Feeding strategy of two sympatric anostracan species (Crustacea)

The transport rate of chalk, clay particles and algal cells (Scenedesmus sp.) through the digestive tract of Streptocephalus torvicornis and Branchipus schaefferi is described under experimental conditions. Differences in transport rate as well as in the degree of digestion at a fixed particle density of algae were found. In S. torvicornis, the transport rate is higher and the digestion of algae lower than in B. schaefferi. These differences might reflect trophic differences related to niche partitioning in these sympatric species. This revised version was published online in August 2006 with corrections to the Cover Date.     

Some notes on the ecology of a GermanBranchipus schaefferi population (Crustacea: Anostraca)

Habitat preference, seasonal occurrence, starvation resistance, hatching eggs ofBranchipus schaefferi, and effects of predation onB. schaefferi were studied.Branchipus was only present in turbid, unvegetated ponds and absent in ponds which contain higher aquatic vegetation and theSpirogyra sp. The first individuals ofB. schaefferi appeared in April when water temperature was 10 °C and the last adults in November at a water temperature of 3.5 °C. Up to 6 reproducing generations were observed during this period. Abundance ofB. schaefferi was higher in temporary ponds than in permanent ponds. Sex ratio was close to unity for most of the year. Body size ofB. schaefferi males and females was significantly positively correlated with pond volume. Without foodB. schaefferi could survive for 1.5 to 2 days at 20 °C and 4 to 5 days at 10 °C. Hatching success of eggs decreased when eggs were dried for 7 months. Freezing of eggs had no effect on hatching success. From] the predators tested,Chaoborus sp. larvae clearly selected smallB. schaefferi; one consumed approximately 6Branchipus d–1 at a density of 6 to 12 prey 1–1. The other predators, dragonfly larvae, and larvae and adults ofTriturus alpestris selected alternative prey types, for exampleTubifex sp. and ostracods.     

中国蛇根草属(茜草科)几种植物的分类学订正

根据对中国蛇根草属Ophiorrhiza植物标本的研究和野外调查,将琼崖蛇根草O.aureolina f.qiongyaensis Lo和溪畔蛇根草O.humilis Tseng归并入短小蛇根草O.pumila Champ.ex Benth.,将海南蛇根草O.hainanensis Tseng归并入垂花蛇根草O.nutans C.B.Clarke,将广西蛇根草O.kwangsiensis Merr.exLi和变黑蛇根草O.nigricans Lo归并入日本蛇根草O.japonica Bl.,将龙州蛇根草O.longzhouensis Lo和圆锥蛇根草O.paniculiformis Lo归并入广州蛇根草O.cantoniensis Hance。     

国产赖草属(禾本科)两个类群的修订

根据标本研究、野外考察和实验观察,对国产赖草属Leymus两个类群进行了分类修订,将阿尔金山赖草Leymus arjinshanicus D．F．Cui和L．aerginshanicus D．F．Cui ssp．ruoqiangensis（S．L．Lu＆Y.H．Wu）D．F.Cui处理为若羌赖草L．ruoqiangensis S．L．Lu＆YH．Wu的新异名,将纤细赖草L．secalinus（Georgi）Tzvel．var．tenuis L．B．Cai提升为一个独立的种L．tenuis（L．B．Cai）L．B．Cai．     

Causes of a non-random pairing by size in the brine shrimp,Artemia salina: (Crustacea: Anostraca)

Summary Brine shrimp (Artemia salina) males and females entered precopula assortatively by size in the laboratory; large males also had a pairing advantage over smaller males. We investigated the causes of such nonrandom pairing to test hypotheses on size-assortative mating.We found precopulatory biases with respect to male size in the absence of direct competition among males (which produces pairing biases in other species). Large males encountered females significantly more often than did small males. Similarly, large females encountered males more often than did small females, but showed less willingness than small females to enter precopula when housed with small males. Consequently, large females took longer than small females to enter precopula with small males. Although large males entered precopula readily with small females, such size-mismatched pairs appeared short-lived.We conclude that non-random pairing by size in A. salina is determined by several factors including: encounter rates between males and females of different sizes, female behavior, and time following initial pair formation. Our results are likely applicable to other species and can help explain variation for selection on size or other traits.     

Taxonomic notes on the paper wasps of the genus Ropalidia in the Indian subcontinent (Hymenoptera: Vespidae)

The taxonomy of Ropalidia wasps in the Indian subcontinent is revised, recognizing 26 species in the subcontinent. Their diagnostic characteristics are summarized in a key to species. New synonymies proposed in the present study are: R. bicolorata shiva Das and Gupta, 1989 under R. bicolorata van der Vecht, 1962; R. colorata sordida van der Vecht, 1941 under R. colorata van der Vecht, 1941; R. rodialipa Lambert and Narendran, 2005 and R. anupama Lambert and Narendran, 2005, both under R. cyathiformis Fabricius, 1804; R. jacobsoni flavoscutellata Das and Gupta, 1989, and R. bangalorica Lambert and Narendran, 2005, both under R. jacobsoni du Buysson, 1908; R. travancorica Lambert and Narendran, 2005, under R. marginata Lepeletier, 1836; R. sridharani Lambert and Narendran, 2005, under R. rufocollaris Cameron, 1900; Ropalidia rufoplagiata nursei van der Vecht, 1941 under R. rufoplagiata Cameron, 1905; Icaria lugubris Smith, 1858, under R. sumatrae Weber, 1801; and a revised synonymy is Icaria pendula Smith, 1857, under R. variegata Smith, 1852. The new replacement name Ropalidia kasaragodensis Lambert and Narendran is proposed for R. indica Lambert and Narendran, 2005, non van der Vecht, 1941.     

Distribution,diversity and conservation of Anostraca (Crustacea: Branchiopoda) in southern Africa

Southern Africa is defined here as Africa south of the Zambezi and Kunene Rivers. Here, annual average rainfall, rainfall season, and effective temperature are climatic factors which influence anostracan distribution. The type of temporary pool also appears to have some effect on distribution. Areas of high species richness are not confined to any particular climatic region and such areas occur in arid, montane and subtropical regions of southern Africa. Forty-six anostracan species have been recorded from the subcontinent and 80% of these are endemic. IUCN Red Data assessment of species revealed that two species can be considered 'Critically Endangered', while a further four are 'Endangered', and three are 'Vulnerable'. Many parts of southern Africa have been inadequately sampled but in South Africa, where the anostracans are relatively well known, temporary pool inhabitants are threatened mainly by agriculture, urbanization, pollution and pesticides. This revised version was published online in August 2006 with corrections to the Cover Date.     

Evidence for sex-related differences in phototactic bahaviour ofStreptocephalus proboscideus (Crustacea: Anostraca)

The phototactic behaviour of adults of the Sudanese fairy shrimpStreptocephalus probiscideus was studied under laboratory conditions. Males were less negatively phototactic than females. This was also evident when colour filters were used. females only became little less negatively phototactic under yellow light, whereas males showed a strong positively phototactic response. The response to the positioning of a yellow filter was stronger than to the use of a red or blue filter for both sexes. The laboratory findings were compared with casual field observations onStreptocaphalus torvicornis that indicate differential vertical distribution between the sexes and a nocturnal vertical migration. Migratory behaviour with ascent starting at dusk is also predicted forS. proboscideus. This behaviour may reduce common stress factors in desert pools such as photodamage, visual predation pressure, and high surface temperatures.     

The filtration apparatus of Anostraca (Crustacea): species-specific setulation in the genus Streptocephalus

The structure of the setae, setules, spines and spinules on the limbs of males and females of Streptocephalus torvicornis, S. rubricaudatus and S. proboscideus are described, based on scanning electron micrographs. The data disclose significant variation among the three species in fine structure of the setules and inter-setular distance. The variation may be related to different trophic specialisations, facilitating the sympatric occurrence of congeneric species.     

Biogeography and ecology of Anostraca (Crustacea) in middle Paroo catchment of the Australian arid-zone

Fourteen species of Branchinella and one each of Parartemia, Streptocephalus (Parastreptocephalus) and an undescribed branchipodid genus occur in a limited area (2000 km²) of the Paroo in northwestern New South Wales and southwestern Queensland. Syntopic coexistence was common (55% of collections) but to a large degree species interactions are minimized by habitat factors of turbidity, salinity and length of the wet phase in decreasing order of importance, and by a species factor of relative size. Discrete habitats such as claypans had a similar species composition each time they filled, but creek pools and other connected sites had variable species composition over time. The high biodiversity is explained by the presence of many distinct types of wetlands, each with their own characteristic anostracans.     

Regional structuring of genetic variation in short-lived rock pool populations of Branchipodopsis wolfi (Crustacea: Anostraca)

The genetic structure of three metapopulations of the southern African anostracan Branchipodopsis wolfi was compared by analysing allozyme variation at four loci (PGM, GPI, APK, AAT). In total, 17 local populations from three sites (metapopulations) were analysed from rock pools in south-eastern Botswana ranging from 0.2 to 21 m² in surface area. In three populations we found significant deviations from Hardy-Weinberg (H-W) equilibrium at one or more loci due to heterozygote deficiencies. Genetic variability at one site was significantly lower than at the other sites, which may be linked to a greater incidence of extinction and recolonisation, as the basins at this site are shallower and have shorter hydrocycles. Across all local populations, a significant level of population differentiation was revealed. More than 90% of this variation was explained by differentiation among sites (metapopulations), although this differentiation did not correlate with geographic distance, or with environmental variables. Genetic differentiation among populations within metapopulations was low, but significant at all sites. At only one of the sites was a significantly positive association measured between genetic and geographic distance among local populations. Our data suggest that persistent stochastic events and limited effective long-range dispersal appear to dominate genetic differentiation among populations of B. wolfi inhabiting desert rock pools. The lack of association between geographic distance and genetic or ecological differences between rock pool sites is indicative of historical stochastic events. Low heterozygosity, the significant deviations from H-W equilibrium, and the large inter- but low intra-site differentiation are suggestive of the importance of short-range dispersal. Gene flow between metapopulations of B. wolfi appears to be seriously constrained by distances of 2 km or even less. Received: 28 June 1999 / Accepted: 10 January 2000     

On predatory tendencies in the feeding ecology of the fairy shrimp Streptocephalus proboscideus (Frauenfeld, 1873) (Crustacea: Anostraca)

The feeding habits of the filter-feeding fairy shrimp Streptocephalus proboscideus are documented experimentally by offering them ciliates, Volvox, rotifers, nematodes and small crustaceans as prey. Escape capabilities (e.g. swimming speed) rather than size or shape were found to determine these animals' vulnerability to predation by the fairy shrimp. Ingestion rates for Volvox increased hyperbolically with size and, at the high temperatures in which they live, fairy shrimps may daily remove the equivalent of their body weight from the environment.     

A Possible Extra-Ovarian Site for Synthesis of Lipovitellin During Vitellogenesis in Artemia sp. (Crustacea; Anostraca)

Summary

Lipovitellin samples, extracted from yolk platelets of cysts, were applied to SDS-PAGE. A female specific antiserum was raised against the high molecular weight apoprotein lipovitellin alpha-1 (LV-α1) of the lipovitellin complex. This anti-LV-α1 was used in the peroxidase-anti-peroxidase staining method with frontal paraffin sections (of 4μm) of whole embedded Artemia. Females were studied during a complete vitellogenic cycle. The presence of exogenous yolk precursors in the fat storage cells of the thoracopods of female Artemia was demonstrated. The amount of the female specific yolk polypeptides and the number of positively stained cells changes during the vitellogenic cycle. In vitro experiments with ³⁵S-radiolabelled methionine show the synthesis of lipovitellin-like substances in the fat storage cells of vitellogenic females.     

The life history of Chirocephalus kerkyrensis Pesta (Crustacea: Anostraca) in temporary waters of Circeo National Park (Latium,Italy)

The life cycle of Chirocephalus kerkyrensis, a typicalspecies of the Mediterranean plain forest, was studied in thefield during 1990/91 and 1991/92.Temperature, and its variation, was the major factor affectinglife history. Marked, sudden temperature fluctuations resultedin depressed growth and longevity. Fertility was positivelycorrelated (P<0.001) with female body length. Nodecline in egg production was observed at the end of life, incontrast to other species. Hatching was observed after a longdrought followed by alternating wet and dry phases. Laboratorytests on hatching gave contrasting results and showed thatdrying is not obligatory. Cysts stored in 100% relativehumidity gave higher numbers of nauplii after a shorter timethan dried ones, at all temperatures tested.     

Uptake of lead,cadmium and zinc by the fairy shrimp,Branchinecta longiantenna (Crustacea: Anostraca)

Individuals of the fairy shrimp, Branchinecta longiantenna, were subjected to 5 concentrations (0.1 to 15 mg l^–1) of Pb in diluted habitat water at 13 °C. Lead concentrations (mg kg^–1 wet weight) in the animals were determined at 2-day intervals by digestion in nitric acid followed by atomic absorption analysis. The shrimp were also subjected to 0.1 mg l^–1 media of Cd and Zn, separately.Uptake rates by the fairy shrimp for the three metal ions at 0.1 mg l^–1 were: 0.111, 0.0885, and 0.0460 mg kg^–1 day^–1 for Zn, Pb, and Cd, respectively. After 2 days in 1.0 mg l^–1 Cd or Zn, the animals expired; but they surviced for 8 days in a 10 mg l^–1 Pb medium and for 2 days in 25 mg l^–1 Pb. Lead uptake demonstrated a linear dependence on the Pb concentration in the media.Shrimp survived at much higher tissue accumulations of Pb compared to Zn and Cd. Estimated lethal doses were 20, 1.2–2.4, and 0.4–1.4 mg kg^–1 wet weight for Pb, Zn, and Cd, respectively. Pb was found to be at much lower concentration than Cd or Zn in the natural pond water but between Cd and Zn levels in the sediment. Thus Cd and Zn probably present a greater threat to B. longiantenna than Pb, although Pb may be in higher concentration in the environment.Contribution 47, Laboratory of Ecology, The Claremont Colleges, Claremont, CA 91711, USA. Send reprint requests to Clyde Eriksen.     

On the occurrence of Streptocephalus torvicornis Waga 1842 (Crustacea,Anostraca) on a coastal island off Italy

The presence of Streptocephalus torvicornis on one coastal island off Italy (Cottarelli & Mura, 1995) is confirmed. Two years of sampling revealed an erratic pattern of occurrence, however, likely related to the unstable nature of the environmental characteristics. Such an unpredictability might be alternatively explained by a colonization-extinction process, or by adaptation to variations in annual weather (Donald, 1983). This revised version was published online in July 2006 with corrections to the Cover Date.     

番茄醇酰基转移酶基因SlAAT1克隆、序列分析和原核表达

酯类物质是许多果实香气的主要成分。醇酰基转移酶(AATs)是酯类化合物合成的关键酶。本研究通过反转录PCR,从番茄的成熟果实中克隆了SlAAT1基因(GenBank登录号为JQ070977),其编码一个含有442个氨基酸残基的蛋白,含有醇酰转移酶BAHD家族的H-x-x-x-D和DFGWG保守基序。系统进化分析表明,SlAAT1与苹果MpAAT1,山字草的BEBT及烟草Hsr201等聚在同一分支,进化关系较近。SDS-PAGE电泳分析表明,转化SlAAT1基因的大肠杆菌BL21(DE3)在22℃、0.8 mmol·L^-1 IPTG条件下可获得大量的可溶性目标蛋白。同时,纯化的SlAAT1大肠杆菌重组蛋白的体外酶活性分析表明了SlAAT1重组蛋白具有醇酰基转移酶活性,可能参与了酯类挥发性成分的合成。     

Sexual and developmental differences in the protein pattern of haemolymph and body tissues of Streptocephalus dichotomus Baird (Crustacea: Anostraca)

The protein pattern of haemolymph and body tissues of the freshwater fairy shrimp Streptocephalus dichotomus has been investigated in both sexes, using polyacrylamide disc gel electrophoresis. The electropherograms of four developmental stages show variations in number and intensities of protein fractions. In Stage III, two female-specific proteins of glycolipoprotein nature appear. This stage corresponds to maturity: females begin to possess mature oocytes in the ovary. These two vitellogenic proteins are well represented in the female haemolymph, ovary and freshly laid eggs, but are absent in the male haemolymph. A heterosynthetic mode of yolk formation is thus evident in this anostracan. The two sex-limited proteins are only faintly represented in shelled eggs, suggesting an early utilization of these compounds in embryogenesis.