Estimating plant responses to climate by direct gradient analysis and geographic distribution analysis

We characterised the climatic behaviour of 53 woody species in terms of the climatic factors that play the main role in controlling species distribution in the study area. Floristic and climatic data were obtained from 150 stands in sites under climatic control (i.e. eu-climatopes). The sampling strategy used allowed a reliable match between floristic and climatic observations. Different methods of frequency analysis and goodness-of-fit tests were used to identify associations between species occurrence and climatic characteristics. The species' responses were summarised by statistics describing ecological preferences and amplitudes, and species were grouped accordingly. A Gaussian response model was fitted to the abundance data along the main climatic gradients for selected species and response surfaces were derived by spatial analysis for a set of indicator species. Frequency analysis methods detected 42 indicator taxa for the Baudiere's Qe drought index, and lower numbers, 34 and 22, respectively, for the mean minimum coldest-month temperature and the daily temperature range in the coldest month. Goodness-of-fit tests revealed a lower number of ecological profiles with statistically significant deviations from equidistribution. We discuss the relative performance of the different methods and suggest that the combined use of statistical tests and frequency analyses may improve estimation of the environmental requirements of species. We also recommend using the species' responses to key environmental factors as reliable criteria in the definition of plant functional types. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of trap design, trap size and pheromone dose on male capture of two pine bast scales species (Hemiptera: Matsucoccidae): implications for monitoring and mass-trapping

Abstract 1 The effects of pheromone dose, trap size and trap design on the capture of male Matsucoccus feytaudi were studied in maritime pine forests of Portugal, France and Italy, and Matsucoccus josephi in Aleppo pine stands of Israel. 2 Males of both species respond to racemic mixtures of the respective sex pheromone at a dosage as low as 25 µg. However, for low population densities of M. feytaudi, a 50 µg dosage was needed to guarantee male catches significantly different from the control trap. 3 Male capture increased with increasing dosage up to a threshold level for both species. Overdose repellence was not observed even with baits containing 1600 and 2200 µg of the pheromone of M. josephi and M. feytaudi, respectively. 4 For M. feytaudi, a higher dose–response was observed at medium population densities, whereas lesser captures were registered at low and high population densities, suggesting female competition in the latter case. 5 Catches of M. feytaudi males were not affected by trap design, whereas M. josephi males were caught in significantly greater numbers in delta traps. Large traps caught significantly more males of both species. 6 The relative higher male catches in the marginal zone of the sticky traps is probably related to males landing behaviour in the vicinity of the pheromone source. 7 The shape and size of the trap did not affect the bias of the estimates of male catches. However, the plate traps provided higher precision. Both bias and precision improved with increasing dose.     

Antennal sucrose perception in the honey bee (Apis mellifera L.): behaviour and electrophysiology

Physiological mechanisms of antennal sucrose perception in the honey bee were analysed using behavioural and electrophysiological methods. Following sucrose stimulation of the tip of a freely moving antenna, the latency of proboscis extension was 320–340 ms, 80–100 ms after the first activity in muscle M17 controlling this response. When bees were allowed to actively touch a sucrose droplet with one antenna, contacts with the solution were frequent with durations of 10–20 ms and average intervals between contacts of approximately 40 ms. High sucrose concentrations led to short and frequent contacts. The proboscis response and M17 activity were largely independent of stimulus duration and temporal pattern. Taste hairs of the antennal tip displayed spike responses to sucrose concentrations down to at least 0.1%. The first 25 ms of the response were suitable for discrimination of sucrose concentrations. This time interval corresponds to the duration of naturally occurring gustatory stimuli. Sucrose responses between different hairs on the same antenna showed a high degree of variability, ranging from less than five to over 40 spikes per 0.5 s for a stimulus of 0.1% sucrose. This variability of receptor responses extends the dynamic range of sucrose perception over a large range of concentrations.     

Interactions between a hunting spider and a web-builder: consequences of intraguild predation and cannibalism for prey suppression

Abstract. 1. Antagonistic interactions among invertebrate predators such as intraguild predation and cannibalism have the potential to dampen top‐down impacts on shared prey at lower trophic levels. Two abundant spider predators, the large wolf spider Pardosa littoralis and the small sheet‐web builder Grammonota trivitatta co‐occur on the salt marshes of eastern North America where they both attack planthoppers (Prokelisia spp.), the dominant herbivores on the marsh. Experiments both in the laboratory and field were used to assess the incidence of intraguild predation and cannibalism in these spiders and elucidate how such antagonistic interactions influence planthopper suppression. 2. Functional response experiments showed that with an increase in planthopper prey density, Grammonota captured more prey but not a higher proportion of that offered. Pardosa exhibited the same response when Grammonota were offered as intraguild prey. Both functional responses were type I over the range of prey densities offered. 3. Grammonota is moderately cannibalistic, and the presence of planthopper prey reduced the incidence of cannibalism. 4. Factorial experiments in the laboratory showed that Pardosa but not Grammonota reduced planthopper prey populations when prey density was low. By contrast, at high prey densities, both Pardosa and Grammonota had significant adverse effects on planthopper populations. Moreover, there was an interactive effect such that Grammonota reduced planthopper populations relatively more when Pardosa was absent than when it was present. 5. There was direct evidence for the intraguild predation of Grammonota by Pardosa such that fewer Grammonota survived in the presence of Pardosa than when it was absent. This result occurred whether planthopper prey were abundant or not. 6. Field releases of Grammonota in open plots resulted in significant but small decreases in the density of planthopper prey, both nymphs and adults. 7. Enhancing densities of Pardosa in open plots resulted in Grammonota suppression. The intraguild predation of Grammonota at this enhanced Pardosa density, however, did not preclude Pardosa from significantly reducing planthopper populations. 8. Although there was evidence that Grammonota reduced planthopper populations and that the intraguild predation of Grammonota by Pardosa occurred, the strength of these interactions was relatively weak given the low consumption rate of planthoppers by Grammonota (< 3 day^–1) and Grammonota by Pardosa (≈ 2 day^?1). Thus, weak asymmetric intraguild predation among spiders on the marsh likely dampens but does not eliminate the ability of Pardosa to exert significant top‐down control on planthopper populations.     

Effects of Temperature on the Early Development, Growth, and Survival of Shortnose Sturgeon, Acipenser brevirostrum, and Atlantic Sturgeon, Acipenser oxyrhynchus, Yolk-Sac Larvae

We reared shortnose and Atlantic sturgeons at different temperatures after hatch and measured yolk utilization rate and efficiency (YUE), maximum standard length, survival and development of escape response. Newly hatched Atlantic sturgeon, were smaller in size, more efficient at utilizing yolk (incorporating yolk to body tissue) and reached developmental stages sooner than shortnose sturgeon reared at the same temperatures (13–15°C). Within each species, decreasing temperature delayed yolk absorption, escape initiation, time to reach maximum size, and time to 100% mortality. However, YUEs and the size of the larvae at these 'stages' were independent of rearing temperature for both species. These results suggest that even as temperature drives metabolic processes to speed up development, these two species are still extremely efficient at transferring yolk energy to body tissues. The lower efficiencies experienced by larval shortnose may reflect difference in yolk quality between the two species and/or the Atlantic sturgeon's higher conversion efficiency. The ability of these two sturgeon species to develop successfully and efficiently under a wide range in temperatures may provide a competitive advantage over more stenothermic species and explain their persistence through evolutionary time.     

绿豆插条生根过程中内源激素含量变化

绿豆插条离体后其IAA含量出现一个峰值,乙烯利处理的IAA峰值出现在第6小时,未经乙烯利处理的出现在第12小时,与插条生根峰出现时间相符.乙烯利处理与否的插条生根过程中,内源GA3含量在0～30h内呈下降趋势,随后略微上升;内源ABA含量先升后降;细胞分裂素ZT和ZR含量在总体上是下降的.     

佩妃延腹榕小蜂的产卵行为

榕树与传粉榕小蜂之间的互惠共生关系是协同进化研究领域中的热点之一。榕树除了与传粉榕小蜂共生外,它还为许多非传粉榕小蜂提供食物和生境。佩妃延腹榕小蜂Philotrypesis pilosa Mayr腹部第8～9节背板极度延伸,形似长长的产卵鞘,其后更长的才是真正的产卵鞘。它将产卵针刺入榕果的果壁,产卵于果内。该蜂是对叶榕Ficus hispida L. 的传粉榕小蜂Ceratosolen solmsi （Mayr）的盗食性寄生蜂。我们利用数码照相机记录了佩妃延腹榕小蜂产卵的全过程,详细描述了其产卵行为。发现了前人没有发现的下列行为特点： (1）当雌蜂找到合适的产卵位点时,身体呈倒立状,后足扶持产卵鞘到选定的产卵位点;2）从开始插入产卵针到产卵鞘向后弹出,腹部第8～9节背板延伸部分与产卵鞘之间有两次大幅度的靠拢与分开,第一次靠拢与分开是保证产卵针以最佳的垂直角度插入果内,第二次是使产卵鞘向后弹出,将暴露在外的产卵针顺利地插入果内;3）雌蜂产卵针沿榕果直径方向（最短距离）插入果壁;4）前足与后足比中足发达,与整个产卵过程中支撑身体的行为有关 。     

NO和NADPH-黄递酶在绿豆下胚轴不定根发生和发育过程中的变化(英文)

研究了一氧化氮(NO)供体硝普钠(SNP)、一氧化氮清除剂c-PTIO和一氧化氮合酶(NOS)抑制剂L-NAME对绿豆(Vigna radiata L.)下胚轴插条生根的影响,并对不定根发生期间插条基部NO和NADPH-黄递酶的时空变化进行了检测。所试浓度SNP均明显促进下胚轴不定根发生。分别在插条切取后24 h和36 h于其基部维管束之间检测到NADPH-黄递酶(NOS标记酶)阳性反应和NO荧光,根原基也于48 h在相同位置出现,并于60 h进一步伸长。48-60h期间,NADPH-黄递酶的阳性反应及NO荧光有增强趋势,并主要分布在不定根分生组织中。L-NAME既减弱NADPH-黄递酶的阳性反应和NO荧光,也延缓不定根发生;而c-PTIO对NO荧光及不定根发生均有抑制作用。上述结果证明:NO在不定根发生及发育过程中有重要作用,而且此过程中的NO很可能由类似的NOS催化产生。     

新疆塔里木河下游生态输水与胡杨叶片的生理及形态响应

选择塔里木河下游3个典型断面的15个研究样地,分析和测定了塔里木河下游2000￣2002年生态输水前后不同研究样地的地下水位、地下水含盐量和胡杨(Populus　euphratica　Oliv.)叶片中脯氨酸、可溶性糖、植物内源激素脱落酸和细胞分裂素的含量以及胡杨叶片的形态结构变化,研究了塔里木河下游主要建群种胡杨对生态输水的生理与形态的响应和适应性。结果表明,塔里木河下游胡杨生长已受到不同程度的干旱胁迫;输水后各样地地下水位均有所上升,胡杨对浅层地下水位的变化表现出明显响应,胡杨受到的生理胁迫降低,胡杨叶片角质层厚度、维管束导管官腔直径及管壁厚度皆随地下水位的上升而减少;随着地下水位的上升,地下水含盐量分别提高1.76　￣　2.47倍,输水效果由于盐对植物的生理胁迫作用的增加而有所减弱;在塔里木河下游极端干旱环境下,胡杨林保育恢复的合适地下水位埋深为3.15　￣　4.12　m,地下水含盐量为67.15　￣　72.65　mm。     

Predatory behavior and preference of a successful invader, the mud crab Dyspanopeus sayi (Panopeidae), on its bivalve prey

Predator-prey relationships between the panopeid crab, Dyspanopeus sayi, and the mytilid, Musculista senhousia, were investigated. Through laboratory experiments, prey-handling behavior, prey size selection, predator foraging behavior and preferences for two types of prey (M. senhousia and the Manila clam Ruditapes philippinarum) were assessed. Handling time differed significantly with respect to the three prey sizes offered (small: 15.0-20.0 mm shell length, SL; medium: 20.1-25.0 mm SL; and large: 25.1-30.0 mm SL); mud crabs were more efficient in predating medium-small than large prey. Although differences in prey profitability were not evident, D. sayi exhibited a marked reluctance to feed on larger-sized prey whilst smaller, more easily predated mussels were available. Size selection may be the result of a mechanical process in which encountered prey are attacked but rejected if they remain unbroken after a certain number of opening attempts. D. sayi exhibited inverse density-dependent foraging. A significant higher mortality of prey was evident at low prey density. Thus, at low predator density, the D. sayi-M. senhousia interaction was a destabilizing type II functional response. Interference responses affected the magnitude of predation intensity by D. sayi on M. senhousia, since as the density of foraging crabs increased, their foraging success fell. At high density (4 crabs tank⁻¹), crabs engaged in a high amount of agonistic activity when encountering a conspecific specimen, greatly diminished prey mortality. Finally, presenting two types of prey, Manila clam juveniles were poorly predated by mud crabs, which focused their predation mostly on M. senhousia. It is hypothesized that, when more accessible prey is available, mud crabs will have a minimal predatory impact on commercial R. philippinarum juvenile stocks.