Predation and competition within an assemblage of larval newts (Triturus)

The impact of crested newts (Triturus cristatus) on the smaller-bodied palmate and smooth newts (T helveticus and T vulgaris) was studied during the larval stages using a combination of field and laboratory experiments In pond enclosures T cristatus larvae had no effect on the two smaller species over the first four weeks of development By eight weeks, however. T cristatus had achieved a size advantage which enabled it to eliminate T helveticus and severely reduce T vulgaris by predation In laboratory trials under food-limited conditions, T helveticus and T vulgaris were slightly smaller when raised with T cristatus, suggesting that this predatory effect was complemented by interspecific competition during early development Predation of the smaller species started when T cristatus reached a threshold size of c 27 mm No reciprocal effects on T cristatus growth or survival were observed Although T cristatus may be a significant predator of congeneric species in natural ponds, other factors, such as differences in microhabitat selection, higher-order predator-prey interactions and the occasional desiccation of pond habitats may facilitate coexistence between the species     

The effect of pH on feeding behaviour in newt larvae (Triturus: Amphibia)

The feeding responses of three species of newt larvae were compared under circumneutral and sublethal acid conditions. Under acid conditions (pH 4.5) feeding behaviour was suppressed in palmate newts, Triturus helveticus, and smooth newts. T. vulgaris , but not in crested newts, T. cristatus. At low pH, approach and orientation towards food occurred in T. helveticus and T. vulgaris , but snapping was inhibited; T. cristatus snapped and consumed food immediately it was offered under the same conditions. These differences are not consistent with the apparent greater tolerance of T helveticus for acidified ponds. The observations suggest that the chemosensory system of T. helveticus and T. vulgaris may be impaired at low pH.     

转录因子ACZ影响冠突曲霉色素及产孢数量的研究

本实验室前期在高渗条件下筛选得到8个转录因子,其中ACZ (SI65-00458)基因表达量最高,推测ACZ基因在冠突曲霉中参与响应渗透压及调控孢子的产生。因而本研究利用同源重组原理,构建了ACZ基因敲除载体,通过农杆菌介导转化,筛选获得了ACZ敲除菌株,将敲除株分生孢子液接种在含不同浓度NaCl的MYA培养基上,以野生型冠突曲霉为对照,观察敲除株与野生型菌株的区别。研究发现:培养基中不加NaCl时色素有明显变化,野生型为黄色,敲除株为褐黄色;在低渗透压下,菌落边缘不规则;在高渗透压下,敲除株产生的分生孢子数量为野生型的4倍多;无论是在27℃还是在37℃培养,敲除株在低渗及高渗条件下,菌落直径都较野生型小,菌丝较稀疏。表明敲除ACZ基因会影响冠突曲霉菌丝生长、色素的合成及孢子的产生。     

Differential effects of pH and temperature on embryonic development in the British newts (Triturus)

Changes in the water quality and temperature relationships of ponds may affect the structure of amphibian assemblages. The survival, time to hatching, hatching size and hatching stage of newt embryos were studied in the three British species ( Triturus cristatus, T. helveticus and T. vulgaris ), at two temperatures and two pHs. All T. cristatus embryos failed to hatch at pH 4.5, whereas over 80% of T. helveticus and T. vulgaris embryos hatched successfully at the same pH. At pH 7.5, T. cristatus survival was the same as the other two species, after the 50% mortality due to the homomorphism of chromosome 1 was taken into account. Temperature had no effect on survival of embryos. Time to hatching was two to four times longer at 12°C than at 17°C. Low pH shortened development time in T. vulgaris but not in T. helveticus . Low pH, but not temperature, affected size at hatching, with T. helveticus and T. vulgaris embryos emerging at a smaller size and earlier stage of development under acidic conditions. This reduction of size at low pH affected T. vulgaris more than T. helveticus . We predict that T. cristatus embryos will be the most vulnerable of the three species to acidification in nature. Warm ponds will result in rapid embryonic development, but T. helveticus and T. vulgaris larvae hatching in acid ponds will do so at a smaller size and earlier stage of development. The pattern of vulnerability to acidification within amphibian assemblages may change during ontogeny.     

Fecundity of the newts Triturus cristatus, T. marmoratus and their natural hybrids in relation to species coexistence

The two larger newt species in Europe, Triturus cristatus and T. marmoratus , have largely exclusive distributions but live in sympatry in a small area in western France, where they also hybridize. Triturus cristatus is increasing in abundance in the area at the expense of T. marmoratus , although this study shows that T. marmoratus has higher relative lifetime reproductive success. Triturus marmoratus lays more eggs than its relative under controlled conditions, and more T. marmoratus eggs in relation to its relative abundance are found in natural breeding sites. The hybrids are even more fecund, but their eggs and embryos have a lower survival rate.
The data are compared for age at maturity and species longevity, and estimates of lifetime reproductive success show that T. marmoratus females are more fecund than T. cristatus females. There are no differences between the species in survival of the embryos. It is therefore not clear why T. cristatus is replacing T. marmoratus , but changes in terrestrial habitats due to human activity might be the explanation.     

Bichordites monastiriensis from the Pleistocene of southeast Jamaica

Bichordites monastiriensis Plaziat and Mahmoudi 1988, produced by burrowing spatangoid echinoids, is figured and described from shallow marine siliciclastic strata of the Pleistocene Old Pera Beds (Coastal Group) of southeast Jamaica. Its occurrence there represents only the second formal recording of this monospecific ichno‐taxon and extends its geographic range from the Mediterranean region to the Caribbean. The spatangoid species that produced this trace fossil is unknown, but, unlike examples from other areas, it is unlikely to be Echinocardium.     

Cyclaster danicus, a shallow burrowing non-marsupiate echinoid

The spatangoid Cyclaster danicus has been placed in the genus Brissopneustes by previous authors. The material from the Lower Danian of Denmark includes some abnormal individuals with depressed apical area. These have been previously interpreted as females with a marsupium. A study of both normal and abnormal tests indicates that the depressed apical area is not a marsupium but rather a malformation, possibly caused by adverse environmental conditions or by a parasite. The skeletal morphology indicates that C. danicus was a shallow burrowing form but the malformed individuals probably did not burrow.     

Scolicia shirahamensis isp. nov.: a triple-corded scolicia and its ichnological implications

Abstract

Peculiar meniscate burrows with three sediment cords occur in early to middle Miocene tidal-flat deposits of southwestern Japan. Two of the cords are situated at the bottom and the other is at its center. Detailed observations of the burrow structures and comparative neoichnological studies of modern spatangoid burrows in a tidal flat revealed that the former two were true drainage tubes and the latter was fecal in origin. The trace fossil was thus assigned to the ichnogenus Scolicia. Based on these findings, a new ichnospecies Scolicia shirahamensis isp. nov. has been described here. The central sediment cord is seemingly identical to the drainage tube of the ichnogenus Bichordites, another ichnogenus that has been commonly ascribed to a fossil spatangoid burrow, similar to Scolicia. Careless ichnogeneric identification of a spatangoid burrow, based only on the central sediment cord, therefore, may produce an incorrect identification.     

A morphometric study of a hybrid newt population (Triturus cristatus) T. carnifex): Beam Brook Nurseries, Surrey, U.K.

The crested or great crested newt ( Triturus cristatus spp) is declining and now considered threatened in many of the countries where it is present. This has resulted in the four members of the superspecies being afforded protection under local, national and international law. This study looks at a possible threat to T. cristatus in southern England through hybridization, by the introduction of a related alien species ( T. carnifex ). The study used multivariate morphometries to discriminate closely related species, and their hybrids. The character set involved both continuous and meristic data, collected through body measurements and colour pattern. The identification of the species and/or hybrids at the introduction site and surrounding areas was mapped. From the results it can be inferred that hybridization has taken place at the introduction site, but there is no morphological evidence for the spread of hybrids/aliens in to the surrounding areas.     

Microhabitat selection and feeding relations of smooth and warty newts, Triturus vulgaris and T. cristatus, at an upland pond in mid-Wales

The utilization of microhabitat and food resources by Triturus vulgaris and T. cristatus was studied in an upland pond in mid-Wales. From April to June T. vulgaris was more evenly distributed across the pond than T. cristatus , which showed a preference for the middle of the pond and the bottom of the water column. From July to September however, when most T. vulgaris had left the pond, T cristatus was evenly distributed within the water column and a much higher proportion was captured around the shorelines. Both species appear to be generalist predators with diets limited by prey size. Zooplankton were the most important prey for T. vulgaris , while leeches formed the bulk of the diet of T. cristatus . However, T. cristatus did not select larger-sized zooplankton than T. vulgaris . Large body size therefore enables T. cristatus to consume a wider range of prey sizes than T. vulgaris . Microhabitat niche overlap was greater than feeding niche overlap between the species.     

冠突曲霉Fig基因敲除菌株的构建及表型分析

为了研究冠突曲霉(Aspergillus cristatus) Fig基因的功能,本研究采用同源重组的方法获得敲除株。并对敲除株进行功能验证。结果显示对Fig基因敲除株培养观察并与野生型菌株相比发现,在含有不同浓度NaCl的MYA培养基中,仍能产生成熟的子囊孢子和分生孢子,但分生孢子数量是野生型的1/4,子囊孢子数量是野生型的1/5,且敲除株菌落几乎没有渗出液,无皱褶,菌落表面干燥,色素产生量急剧下降,这些结果表明Fig基因对冠突曲霉产孢起正调控,本实验为冠突曲霉发育调控机制的研究提供了一定的技术基础。     

Consequences of metamorphosis for the locomotor performance and thermal physiology of the newt Triturus cristatus

During metamorphosis, most amphibians undergo rapid shifts in their morphology that allow them to move from an aquatic to a more terrestrial existence. Two important challenges associated with this shift in habitat are the necessity to switch from an aquatic to terrestrial mode of locomotion and changes in the thermal environment. In this study, I investigated the consequences of metamorphosis to the burst swimming and running performance of the European newt Triturus cristatus to determine the nature and magnitude of any locomotor trade-offs that occur across life-history stages. In addition, I investigated whether there were any shifts in the thermal dependence of performance between life-history stages of T. cristatus to compensate for changes in their thermal environment during metamorphosis. A trade-off between swimming and running performance was detected across life-history stages, with metamorphosis resulting in a simultaneous decrease in swimming and increase in running performance. Although the terrestrial habitat of postmetamorphic stages of the newt T. cristatus experienced greater daily fluctuations in temperature than the aquatic habitat of the larval stage, no differences in thermal sensitivity of locomotor performance were detected between the larval aquatic and postmetamorphic stages. The absence of variation across life-history stages of T. cristatus may indicate that thermal sensitivity may be a conservative trait across ontogenetic stages in amphibians, but further studies are required to investigate this assertion.     

Trapping, care, and laboratory management of the silvered leaf monkey (Presbytis cristatus)

The silvered leaf monkey (Presbytis cristatus) from South Kalimantan ( Borneo ), Indonesia is a natural host for a variety of filarial nematodes including Brugia malayi and Wuchereria kalimantani . Experimental studies show that it is host for W. bancrofti, a filarial nematode causing elephantiasis in man. Presbytis cristatus is a gregarious primate of primary and secondary forests, roaming in troops of 20-30 members. Primarily a fruit and leaf eater under natural conditions, this monkey can adapt to a laboratory diet of commercial monkey chow supplemented with fruits and vegetables. Troops, led by an alpha male, immediately respond to protect their young during stressful or dangerous situations. Infants are born singly and are bright orange. Transition to the adult grey and black coloration begins three to five months after birth. Silvered leaf monkeys can be readily trapped. Initially they are aggressive and will attack but become tractable several days after capture. Reaching upward is an important feeding behavior of the silvered leaf monkey and they will not feed from the floor of the cage. In the laboratory they are nonaggressive and lend themselves to various procedures such as blood drawing and examination. Silvered leaf monkeys travel well in commercial animal transport cages. In the United Stages they are not an endangered species and can be readily imported. In Indonesia they are not protected by law and can be exported.     

Parasite–grass–forb interactions and rock–paper– scissor dynamics: predicting the effects of the parasitic plant Rhinanthus minor on host plant communities

1.  Parasitic plants affect the growth, reproduction and metabolism of their hosts and may also influence the outcome of competitive interactions between host species and, consequently, the structure of entire host communities.
2.  We investigate the effect of the root hemiparasitic plant Rhinanthus minor on plant community dynamics using a spatial theoretical model. The model is parameterized with data from pairwise interaction experiments under two nutrient levels between the hemiparasite and three grass species ( Cynosurus cristatus , Festuca rubra and Phleum bertolonii ) and three forb species ( Leucanthemum vulgare , Plantago lanceolata and Ranunculus acris ).
3.  Relative interaction coefficients were intransitive, with the dynamics of the system conforming to a rock–paper–scissors game. Stable deterministic dynamics emerge from parameters obtained under low-nutrient conditions. Under high-nutrient conditions, the dynamics are unstable, but are stabilized in spatially explicit models. The outcomes are sensitive to initial spatial pattern and frequency.
4.   Synthesis . This study supports the idea that hemiparasite populations may form 'shifting clouds' in natural populations and explains seemingly unpredictable shifts in host community structure following introduction of hemiparasites. Management of plant communities using hemiparasites needs to take these complex dynamics into account.     

基于线粒体基因分析蓝孔雀与绿孔雀的遗传差异

种间的遗传差异是物种分类和确定保护管理单元的基础,本研究利用DNA条形码技术对未知样本进行鉴定,通过NCBI进行BLAST得到结果是:与绿孔雀的同源性为96%。近一步通过对蓝孔雀(Pavo cristatus)和绿孔雀(Pavo muticus)线粒体细胞色素C氧化酶Ⅰ(cytochrome coxidaseⅠ,COⅠ)基因及线粒体基因组的比较分析,结果表明两物种间的COⅠ基因在碱基组成、核苷酸多样性等各项指标上均具有明显差异。遗传距离分析结果表明蓝孔雀与绿孔雀种内遗传距离为分别0和0.012,种间遗传距离为0.045,表明种间仍具有明显的遗传差异。通过对两物种线粒体基因组各基因的比较分析,发现ND1基因变异位点所占比例相对较高,考虑作为绿孔雀和蓝孔雀种群遗传学研究的最优分子标记。本研究将为分析孔雀类群间的系统发育及制定绿孔雀的保护措施提供了更多科学依据。     

Observations on the morphology of Echinocardium cordatum (Echinoidea: Spatangoida) from diverse geographical areas

Various test features in six specimens of Echinocardium cordatum collected from South Africa, Trindade Island (South Atlantic), Australia, Japan and Ireland were compared with previously established data relating to British and New Zealand specimens. Morphological variations between the specimens were interpreted as infra-specific differences and no evidence was detected that the spatangoid conventionally defined as E. cordatum is more than a single species throughout its extensive geographical range.     

Characterization and comparative immunoreactivity of antibody to newt (T. cristatus) globins

Rabbit antisera to newt (T. cristatus) globin were produced by repeated injections of globin and antiglobin antibodies purified by chromatography on globin-Sepharose 4B. Ouchterlony and SDS PAGE analysis indicated that the material eluted from the affinity column was rabbit IgG. The antiglobin antibodies tested by immunodiffusion and ELISA cross-reacted with native hemoglobin and globin from T. cristatus and to varying extents with globins of N. viridescens, R. pipiens and X. laevis, but not with human globin. The degree of cross-reactivity appeared to parallel the evolutionary relatedness of these species, suggesting common antigenic determinants among globins of various vertebrate species.     

The origin of echinoid shell beds in siliciclastic shelf environments: three examples from the Miocene of Sardinia,Italy

Three mass accumulations of sea urchins from the Miocene of Sardinia show a number of taphonomic features which set them apart from previously described echinoid assemblages from the Cenozoic in which they represent: (1) monotypic assemblages; (2) include very well‐preserved remains of either regular or spatangoid echinoids; and (3) originate in deeper water environments. These accumulations are compared using a detailed sedimentological and taphonomic analysis including preservational fabrics, taphonomic signatures, size frequency distributions, density of occurrences and preferred orientations. The possible role of gregarious behaviour contributing to mass occurrences and the specific sedimentary events leading to the excellent preservation are discussed. The interpreted depositional environment of all three deposits is that of a storm‐dominated, siliciclastic shelf environment. A phymosomatid assemblage represents rapid burial through obrution of a highly dense, freshly dead community. A Brissopsis‐dominated spatangoid assemblage represents a mixed accumulation of parautochthonous and transported skeletons. The third assemblage consisting of regular echinoid spines and rare tests represents a composite tempestite. Differences in the depositional environments are related to their position along onshore–offshore gradient with the first two beds originated in a deeper setting than that of the spine accumulation. This study shows that the preservation of assemblages containing complete regular echinoids and spatangoids is higher in deeper water settings than in shallow water environments.