and development of sex differences in cooperative behavior in meerkats

In cooperatively breeding birds, where helpers of both sexes assist with the provisioning and upbringing of offspring who are not their own, males tend to contribute more than females to rearing young. This sex difference has been attributed to paternity uncertainty, but could also occur because males contribute more where they are likely to remain and breed in their group of origin. In contrast to most birds, female meerkats (Suricata suricatta) are more likely to breed in their natal group than males. We show that female meerkat helpers contribute more to rearing young than males and that female helpers feed female pups more frequently than males. Our results suggest that sex differences in cooperative behavior are generated by sex differences in philopatry and occur because females derive greater direct benefits than males from raising recruits to their natal group. These findings support the view that direct, mutualistic benefits are important in the evolution of specialized cooperative behavior.     

杂种小麦籽粒蛋白质含量和面团流变特性在F_1和F_2世代中的表现

选用 6个 T型不育系及其相应的保持系与 5个恢复系配制了 30个 T质杂种和 30个相应的 A质杂种、选用 4个 K型不育系及其保持系与 2个 K型恢复系配制了 8个 K质杂种和 8个相应的 A质杂种、选用 6个普通品种配制了 5个化杀组合 ,以研究杂种小麦籽粒的蛋白质含量和面团流变特性在 F1和 F2 中的表现。结果表明 :1胞质杂种 F1和 F2 籽粒蛋白含量均呈近正态分布 ;78%的组合 F1籽粒以超高亲为主 ,12 %的组合表现倾高亲 ;F2 籽粒以超高亲和偏高亲为主 ,约有 2 5%的组合表现近中亲。普通品种间的化杀杂种 F1籽粒以偏高亲和超高亲为主 ,F2 籽粒以近中亲和偏高亲为主。 2 T质杂种和相应 A质杂种的蛋白含量在 F1代差异不显著 ,但在 F2 代 T型胞质可显著提高籽粒蛋白含量 ;K型胞质可显著提高杂种籽粒 F1和 F2 的蛋白质含量。 3T型胞质可提高杂种小麦的面团流变特性 ;K型胞质使面团流变特性变劣。普通品种间的化杀杂种 F1和 F2 的面团流变特性都介于双亲之间 ,某些组合如早优 50 4×核生 2号组合的 F2 杂种表现倾高亲早优 50 4。     

Performance of Three Adelphocoris spp.（Hemiptera： Miridae） on Flowering and Non-flowering Cotton and Alfalfa

The genus Adelphocoris（Hemiptera： Miridae） is a group of key insect pests in cotton fields in China that includes three dominant species： A. suturalis（Jakovlev）, A. lineolatus（Goeze） and A. fasciaticollis（Reuter）. Previous field surveys have found that adults of these Adelphocoris species usually move onto specific host plants when the plants enter the flowering stage. To determine the potential trade-offs for this host-plant preference behavior, the performance of these three Adelphocoris spp. on flowering and non-flowering cotton and alfalfa were compared in the laboratory. The results showed that Adelphocoris spp. had significantly higher nymphal developmental and survival rates, along with increased adult longevity and fecundity on flowering cotton and alfalfa than on non-flowering plants of either species. In addition, compared with cotton plants, alfalfa generally promoted better performance of these three Adelphocoris species, especially for A. lineolatus. Simple correlation analysis indicated that female adult longevity was positively correlated to male adult longevity and female fecundity, and female fecundity was positively correlated to nymphal development and survival rates. This study demonstrated a positive correlation between adult preference and offspring/adult performance for all three Adelphocoris species, with no evidence of any trade-offs for this preference for flowering host plants. These findings support the hypothesis that hemimetabolous insects such as mirid bugs have positive adult preference-adult/nymphal performance relationships, which is likely due to the similar feeding habits and nutritional requirements of adults and nymphs.     

Toxicity of Neonicotinoid Pesticide Imidacloprid and Impediment of Ecosystem Services

In agro-ecosystems, pollinators perform a variety of ecological services. The ecological role of pollinators and their ecosystem services are critical to the health of many ecosystems. Pollination by birds and bees are recognized as an important ecosystem function maintaining the dynamics of agro-ecosystems. As agriculture covers a significant portion of the globe, it necessitates the evaluation of their ecosystem services. There are overwhelming evidence that pollinators are experiencing tremendous population decline. Global agricultural encroachment, agriculture intensification, changes in cropped pasture, urban development and extensive use of pesticides are the major threats to farmland birds. Despite ecological importance and global awareness, farmland birds and bees are often considered as species of low conservation value. The worldwide use of neonicotinoid insecticides has raised concern over the decline of pollinators in the farmlands globally. Neonicotinoids are neurotoxins, applied to variety of agricultural crops to control sucking and biting pests and are readily incorporated into plant cells, inclusive of pollen and nectar. Among neonicotinoids, imidacloprid is found to have startling effects, disrupting several ecosystem services, inhibiting pollination and threatening global food security. The study focuses on imidacloprid and its wider risk to the environment with effects on non-target pollinators especially birds and bees. Some of the effects on bees include disrupting social behavior, foraging and altered navigation and in birds reduced reproduction and offspring immunity. Though the scientific community is intently examining the potential effects of imidacloprid on pollinators, the research warrants further investigations with field-realistic concentrations and at relevant exposure levels. This would facilitate the functioning of pollinators and promote sustainable agriculture by reducing the impact of neonicotinoids. This review summarizes the potential lethal and sublethal effects of neonicotinoid pesticide imidacloprid on pollinators and other invertebrate groups and also helps us to better understand the extent of their toxicity.     

海南东寨港红树林湿地鸟类监测与研究

利用样线法年对海南东寨港红树林湿地的鸟类进行调查,并对鸟类的物种多样性和生境进行了分析。结果表明,东寨港红树林湿地共记录有鸟类11目26科65种,总数量为24531只,其中水鸟有41种,占调查总种数的63％。全年水鸟的种类和数量具有明显的季节性变化,均为越冬期较多,繁殖期较少。不同生境的鸟类群落组成及物种多样性在不同季节的差异性显著。     

Vesicular stomatitis virus (Indiana serotype): transovarial transmission by phlebotomine sandlies

Transovarial transmission of vesicular stomatitis virus (Indiana serotype) by experimentally infected Lutzomyia trapidoi and Lutzomyia ylephiletrix to their progeny was demonstrated. Virus was recovered from all developmental stages; mean virus titers from egg to first generation adult showed a four-log increase, indicating that virus multiplication occurred during development of the sandflies. Virus titers in first generation adult females were comparable to those found in their parents. These infected female sandflies transmitted vesicular stomatitus virus Indiana by bite to susceptible animals and transmitted the virus transovarially to their offspring (second generation). Results demonstrate a possible mechanism for transmission and maintenance of this virus in nature without a vertebrate (heat) host reservoir.     

RAPD分子标记技术在茶树亲子鉴定中的应用

为给茶树种质资源的鉴定、品种鉴定、亲子鉴定提供科学方法，通过对3个人工杂交组合的亲本及F1代进行RAPD分析。结果显示：双亲的RAPD谱带能在其F1代中表现出来，表现率分别为94.90%，97.92%,98.64%，说明3个杂交单株是其亲本的真正后代，这也表明RAPD技术在亲子鉴定中具有很强的适用性。同时从3个杂交组合的RAPD分析结果可以看出，双亲的RAPD谱带在F1代出现分离现象，这一结果表明茶树是一个杂合体。     

德宏水牛和摩拉水牛及杂交后代的遗传差异分析*

 为了解德宏水牛、摩拉水牛及二者杂交后代之间的遗传差异,本研究采用随机扩增多态性DNA标记技术,从70个随机引物中筛选出11个多态性丰富的引物对德宏水牛、摩拉水牛及二者杂交后代共80个个体进行了遗传变异检测,结果11条引物共产生89种扩增片段,多态片段73条,多态率82.02%。两亲本群体相对遗传距离为 0.220 3 ,杂交后代群体与德宏水牛、摩拉水牛群体的相对遗传距离分别为 0.101 7 和 0.135 3 ,表明杂交后代群体与两亲本群体间的遗传差异小于两亲本群体间的遗传差异,杂交后代群体与德宏水牛群体遗传关系更接近。     

两个意蜂品种及其杂交子代的形态特征和杂种优势分析

【目的】比较分析两个意蜂品种及其杂交子代间的形态特征差异和杂种优势情况,为进一步探究两个意蜂品系杂交子代的生产性能和杂种优势提供理论依据。【方法】采集意大利蜜蜂王浆高产蜂种、美意蜂种及其正交、反交子代4个类型共12群蜜蜂样本,每群测定分析15只,共测定40个形态指标,计算杂种优势率,同时进行相关的因素分析、区辨分析和聚类分析。【结果】在20个与意蜂体型大小相关的形态特征指标中,王浆高产蜂种有15个指标高于美意蜂种,反交子代中有17个指标高于正交子代;在8个与意蜂体色相关的形态特征指标中,王浆高产蜂种的色度平均值比美意蜂种的高,而反交子代的色度平均值比正交子代的低;在9个与生产力相关的形态特征指标方面,反交子代较正交子代更具杂种优势。4个类型意蜂品种的因素分析结果表明,3个主因素的总变异系数为53.291%,主要是与体型大小有关的特征指标;区辨分析结果表明,正交子代、反交子代与王浆高产蜂种基本聚在一起,美意蜂种则相对分开;聚类分析结果表明,反交子代与王浆高产蜂种、美意蜂种聚为一个分支,而正交子代单独为一个分支。【结论】蜜蜂亲本相同,但杂交组配方法不同,其后代的形态特征指标也存在明显差异。