Study on Chemosensitive Hairs in Wolf Spiders (Araneae, Lycosidae) by Scanning Electron Microscopy

The occurrence of chemosensitive hairs in some lycosid species is examined. The distribution and shape of such hairs dorsally on the male subadult palpal tarsus and the cymbium are compared. In certain species (e.g. of the genera. Pardosa and Alopecosa) the cymbium has a dense covering of these hairs while there are rather few of these in the male subadult palpal tarsus. The cymbium of Aulonia atbimana has comparatively few chemosensitive hairs dorsally, a condition supposedly related to the web-building habit in this species. Indications are given that the cymbial chemosensitive hairs are involved in the detection of presumed contact sex pheromones produced by the female. Certain intergeneric differences in the shape of the apical part of the cymbial chemosensitive hairs are noted.     

Features of the underwater light climate just below the surface in some New Zealand inland waters

1. Using sampling rates of 8–64 Hz we found clear indications of extensive and high frequency fluctuations of underwater photosynthetically active radiation (PAR) just below the surface (0.016–1.1 m) in some New Zealand water bodies. High variability and flashing occurred down to at least 3 m depth.
2. PAR variability increased under the influence of bright sunshine if wind roughening of the surface took place. Concomitantly, the average PAR levels declined by about 10%. However, even when the surface was shaded, high variability of PAR persisted.
3. Under a calm surface, PAR irradiance followed a log normal distribution. This occurred independently of the presence of direct sunlight. However, when the surface was roughened by wind in sunshine, PAR immediately switched to a Gumbel (extreme value type EV1) distribution.
4. Neither wave action nor wave focusing of incident irradiance would explain the wide range of PAR close to the water surface, although both factors add to the PAR variability.
5. The data indicate that transmittance through the surface is highly variable at the temporal and spatial scales studied, and that the irregularity of the air–water interface is instrumental in bringing about the observed fluctuations of PAR just below the surface.     

Colonization in metapopulations: a review of theory and observations

In metapopulation dynamics turnover of populations in isolated patches may be frequent. Regional survival of a species in such a system with frequent extinctions hinges on its colonization ability. Colonization is more than just dispersal; when a propagule reaches a new patch it faces higher extinction probabilities than does an established population. Extinction models as well as empirical data suggest that a large propagule with a potential for rapid increase in a varying environment, or with a low mortality rate in an environment perceived as constant, has a higher probability of successful colonization. Large variation in population size when it is still small increases the risk of failure. Factors introducing such variation are demographic stochasticity and environmental variation. It is hard to single out demographic traits that ensure good colonizing ability, since colonization can be achieved in many different ways, but generalists and species with self-fertilization seem to be superior.     

Using predictive models to estimate effects of flow regulation on net-spinning caddis larvae in North Swedish rivers

1. Effects of flow regulation on abundance and richness of net-spinning caddis larvae (Hydropsychoidea; Trichoptera) were examined in fifty-two North Swedish rivers. Models based on conditions at unregulated sites were used to predict densities at impacted sites and the residuals, i.e. the differences between observed and predicted numbers, were used as measures of the effects.
2. Two broad categories of impacted sites were identified. Sites with regulated but unreduced flow often have reduced seasonal flow variation and slightly enhanced short-term variation, while those with reduced flow usually have long periods of low and stable flow occasionally interrupted by short periods of violently fluctuating flow.
3. The abundance of net-spinning caddis larvae was significantly lower than predicted at both types of sites (reduction 30%), while richness was significantly reduced only at sites with reduced flow (reduction 20%).
4. A subsequent analysis of the relationship between the effects and variables altered by flow regulations, e.g. flow magnitude and flow variation, indicated that species richness was primarily affected by the occurrence of periods with zero flow, while negative effects of abundance were associated with high flow variability.
5. Significant negative effects on the abundance of individual taxa were observed for Cheumatopsyche lepida and Hydropsyche pellucidula at sites with regulated but unreduced flow.
6. Analyses of the relationships between the effects and regulation-related variables suggest that H. siltalai was significantly negatively affected by the occurrence of zero flow and that negative effects on Arctopsyche ladogensis were associated with flow reduction and high flow variability.     

Overwintering strategy of two closely related forms of Cloeon (dipterum?) (Ephemeroptera) from Sweden and England

SUMMARY. Comparison is made of resistance to anoxia at 0°C of an English and a Swedish winter larval population of two closely related forms of Cloeon (dipterum?). The English population was not very resistant but contained a few slightly resistant larvae; the Swedish population was very resistant. Swedish larvae initiated hibernation more rapidly than English larvae and were also more resistant to starvation. The different properties of the populations are seen as an adaptation to different winter conditions in ponds in England and Sweden. Evidence is presented that low temperatures but not decreasing photoperiod are decisive for the final induction of hibernation in the larvae. In Swedish larvae this induction starts at between 4 and 5°C.     

de novo转录组学分析华南地区入侵植物五爪金龙代谢特征

为探究华南地区严重入侵植物五爪金龙(Ipomoea cairica)生物入侵的分子机制,对五爪金龙及其近缘种七爪金龙(I. digitata)和裂叶牵牛(I. nil)进行de novo转录组测序和组装,得到56551条unigenes,其中56522条得到注释,7815条GO注释,15615条COG注释,180201条KEGG数据库注释。转录组分析结果表明,五爪金龙氮代谢通路关键酶基因的表达高于对照。次生代谢关键酶(PAL、4CL、CAD、查耳酮合酶、苯基丙乙烯酮异构酶、槲皮黄3-O-甲基转移酶等)基因在五爪金龙与七爪金龙及裂叶牵牛中均得到协同性的差异表达,而这些代谢通路指导的产物合成对五爪金龙的抗逆境能力、生长、化感作用等均起关键作用。关键基因的RT-qPCR验证结果与转录组结果具有一致性。因此,这从分子生物学层面上对解释五爪金龙在华南地区的入侵机制提供了新的证据。