不同来源和粒径的胶体对光合细菌生长的效应

天然胶体是近岸海域细菌和浮游植物可利用氮的一个重要来源 ,其含量的增加可促进藻类的繁殖和生长 ,有时甚至引发赤潮。研究显示 ,细菌在高分子量胶体存在下的生长和代谢速率比在低分子量中的提高 3～ 6倍 ,暴露在阳光下的胶体有机物可释放生物可利用的富氮组分 ,进而提高细菌对胶体的分解。利用错流超滤技术从河流、河口、海洋水体和微藻培养液中提取胶体 ,研究了胶体来源和粒径对光合细菌 (PSB,沼泽红假单胞菌 Rhodopseudomonaspalustris)生长的影响。结果表明 ,在一定的胶体有机碳浓度范围 ,河流胶体 (0～ 2 81.0μmol/ L )、河口胶体 (0～ 12 1.2μmol/ L )、海洋胶体 (0～ 88.8μmol/ L )和生源胶体 (7.7～5 4 8.6μmol/ L )都能促进 PSB的生长 ,分别使其相对增长率平均提高了 4 7.3%～ 196 .2 % ,3.6 %～ 9.3% ,8.1%～ 10 .4 %和2 .4 %～ 6 .9%。其中 ,PSB在河流胶体中的相对增长率的平均值 (Y)与有机碳浓度 (CDOC)呈对数相关 (Y (% ) =- 193.7 70 .7ln CDOC) ,表明高浓度的河流胶体 ,对 PSB生长的促进效果更显著。两种生源胶体中 ,海水小球藻胶体 (0～ 5 4 8.6μmol/ L )对PSB生长的促进作用大于球等鞭金藻胶体 (7.7～ 384 .4 μmol/ L) ;PSB在粒径为 10 k D～ 0 .2 2 μm的海洋胶体中的生长大于     

Effect of selection intensity and population size on percent oil in maize,Zea mays L

Summary The effect of selection intensity and population size on the response to selection for percent oil in the grain of maize (Zea mays L.) was evaluated in a replicated experiment over ten cycles of selection. An open-pollinated variety, Armel's Reid Yellow Dent, was divided into subpopulations of 6,10 and 50 plants. Selection proportions of 17% and 5% were imposed upon each subpopulation. Selection was based on the percentage of oil in individual kernels as determined by wide-line nuclear magnetic resonance spectroscopy. As expected, total response to selection increased with larger population sizes and selection intensities. The concave shape of the response curves suggested that an appreciable part of the genetic variance can be attributed to additive genes at high initial frequencies, dominance genes at low initial frequencies, or to the generation of negative linkage disequilibrium due to selection. The consistently greater loss of vigor experienced by the more intensely selected populations reflects the enhancement of inbreeding due to artificial selection, an effect that increases with the intensity of selection. The results indicate that combined selection, based on kernels and using within- and amongfamily information, will be more efficient than other conventional selection procedures, including the normal combined scheme where selection is based on plants.Deceased     

Effects of crayfish size,orientation, and movement on the reactive distance of largemouth bass foraging in clear and turbid water

Laboratory experiments were performed in clear and turbid water to determine the effects of prey size, orientation, and movement on the reactive distance of largemouth bass (Micropterus salmoides) when feeding on crayfish (Procambarus acutus). In clear water, the reactive distance increased linearly with an increase in prey size, and prey movement resulted in a significant increase in the reactive distance. Prey orientation (head-on versus perpendicular) did not change the reactive distances. In moderately turbid water, the reactive distance did not increase with increased prey size, and prey movement did not result in any changes in the reactive distance. The absence of any effects of prey orientation in clear water or prey movement in turbid water is inconsistent with results from studies using different species (primarily planktivorous fish). I propose that largemouth bass change their foraging tactics as prey visibility changes. When prey are highly visible (low turbidity), predators attack (react) only after prey recognition, which is based on multiple cues such as prey size (length, width) and movement. When prey are less visible (high turbidity), predators attack immediately upon initial prey sighting, which does not depend on prey size or movement.     

Female‐biased migration of stream‐dwelling Dolly Varden in the Shiisorapuchi River, Hokkaido, Japan

The first evidence for female‐biased migration in a partially migratory stream‐dwelling salmonid the Dolly Varden Salvelinus malma , a phenomenon well known in sea‐run and lake‐run populations, is presented. Dolly Varden in the Shiisorapuchi River in central Hokkaido, Japan, used both tributaries, of which there are many, and the main stem, but spawned only in tributaries. The size structures of Dolly Varden (≥age 1 + years) in tributaries were unimodal (<100 mm fork length, L _F) during non‐spawning seasons but changed to bimodal during spawning seasons (lower mode <110 mm, upper mode >120 mm L _F). Mature individuals were observed in both modal groups. From the trapping and census data, the small group appeared to be tributary resident and the large group main stem migrant. Males were common in both resident and migrant components. Most females, however, migrated to the main stem to mature, indicating female‐biased migration.     

水生细菌生物量的估算方法*

细菌的生物量是海洋微生物研究的关键参数之一。目前,细菌生物量估算方法主要根据其体积的大小进行换算,但换算的方式也不尽一致。对细菌体积和细菌碳含量主要的测定方法、体积与生物量之间换算系数、换算模式进行介绍,评述。认为流式细胞术是测定细菌体积较为合适的方法,X-射线微量分析法是测定单个细菌生物量(碳含量)最合适的方法,异速生长模式是目前生物量换算过程较为常用的模式。     

暂时与群体分离的个体藏马鸡的反捕食警戒

通过与同伴分担捕食风险 ,生活在稳定群体中的个体动物可以获得长期的适合度利益 ,但同时它们不得不承担食物竞争所带来的潜在代价。这种代价常常取决于食物资源的类型。当好的食物资源出现时 ,一些个体可以离开群体而独享这种资源。了解这些临时游离者如何组织其反捕食行为 ,在进化生态学上是有意义的。藏马鸡 (Crossoptilonharmani)是西藏雅鲁藏布江中游高山灌丛植被的一种典型的非繁殖季节集群鸟类。野外观察表明 ,为了独享好的食物资源 ,一些个体常常远离当前群体的活动范围。分离事件更可能发生于大的群体 ,但其发生率与参与者的数量呈负相关 ;而参与分离的个体愈多 ,分离持续的时间就愈长。分离者的个体警惕水平随着临时群体大小的增加而下降 ,遵从在其它自然大小鸟类群体所发现的一般性规律。分离行为的发生和持续时间被认为是个体对当前食物回报和捕食风险进行权衡的结果。这种利益 -代价权衡也可以解释藏马鸡所具有的强烈集群行为     

Effects of habitat fragmentation on the genetic structure of the monophagous butterfly Polyommatus coridon along its northern range margin

Population genetic patterns of species at their range margin have important implications for species conservation. We performed allozyme electrophoresis of 19 loci to investigate patterns of the genetic structure of 17 populations (538 individuals) of the butterfly Polyommatus coridon, a monophagous habitat specialist with a patchy distribution. The butterfly and its larval food plant Hippocrepis comosa reach their northern distribution margin in the study region (southern Lower Saxony, Germany). Butterfly population size increased with host plant population size. The genetic differentiation between populations was low but significant (FST = 0.013). No isolation-by-distance was found. Hierarchical F-statistics revealed significant differentiation between a western and an eastern subregion, separated by a river valley. The combination of genetic and ecological data sets revealed that the expected heterozygosity (mean: 18.5%) decreased with increasing distance to the nearest P. coridon population. The population size of P. coridon and the size of larval food plant population had no effect on the genetic diversity. The genetic diversity of edge populations of P. coridon was reduced compared to populations from the centre of its distribution. This might be explained by (i). an increasing habitat fragmentation towards the edge of the distribution range and/or (ii). a general reduction of genetic variability towards the northern edge of its distribution.     

Effects of feeding regime on growth rate in the Mediterranean Sea anemone Actinia equina (Linnaeus)

Polyps of Actinia equina are the most common sea anemones in the rocky intertidal zone of the Mediterranean coast of Israel, where they occur in one of the southernmost populations of this species in the northern hemisphere. We examined effects of feeding rate on polyp growth at ambient sea temperature for this population. Under laboratory conditions, polyps were left unfed, or were fed with brine shrimp (Artemia) once every 2 weeks, once a week, or twice a week. Of the four experimental treatments, only feeding twice a week resulted in polyp growth; under all other regimes, the sea anemones lost body mass. We conclude that a high rate of feeding is required at sea temperatures in the eastern Mediterranean, where these sea anemones may have high metabolic rates relative to more northern populations.     

GENETIC AND SOCIAL INHERITANCE OF BODY AND EGG SIZE IN THE BARNACLE GOOSE (BRANTA LEUCOPSIS)

We present heritability estimates for final size of body traits and egg size as well as phenotypic and genetic correlations between body and egg traits in a recently established population of the barnacle goose (Branta leucopsis) in the Baltic area. Body traits as well as egg size were heritable and, hence, could respond evolutionarily to phenotypic selection. Genetic correlations between body size traits were significantly positive and of similar magnitude or higher than the corresponding phenotypic correlations. Heritability estimates for tarsus length obtained from full-sib analyses were higher than those obtained from midoffspring-midparent regressions, and this indicates common environment effects on siblings. Heritabilities for tarsus length obtained from midoffspring-mother regressions were significantly higher than estimates from midoffspring-father regressions. The results suggest that this discrepancy is not caused by maternal effects through egg size, nor by extra-pair fertilizations, but by a socially inherited foraging site fidelity in females.     

印度地鼠的性成熟和窝仔数

为有效地进行有害脊椎动物的控制 ,研究了栖息于巴基斯坦Punjab中部的 348只印度地鼠的繁殖模式。在所捕捉到的 10 7雄鼠和 2 4 1只雌鼠中 ,分别有 75只和 179只是性成熟的个体。性比偏雌。使用被捕个体标本的体重和体长作为指标 ,发现最小的性成熟的雄性个体体重为 70 - 89g ,体长 13 1- 14 0cm ;一窝仔里面的平均胚胎数为 2 74± 0 15 (范围 ,1- 5 ) ,而平均胎斑数为 4 2 9± 0 19(1- 11) .体重似乎对窝仔数有显著影响 ,而体长和估计的年龄对窝仔数没影响。当老鼠繁殖不活跃和不繁殖时 ,控制害兽最有效