异色瓢虫幼虫的食物搜索行为

本试验采用Nakamuta(1982)装置研究两种光照条件下异色瓢虫幼虫的食物搜索行为,结果表明：(1)摄食刺激均能激发搜索行为由广域型转换为地域集中型;(2)摄食时间越长,地域集中型搜索时间(GUT)值越大;(3)摄食的最后一个食饵大小决定GUT的长短;(4)光照对搜索行为有影响;(5)饥饿度对GUT的长短有一定影响。     

异色瓢虫雌成虫的食饵搜索行为

本试验采用Nakamuta（1982）装置研究两种光照条件下异色瓢虫雌成虫的食饵搜索行为,结果表明：1、五种刺激均能激发搜索行为由广域型转换为地域集中型;2、摄食时间越长,GUT值越大;3、摄食的最后一个食饵大小决定GUT的长短;4、光照对搜索行为影响不大．     

龟纹瓢虫成虫的食饵搜索行为——向地域集中型转换的激发和持续时间

为了研究在15—25lux和230—280lux两种光照条件下雌雄龟纹瓢虫成虫搜索行为转换的因子及作地域集中型搜索持续的时间(giving-up-time——简写为GUT)长短,按Nakamuta(1982)方法给予以下五种刺激:a.和棉蚜接触;b.捕获棉蚜或仅食去撕去量;c.完全吃下捕获的1头棉蚜;d.和琼脂块(2×2×2mm)接触;e.吃下沾有棉蚜体液的琼脂块(2×2×2mm)。以不给予刺激作对照,观察每种刺激对搜索行为转换的激发作用。结果表明五种刺激的任一种刺激都可激发搜索行为的转换。结果还表明GUT值随刺激程度大小而变化,其大小顺序为a=d相似文献   

异色飘虫雄成虫的食饵搜索行为

研究两种光照条件下异色飘虫雄成虫的食饵搜索行为．结果表明,５种刺激均 能激发搜索行为由广域型转换为地域集中型;摄食时间越长,ＧＵＴ值越大;摄食的最后一 个食饵大小决定ＧＵＴ的长短;光照强度对搜索行为影响不大．     

异色瓢虫雄成虫的食饵搜索行为

研究两种光照条件下异色瓢虫雄成虫的食饵搜索行为。结果表明：５种刺激均能激发搜索行为由广域型转换为地域集中型;摄食时间越长,ＧＵＴ值越大,摄食的最后一个食饵大小决定ＧＵＴ的长短,光照强度对搜索行为影响不大。     

异色飘虫成虫的限域搜索行为

对异色瓢虫雌、雄成虫在摄食前后的限域搜索行为的研究表明,摄食前后０~１５ｓ内搜索行为轨迹弯曲角度总和之间差异显著,摄食后显著大于摄食前,其搜索活动频繁地作方向变换,以此提高搜索效率;摄食前后０~１５ｓ、１５~３０ｓ、３０~４５ｓ内的各对应停点距离差异显著,摄自前各停点间距离显著大于摄食后;摄食前后０~１５ｓ、１５~３０ｓ、３０~４５ｓ搜索速度,摄自前是摄食后的４~１２倍,摄自前搜索速度变化很小,而摄食后离摄自的时间越长,搜索速度越快;摄食点到停点的直线距离,摄食前后之间差异显著,摄食前显著大于摄食后,若按面积范围比较,摄食前是摄食后的１１~６５倍．可以认为,异色瓢虫雌、雄成虫均具有限域搜索行为．     

异色瓢虫若虫的限域搜索行为

在Ｎａｋａｍｕｔａ装置中,通过对两种我照照条件下（强光照３６８０－４６２０ｌｘ,弱光照１３０－２２０ｌｘ）异色标虫若虫搜索麦蚜行为轨迹的研究,得出摄食麦蚜前后０－１５ｓ搜索行为轨这弯曲角度总和之间差异均显著,摄食后大于摄前;摄食麦蚜前后０－１５ｓ、１５－３０ｓ、３０－４５ｓ、４５－６０ｓ内的各对应停点间距离差异均显著,摄食前大于摄食后;其搜索速度,摄食前显著大于摄食后。     

囊鼠某些摄食行为的观察(英文)

囊鼠是一种营地下单洞穴居的鼠类,广泛分布于加利福尼亚州的农田、牧场和森林,危害甚大。作者在实验室条件下对两种襄鼠(Thomomys bottae和Thomomys mazama)的某些摄食行为进行了观察,得到以下结论: 1.囊鼠的摄食行为有8个组成部分,即:(1)暴露洞口;(2)探察洞外动静;(3)将食物拖入洞内;(4)储藏食物;(5)反复在洞外搜索剩余食物;(6)推土堵洞;(7)尝试及摄食;(8)对粪便和尿的处理。     

不同饲养条件下海南坡鹿幼体春季昼间行为时间分配及活动节律

2003 年2 月至4 月间, 在海南甘什岭自然保护区采用瞬时扫描取样法对10 头海南坡鹿幼体昼间行为时间分配和活动节律进行了初步研究。结果表明: 坡鹿幼体昼间行为时间分配中摄食、卧息和反刍占有较大的比例;人工圈养和半散放条件下摄食、卧息、反刍、站立和运动行为的昼间时间分配差异性显著( P < 0.01), 半散放条件下幼鹿每天用于摄食和运动的时间比人工圈养的多, 而用于卧息、反刍和站立的时间较少, 其余行为时间比较接近; 在昼间活动节律方面, 圈养条件下摄食有3 个高峰期(09:00～10:00, 11:00～12:00, 16:00～18:00) , 卧息有2 个高峰期(10:00～11:00, 13:00～16: 00) ; 半散放条件下没有明显的摄食高峰期, 主要原因是大部分时间花费在食物的搜索和处理上, 而其卧息高峰出现在14:00 以后。     

具有捕食正效应的捕食-食饵系统

在经典的捕食食饵系统中考虑到由于捕食效应对食饵种群带来的正向调节作用后,提出了具有捕食正效应的捕食-食饵系统.通过对模型的动力学行为的分析,从理论上说明了正向调节作用对系统的影响,并就第一象限内平衡点存在时的相图解释了捕食正效应的作用.结果表明:(1)捕食系统中适当的正向调节作用会增加系统的稳定性;(2)当捕食正效应达到一定的程度后系统拥有一个不稳定的极限环;(3)当捕食正效应过大时会使系统的稳定性发生变化,使捕食者种群与食饵种群同时趋向无穷,出现了调节放纵现象.这些结果在保护生物学中具有重要的意义.     

Equilibrium flock size and factors affecting arrival and departure in feeding house sparrows

One way in which the size of flocks of sparrows feeding on barley seed was found to be limited was through the attainment of an equilibrium flock size (EFS). The two most important factors influencing the EFS were the size of the densest patch of seed at a feeding site and seed density outside the patch. Birds appeared to arrive at random but to depart in response to a giving up time (GUT) the length of which was positively related to preceding interpeck intervals. The GUT correlates best with the average interval for the last three pecks before leaving. The rate of fighting per bird increased with flock size. Some birds remained behind when others left and appeared to be those whose low peck rate increased when other birds left.     

Genetic compatibility between sexual and clonal genomes in local populations of the hybridogeneticRana esculenta complex

Summary Hybridogenetic species possess a hybrid genome: half is clonally inherited (hemiclonal reproduction) while the other half is obtained each generation by sexual reproduction with a parental species. We addressed the question of whether different hemiclones of the hybridogenetic water frogRana esculenta are locally adapted for genetic compatibility with their sexual parental hostRana lessonae. We artificially crossedR. esculenta females of three hemiclones (GUT1, GUT2 and GUT3) from a pond near Gütighausen, Switzerland and one hemiclone (HEL1) from near Hellberg, Switzerland each toR. lessonae males from both populations. We also created primary hybrids by crossing the sameR. lessonae males from both populations toR. ridibunda females from Pozna, Poland (POZ). Tadpoles were then reared in the laboratory at two food levels to assess their performance related to early larval growth rate, body size at metamorphosis and length of the larval period. Tadpoles from hemiclones GUT1, GUT3 and POZ had higher growth rates than those from hemiclones GUT2 and HEL1 at the low food level, but at the high food level all growth rates were higher and diverged significantly between hemiclones GUT2 and HEL1. Tadpoles from the intrapopulational crosses GUT2 × GUT and HEL1 × HEL were larger at metamorphosis than those from the interpopulational crosses GUT2 × HEL and HEL1 × GUT. A high food level increased the size at metamorphosis in all tadpoles. A high food level also decreased the days to metamorphosis and tadpoles from GUT1, GUT3 and POZ had the shortest larval period whereas those from GUT2 and HEL1 had the longest. These results indicate that the differential compatibility of clonal genomes may play an important role in hybridogenetic species successfully using locally adapted sexual genomes of parental species and that interclonal selection is likely important in determining the distribution of hemiclones among local populations.     

COMPETITION AMONG TADPOLES OF COEXISTING HEMICLONES OF HYBRIDOGENETIC RANA ESCULENTA: SUPPORT FOR THE FROZEN NICHE VARIATION MODEL

Vertebrate animals reproducing without genetic recombination typically are hybrids, which have large ranges, are locally abundant, and live in disturbed or harsh habitats. This holds for the hemiclonal hybridogenetic frog Rana esculenta: it is widespread in Europe and commonly is found in disturbed habitats such as gravel pits. We hypothesize that its widespread occurrence may either be the result of natural selection for a single hemiclone acting as a broadly adapted “general-purpose” genotype, or of interclonal selection, which maintains multiple hemiclones that each are relatively narrowly adapted and perform differently across environments, that is, the Frozen Niche Variation model. We tested these competing hypotheses using 1000-L outdoor artificial ponds to rear tadpoles of the parental species (Rana lessonae [LL] and Rana ridibunda [RR]) alone, and each of three hemiclones of Rana esculenta (GUT1, GUT2, GUT3) alone, and in mixed hemiclonal populations from hatching to metamorphosis. Tadpoles of three coexisting hemiclones from a single natural population (near Gütighausen, Switzerland) were reared in both two- and three-way mixtures in equal total numbers at high and low density. For each species and hemiclone, the proportion of tadpoles metamorphosing decreased as the density of tadpoles increased, with the three hemiclones spanning the range of values exhibited by the two parental species. LL and GUT1 tadpoles produced the highest proportion of metamorphs, whereas tadpoles of RR produced the fewest metamorphs at both densities. GUT1 tadpoles also produced the largest metamorphs at low density, GUT2 and GUT3 tadpoles produced smaller metamorphs than did GUT1 tadpoles at the low density, but the three hemiclones did not differ from each other at high density. The parental species (LL and RR) were intermediate in metamorphic size to the hemiclones at low density, but all genotypes converged on a similar size at high density. Length of the larval period also was affected by density, but its effect was dependent on genotype. GUT1 tadpoles had the shortest larval period at the low density, but larval period was longer and not different between GUT1, GUT3, and LL at high density. RR tadpoles had the longest larval period at both densities. The most dramatic results were that three genotypes (GUT1, GUT2, and RR) maintained rank order and increased days to metamorphosis from low to high density, whereas two genotypes (GUT3 and LL) changed rank order and decreased days to metamorphosis from low to high density. Mixtures of hemiclones in two- and three-way combinations facilitated the proportion of tadpoles metamorphosing for GUT1 and GUT2 at both densities, but only at the low density for GUT3 tadpoles. Results from this experiment are incompatible with the General-Purpose Genotype model as a global explanation of hybrid abundance in these frogs. Alternatively, the Frozen Niche Variation prediction of general performance superiority of clonal mixtures relative to single clone populations is strongly supported. The data confirm that fitness advantages of hemiclones change, depending on the environment, such that in temporally and spatially heterogeneous habitats like ponds, frequency-dependent selection among hemiclones may promote coexistence in hemiclonal assemblages. Yet, differential dispersal or colonization ability and historical factors affecting hemiclone distribution may also be important in shaping patterns of clonal coexistence.     

Cloning and characterisation of the Saccharomyces cerevisiae glycerol-3-phosphate dehydrogenase (GUT2) promoter.

The Saccharomyces cerevisiae glycerol-3-phosphate dehydrogenase (GUT2) promoter and part of the protein-coding region have been isolated on a 6.3-kb genomic DNA fragment. Nucleotide sequence analysis shows that the promoter has many structural features in common with yeast glycolytic enzyme promoters. Chromosomal mapping indicates that this genomic fragment is located on chromosome XII. The GUT2 promoter has been used to construct a recombinant human albumin (reHA) secretion vector; yeast transformed with this vector secrete reHA into the culture supernatant.     

Influence of intrapatch experiences and temperature on the time allocation of the whitefly parasitoidEncarsia formosa (Hymenoptera: Aphelinidae)

The effect of experiences, such as contact with honeydew, rejections of hosts, and ovipositions in hosts, and of temperature on the time allocation of individualEncarsia formosa female parasitoids on tomato leaflets have been studied. Behavioral records were analyzed by means of the proportional hazards model. Analyses were carried out at two levels: (1) the tendency of leaving and (2) the tendency of changing from one leaf side to another. The patch-leaving behavior ofE. formosa can be described by a stochastic threshold mechanism, which is characterized by a certain tendency (probability per time) to leave. The median time from being placed on the leaflet or, if it occurred, from the latest encounter with a host until leaving was 18.6 min. The median time for changing from one leaf side to the other was initially 11.6 min and dropped to 5.7 min after both leaf sides had been visited. The effect of temperature, ranging from 20 to 30°C, was negligible. The presence of honeydew as well as the first oviposition in an unparasitized host decreased the tendency to leave, thus increasing the giving up time (GUT) since the latest encounter with a host. Encounters with parasitized hosts did not affect the GUT since latest encounter; as a result, the total residence time increased. After the first oviposition in an unparasitized host the tendency of changing from the lower leaf side on which hosts were present to the upper side was decreased. The presence of honeydew did not affect the tendency of changing leaf sides.     

Improvement in Oil Production by Increasing Malonyl-CoA and Glycerol-3-Phosphate Pools in Scenedesmus quadricauda

In recent years, microalgae have attracted considerable interest as a biofuel resource owing to their rapid growth, tolerance to harsh conditions, and ability to accumulate a large amount of triacylglycerols (TAGs). However, the economic effectiveness of algal biofuel is still low. In this study, we attempted to increase oil production of the microalga Scenedesmus quadricauda by elevating intracellular malonyl-CoA and glycerol-3-phosphate (G3P) pools. To increase intracellular oil content, yeast-derived genes encoding acetyl-CoA carboxylase (ACC1), glycerol kinase (GPD1), and glycerol-3-phosphate dehydrogenase (GUT1) were overexpressed under the control of CaMV 35S and NOS promoters with SV40 large T antigen components. Fatty acid profiling, G3P content, and the number of cells with high oil content were analyzed by gas chromatography-mass spectrometry, G3P assay kit, and flow cytometry, respectively. Overexpression of ACC1 increased the total fatty acid content by 1.6-fold. Overexpression of GPD1 and GUT1 increased intracellular G3P content by 1.6- and 1.9-fold, respectively. Multi-gene expression of ACC1, GPD1, and GUT1 increased the number of cells with high oil content by 1.45-fold compared with that observed with the wild-type. This study is the first to report increased oil production by overexpression of the key genes (ACC1, GPD1, and GUT1) for TAG biosynthesis in microalgae.

Electronic supplementary material

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