Spatial distribution of mitochondrial and microsatellite DNA variation in Daubenton's bat within Scotland

Daubenton's bat ( Myotis daubentonii ) is a known reservoir for European bat lyssavirus type 2 (EBLV-2). An appreciation of the potential for epidemiological spread and disease risk requires an understanding of the dispersal of the primary host, and any large-scale geographical barriers that may impede gene flow. The spatial pattern of microsatellite and mitochondrial DNA variation was examined to infer patterns of dispersal of bats among 35 populations across Scotland. DNA sequence variation at the mitochondrial control region and ND1 genes revealed two distinct phylogeographical clades, with generally nonoverlapping geographical distributions except for a small number of populations where both matrilines were found in sympatry. Such discontinuity suggests that Scotland was recolonised twice following the retreat of the Pleistocene ice sheet with little subsequent matrilineal introgression. However, eight microsatellite loci showed low levels of genetic divergence among populations, even between populations from the two distinct mitochondrial DNA clades. An overall, macrogeographical genetic isolation-by-distance pattern was observed, with high levels of gene flow among local populations. Apparently contrasting patterns of mitochondrial and microsatellite divergence at different scales could be explained by sex-specific differences in gene flow at large scales.     

Population density of the greater mouse-eared bat (Myotis myotis), local diet composition and availability of foraging habitats

We studied the regional variation in population density of Myotis myotis (Borkhausen 1797) in south-eastern Bavaria, Germany, and its relations to diet composition and the availability of potential foraging habitats. We monitored colony size and juvenile mortality from 1991 to 2003, conducted faecal analyses in 1993 and determined land-use patterns around colonies. The numbers of individuals counted in the nursery colonies showed only small fluctuations over the years. However, data on colony size demonstrated a pronounced regional variation. Epigeic arthropods, mainly Carabidae, were the most important prey. The diet included prey taxa of forest as well as grassland habitats. The percentage of those prey taxa in the diet that originated in grassland managed with different intensity varied according to the availability of these potential foraging habitats around the nursery roosts. The calculated population density of the bats was positively correlated to forest area and especially to the area of mixed forest around the nursery roosts. Our results indicate that the availability of foraging habitats is a limiting factor for local population densities in the greater mouse-eared bat.     

A stable isotope study of linkages between stream and terrestrial food webs through spider predation

SUMMARY 1. Transfer of carbon from freshwater to terrestrial ecosystems can occur through predation on adult aquatic insects, but the significance of this trophic pathway to the energetics of riparian communities is poorly understood. We used stable isotopes of carbon and nitrogen to explore linkages between aquatic insect production and the nutrition of web‐building and free‐living spiders alongside two streams in the North Island of New Zealand. 2. δ¹³C values for riparian tree leaves (means for each site = ?32.2 and ?30.3‰) were distinct from those of lichens collected from stream channel rocks and instream algae, both of which were similar (?23.4 to ?22.4‰). δ¹⁵N values for leaves were similar at both sites (?3.4 and ?2.7‰), but algae were considerably more depleted in δ¹⁵N atonesite suggesting significant differences in instream nitrogen sources between the twostreams. 3. Isotope values for potential aquatic prey of spiders indicated that aquatic algal production was their primary carbon source at both sites. Terrestrial invertebrates collected and assumed to be potential prey reflected a range of carbon sources and represented several trophic levels. 4. At one site, δ¹³C values indicated a primarily algae‐aquatic insect pathway of carbon transfer to both web‐building and free‐living spider guilds. The other site appeared to have a primarily terrestrial carbon pathway for the free‐living spider guild, and a mixed aquatic‐terrestrial pathway for the web‐building guild. 5. Overall, web‐building spiders were estimated to obtain around 61% of their body carbon from aquatic production compared with 55% for free‐living spiders. Our findings suggest that consumption of prey derived from aquatic sources can provide significant nutrition for spiders living along some stream channels. This pathway may represent an important feedback mechanism contributing to the energetics of riparian communities at sites where aquatic insect production is high.     

Aquatic invertebrates in riverine landscapes

1. Riverine systems consist of a mosaic of patches and habitats linked by diverse processes and supporting highly complex communities. Invertebrates show a high taxonomic and functional diversity in riverine systems and are in several ways important components of these systems. Their distribution patterns, movements and effects on ecological flows, testify to their importance in various landscape ecological processes. This paper reviews the invertebrate literature with respect to patterns and processes in the riverine landscape. 2. The distribution of invertebrates in riverine habitats is governed by a number of factors that typically act at different scales. Hence, the local community structure can be seen as the result of a continuous sorting process through environmental filters ranging from regional or catchment‐wide processes, involving speciation, geological history and climate, to the small‐scale characteristics of individual patches, such as local predation risk, substratum porosity and current velocity. 3. Dispersal is an important process driving invertebrate distribution, linking different ecological systems across boundaries. Dispersal occurs within the aquatic habitat as well as into the terrestrial surrounding, and also over land to other waterbodies. New genetic techniques have contributed significantly to the understanding of aquatic invertebrate dispersal and revealed the importance of factors such as physical barriers, synchrony of emergence and taxonomic affiliation. 4. Invertebrates affect the cycling of nutrients and carbon by being a crucial intermediate link between primary producers, detritus pools or primary consumers, and predators higher up in the trophic hierarchy. Suspension feeders increase the retention of carbon. The subsidies of aquatic invertebrates to the terrestrial ecosystem have been shown to be important, as are reciprocal processes such as the supply of terrestrial invertebrates that fall into the water. 5. Future studies are needed both to advance theoretical aspects of landscape ecology pertaining to the invertebrates in riverine systems and to intensify the experimental testing of hypotheses, for example with respect to the scaling of processes and to linkages between the terrestrial and aquatic systems. Another promising avenue is to take advantage of naturally steep environmental gradients, and of systems disturbed by humans, such as regulated rivers. By comparison with unimpaired reference sites, the mechanisms involved might be identified. The use of `natural' experiments, especially where environmental gradients are steep, is another technique with great potential.     

干热河谷麻疯树访花昆虫及主要传粉昆虫

膏桐为一种重要的油料作物,其种子可以提炼生物柴油,生物柴油在我国将成长为有一定规模的产业。为了增加膏桐结籽率,提高其产量,给膏桐规模化栽培方面提供传粉生物学的科学依据,于2006年对云南元江坝区半栽培膏桐(Jatropha curcas L.)居群的访花昆虫及主要传粉昆虫种类进行调查。膏桐开花示样醒目,具花香与蜜腺,花形态没有特化,这些特征使得它提供的酬物适合于不同的昆虫采食,其访花昆虫种类较丰富,共有35种访花昆虫,分属5目20科。综合访花昆虫的传粉数量,及传粉质量包括访花行为、访花频率与日活动规律等确定主要传粉昆虫,确定大头金蝇Chrysomya(Compsomyia)megacephala Fabricius、中华蜜蜂Apiscerana Fabricius、迁粉蝶(淡色型)Catopsilia pomona f.Crocale为该居群的主要传粉昆虫。3种传粉昆虫具有不同的访花习性和日活动规律。雌雄迁粉蝶日活动规律相似。访花者的组成受气象因素、开花示样及生境条件的影响。最后,探讨膏桐与访花昆虫的关系,以及主要传粉者的组成随时空变异而改变的规律。     

两种鼠耳蝠回声定位叫声的比较

对鼠耳蝠属两种蝙蝠飞行状态下的声发射进行了比较研究.结果表明两种鼠耳蝠声发射信号的声谱图都呈调频(FM)型,但在波形及频率范围上有明显差异.大鼠耳蝠(四川亚种)的声脉冲宽度很小(1.6±0.3ms),能率环较低(4.0%),其主频率(DF=44.6±4.3kHz)也较低;而水鼠耳蝠的声脉冲宽度较大(4.2±1.6ms),能率环(9.6%)及主频率(DF=83.0±4.0kHz)也较高.文中结合两种蝙蝠的形态及食性分析了回声定位对捕食生境及捕食策略的适应性.     

The effect of long pools on the drift of macro-invertebrates in a mountain stream

Macro-invertebrate drift was measured entering and leaving two pools on the Middle Fork of the Cosumnes River, a third order California stream. Drift rates for Baetis spp., Chironomidae, Simulium spp., Capniidae and total drift were calculated. Significant differences in the numbers of organisms entering the two pools were found for Baetis, Chironomidae, and Capniidae. Comparisons of drift rates at the upstream and downstream ends of each pool showed that the abundance of Chironomidae, Simulium, Capniidae and total drift changed in different directions across the pools. The numbers of organisms leaving the two pools, however, were not significantly different for Baetis, Simulium, Capniidae and total drift. These findings lead us to hypothesize that long pools act as barriers, not filters, to stream macro-invertebrate drift. The composition of drift leaving the pools in this experiment appeared to be controlled by the composition of the benthic habitat at the tail of the pool and not by the composition of upstream drift entering the pools.     

拖网式食鱼蝠——大足鼠耳蝠的形态、回声定位声波及捕食策略

大足鼠耳蝠(Myotisricketti)是中国特有蝙蝠,其回声定位声波和捕食策略国内外均无报道,对大足鼠耳蝠该方面的研究报导是国内首次。大足鼠耳蝠体型较大,具有强大的后足,足上有强而有力的弯曲的爪,尾膜和距很长。大足鼠耳蝠回声定位声波为FM(调频)型,一般具有1～2个谐波,主频率较低(37.78±1.04kHz),调频带较宽(第一谐波频带宽为42.02±6.98kHz,第二谐波频带宽为25.79±7.89kHz),声脉冲时间较长(2.91±0.54ms),声脉冲间隔时间变化较大(32.30±15.10ms),能率环较高(11.27±5.84%);野外观察发现,大足鼠耳蝠主要在低水面上空飞行,利用大足从水面捕食猎物(拖网式捕食),猎物主要由鱼类组成。即分析和讨论了大足鼠耳蝠形态特征、回声定位特征和捕食策略的相互适应性。     

An Attraction Pheromone from Heads of Worker Vespula germanica Wasps

Vespula germanica is a social wasp that efficiently exploits food resources. Odor cues, derived from substances located in wasp heads, have been proved to be central in conspecific attraction in this species. However, it remains unknown whether this attraction is related to foraging or defense responses. In this study we analyze conspecific attraction under two different contexts: at the nest entrance (defense) and under foraging conditions. We also test wasp response with two dosages of head extract and crosschecked the attractiveness of extracts obtained from different populations. We found no evidence of alarm response to head extracts either at the nest entrance or under foraging conditions. Moreover, no differences in attractiveness were found to both doses tested. Head extracts attract similarly in the same or a different population suggesting that conspecific attraction is not restricted to colony nestmates.     

Do pools impede drift dispersal by stream insects?

1. Drift of stream insects is one of the most ubiquitous forms of downstream dispersal and thought to be a key factor influencing the persistence of local populations. Identifying the factors that limit drift dispersal between habitat patches is needed to understand the connectivity of insect populations along river channels.
2. We determined whether insects drifting between riffle habitats (i.e. patches of suitable habitat) were impeded by natural, slow‐moving pools (i.e. unsuitable habitat), limiting dispersal to the next downstream riffle, by estimating drift rates entering and exiting pools. We also investigated whether the frequency of drift dispersal between riffle habitats decreased with increasing pool size (length, width and depth), resulting from increasing areas of low or zero current velocity and/or distance between habitat patches.
3. We found that for the majority of study taxa (7 of the 8 taxa), drift dispersal between riffles was significantly hindered by the intervening pool habitat, supporting our prediction that natural, large slow‐moving pools impede the number of invertebrates drifting between riffle habitats. There were three taxa whose drift rates were significantly reduced by increasing pool depth or width—Offadens hickmani, Austrophlebioides spp. and Austrosimulium spp., and weak relationships (p < .10) were also found for Coloburiscoides munionga and Asmicridea edwardsii. Drift was not associated with pool length for any species, suggesting that hydraulic conditions within a pool limit drift dispersal and not the total distance between riffle habitat patches.
4. Overall, our results suggest drift dispersal seems unlikely to be a major mechanism of long distance dispersal, for at least some common insects. These findings indicate that drift may play a more limited role in stream insect dispersal than is commonly considered and that flying adults may therefore have much greater influence on connectivity among populations.

     

芍药的访花昆虫和传粉昆虫

20 0 0～ 2 0 0 2年对内蒙古赤峰市高格斯台罕乌拉自然保护区内野生芍药 (PaeonialactifloraPall.)和内蒙古农校芍药园内栽培品种芍药的访花昆虫进行调查 ,经整理鉴定有 2 9种 ,自然保护区内芍药的访花昆虫种类有 1 7种 ,芍药园内的访花昆虫有 1 7种。根据传粉行为和数量的比较确定了自然保护区内主要传粉昆虫为丽斑芫菁、黄胫宽花天牛、黑胫宽花天牛、短毛斑金龟、饥星花金龟、白星花金龟和大淡脉隧蜂 ;芍药园内的主要传粉昆虫为意大利蜜蜂、棕边管食蚜蝇、长尾管食蚜蝇、大淡脉隧蜂、灰带管食蚜蝇和小淡脉隧蜂。     

Upstream-downstream movements of aquatic invertebrates in a Rocky Mountain stream

Simultaneous collections of drift and organisms moving either upstream or downstream in association with the substrate were made using a specially designed sampler. Samples were taken in a diel series along a transect across the study riffle of a Colorado foothills stream on six dates over an annual cycle. In addition to longitudinal movements, taxonomic composition and diel periodicity were evaluated. The insect-dominated fauna showed a net downstream displacement. Only the caddisflies Helicopsyche borealis and Hesperophylax occidentalis exhibited net upstream movement, primarily a result of low drift frequencies. The taxonomic composition of moving invertebrates differed from that of the benthos. Drift resembled downstream moving substrate-associated invertebrates in composition, but differed from that of the upstream directed fauna. Taxa collectively exhibited four types of diel patterns: 1) similar downstream (drift and substrate-associated movements) patterns, which generally differed from the upstream pattern; 2) similar benthic (upstream and downstream) patterns, which differed from that of drift; 3) aperiodic patterns; and 4) independent patterns for each type of directional movement. Analysis of size classes based on head capsule width for the mayfly Baetis tricaudatus showed significantly smaller size in stationary individuals compared with moving individuals in the population and revealed that nymphs moving during the day were smaller than those moving at night.     

Low‐level effects of inert sediments on temperate stream invertebrates

1. The delivery, entrainment and deposition of inert fine sediments are among the most significant contributors to stream and river impairment worldwide. Associated ecological effects have been observed frequently, but specific experiments to identify sensitivity and avoidance behaviour in stream organisms are few, particularly in headwaters. 2. In a field‐experiment, we added fine sand at low levels (c. 4–5 kg m^?2) to 10 m reaches of two replicate headwater streams in the Usk catchment (Wales, U.K.) over two periods (autumn and summer). Upstream reaches were used as control in a classic before‐after‐control‐impact design. Invertebrate drift and benthic composition were measured for 2 days before and 1 day after sediment impact. 3. Sediment addition significantly increased overall drift density (by 45%) and propensity (by 200%), with effects largest on the night following addition rather than immediately (i.e. within 9 h). The mayflies Baetis rhodani, B. muticus and Ecdyonurus spp., simuliid and chironomid dipterans, and helodid beetles were the strongest contributors. 4. There were no marked effects on benthic composition, but density declined in treated reaches by 30–60%, particularly in B. rhodani, Ecdyonurus spp. and Leuctra hippopus + L. moselyi. 5. All effects were consistent between both seasons and streams. 6. These data show how even low‐level, short‐term, increases in fine sediment loading to upland, stony streams can reduce overall benthic density through increased drift. We suggest that the likely cause of the delayed drift response was a change in habitat quality which prompted avoidance behaviour. Longer‐term experiments are required to assess whether these effects reduce fitness or explain the losses of some types of organisms observed recently in sediment‐impaired reaches of this and other catchments.