The Use of Conspecific Chemical Cues for Cannibal Avoidance in California Newts (Taricha torosa)

Adult California newts, Taricha torosa (Caudata: Salamandridae), prey on both conspecific egg masses and larvae. We used both laboratory and field experiments to determine if newt larvae use conspecific chemical cues to avoid adult intraspecific predators. Larvae showed significant hiding responses when exposed to adult cues in both the field and the laboratory. Larvae did not exhibit significant hiding responses to chemical cues from invertebrate predators.     

Population and Species Divergence of Chemical Cues that Influence Male Recognition of Females in Desmognathine Salamanders

Growing evidence indicates that males may be more discriminating of mating partners than often has been assumed. In the North American Ocoee dusky salamander, Desmognathus ocoee (Plethodontidae: Desmognathinae), sexual incompatibility among conspecific populations is high in encounters staged in the laboratory, at least in part because males fail to recognize ‘other’ females as appropriate targets for courtship. I used Y-mazes to test the hypothesis that males of D. ocoee discriminate between substrate-borne chemical cues produced by ‘own’ (homotypic) and ‘other’ (heterotypic) females. Males of four populations discriminated in favor of substrates soiled by homotypic females over clean (control) substrates (expt 1), suggesting that females produce chemical cues of sociosexual significance to males. Furthermore, males from these populations discriminated in favor of substrates soiled by homotypic females vs. substrates soiled by heterotypic females (expt 2), both conspecific and heterospecific (D. carolinensis and D. orestes). Thus, differences among populations and species in female chemical cues appear to affect the chemotactic responses of males. I suggest that, together with differences in behavioral signals and responses exhibited during courtship, differences in female chemical cues likely contribute to sexual incompatibility among populations and taxa of desmognathine salamanders.     

Chemical Alarm Cues Are Conserved within the Coral Reef Fish Family Pomacentridae

Fishes are known to use chemical alarm cues from both conspecifics and heterospecifics to assess local predation risks and enhance predator detection. Yet it is unknown how recognition of heterospecific cues arises for coral reef fishes. Here, we test if naïve juvenile fish have an innate recognition of heterospecific alarm cues. We also examine if there is a relationship between the intensity of the antipredator response to these cues and the degree to which species are related to each other. Naïve juvenile anemone fish, Amphiprion percula, were tested to see if they displayed antipredator responses to chemical alarm cues from four closely related heterospecific species (family Pomacentridae), a distantly related sympatric species (Asterropteryx semipunctatus) and a saltwater (control). Juveniles displayed significant reductions in foraging rate when exposed to all four confamilial heterospecific species but they did not respond to the distantly related sympatric species or the saltwater control. There was also a strong relationship between the intensity of the antipredator response and the extent to which species were related, with responses weakening as species became more distantly related. These findings demonstrate that chemical alarm cues are conserved within the pomacentrid family, providing juveniles with an innate recognition of heterospecific alarm cues as predicted by the phylogenetic relatedness hypothesis.     

Social Context Influences the Antipredator Behaviour of Fathead Minnows to Chemical Alarm Cues

Prey fishes, like many organisms under fluctuating predation threat, rely on multiple sources of information to accurately gauge current risk. This includes the use of chemical cues such as alarm cues from damaged conspecifics or familiar heterospecifics, as well as the odour of known predators. While each fish is well equipped with its own array of sensory abilities, they should also be alert to the behaviours of nearby neighbours who may have information they lack. In the present study, we tested the ability of fathead minnows to use social cues in combination with the odour of damaged conspecifics and heterospecifics to mediate the assessment of predation risk. Specifically, we tested whether the presence of a shoal of conspecifics or familiar heterospecifics would significantly change a minnow's antipredator behaviour when exposed to the odour of a damage‐release cue from a conspecific or ecologically similar heterospecific. The results of our study showed a significant interaction between the damage‐release cues to which the minnows were exposed and the presence/absence of shoalmates. These findings have important implications for the design of future investigations of antipredator responses because most studies of group‐living prey have been conducted on solitary subjects.     

Fish Faeces as the Primary Source of Chemical Cues Inducing Fish Avoidance Diapause in Daphnia Magna

In a laboratory batch culture experiment, females of Daphnia magna were exposed to five different experimental media containing either:(1) water from an aquarium with fish, (2) extract of fish faeces, (3) mixture of both media, (4) extract of homogenised conspecific Daphnia, or (5) control water without the addition of extra cues. The experiment was planned to test potential pathways of excretion of the chemical cues that induce resting-egg formation in D. magna and to find an effective way of collecting these chemical cues. The results indicate that fish faeces are the prevailing source of the chemical cues that induce resting-egg production in D. magna. The ease of collection and the possibility of storing it in a frozen state make it a convenient cue for inducing diapause response in Daphnia. The results of the experiment imply that in natural conditions Daphnia may face high concentration of the inductive signals once migrating to the bottom zone where fish faeces commonly accumulate.     

The Behavioural Response of Mayfly Nymphs (Stenonema sp.) to Chemical Cues from Crayfish (Orconectes rusticus)

Artificial reef systems play an important role in the increase of natural production of biological marine resources and they have been deployed worldwide. In Portugal, seven artificial systems have been deployed along the southern coast of the Algarve. Research to date has focussed mainly on fish populations, particularly those of economical importance. The present work aims to study the macrobenthic communities of the artificial reef structures, as these will enhance the food resources and shelter, making the reefs more attractive to fish. In particular, we experimentally analysed the sequence of colonisation of macrobenthic communities of the Ancão artificial reef system, which was deployed in the summer of 2002. The study of the colonisation of benthic communities was done using samples of concrete cubic units (15 × 15 cm) that were suspended at the reef modules at a depth of 20 m, at the time of the reef immersion. Four replicate samples were collected by SCUBA diving from two groups of the Ancão reef every three months from the starting date. Sampling was done using essentially non-destructive methods to assess the percentage cover of macrobenthic organisms in both vertical and horizontal surfaces. The percentage cover of the taxonomic groups was compared within the different surfaces of the samples and between the two reef groups. The bottom surface of cubic samples had a significantly higher colonisation related to the dominance of barnacle cover, probably due to lower sedimentation levels. Samples from both reef groups showed a similar pattern of colonisation. Barnacles, bryozoans and serpulids dominated the samples three months immediately after the beginning of the experiment. Other invertebrates groups, such as Porifera, Hydrozoa, Anthozoa, other sessile Polychaeta, Decapoda, Gastropoda and Bivalvia, were more abundant after six months of colonisation.     

Fathead Minnows, Pimephales promelas, Learn to Recognize Chemical Alarm Cues of Introduced Brook Stickleback, Culaea inconstans

In four experiments conducted over a 6-year period, we investigated whether fathead minnows, Pimephales promelas, could acquire the ability to recognize chemical alarm cues of introduced brook stickleback, Culaea inconstans. A laboratory experiment documented that stickleback-naïve minnows did not exhibit an anti-predator response when exposed to the chemical alarm cues of stickleback. In a laboratory experiment conducted 5 years after the introduction of stickleback to the pond, minnows exhibited an antipredator response to stickleback cues. Moreover, in a field experiment the minnows exhibited avoidance of areas labelled with stickleback alarm cues. Minnows raised from eggs taken from the test pond did not exhibit an anti-predator response to stickleback cues while minnows from the test pond that had experience with stickleback cues did respond to stickleback cues. Our results provide clear evidence that cross-species responses to chemical alarm cues of fishes can be learned. Learned recognition of alarm cues has important implications for predator/prey interactions.     

The nucleolar organizer of Plethodon cinereus cinereus (Green)

The lampbrush nucleolar organizers in P. c. cinereus are on the shorter arms of the 7th longest bivalent, near to the centromeres. The organizer consists of a non-chromomeric, Feulgen-negative section of the half bivalent axis inserted between typically chromomeric regions with normal lampbrush loops. The main axis of the organizer may appear double or single. The distributions and lengths of the double regions are variable. The axial strand of the organizer can be broken with DNase. Nucleolus-like objects are attached at irregular intervals along the organizer axis. The attached nucleoli closely resemble the free nucleoli in the same nucleus. Where free and attached nucleoli appear as beaded rings, the general characteristics and range of lengths of the attached rings are similar to those of the free rings. The attached rings occur singly, in pairs, or in clusters. The point of attachment of a ring is sometimes marked by a granule on the organizer axis. Pairs of attached nucleolar rings sometimes form double bridges in which the nucleoli extend linearly across a gap in the organizer axis. The length of the organizer varies from 20 μm to 300 μm, depending, at least in part, on the stage of oocyte development. The difference is a function of the length of the axial strand. Nucleolar organizers similar to that described for P. c. cinereus have been seen on the lampbrush bivalents of 7 other species of Plethodon and 2 species of Eurycea. In all of these, the 2 organizers of the nucleolus bivalents differ in length.     

Systematic Relationships of Hynobius okiensis among Japanese Salamanders (Amphibia: Caudata)

We conducted an electrophoretic survey to examine systematic relationships of a lotic-breeding salamander Hynobius okiensis endemic to Dogo Island of the Oki Islands, Japan, with several lentic and lotic-breeding Japanese species. Genetically H. okiensis with 2n=56 chromosomes was closer to the lentic-breeding H. nebulosus group (H. nebulosus and H. dunni) with the same chromosome number than to the lotic-breeding H. naevius group (H. naevius and H. kimurae) and H. boulengeri with 58 chromosomes. Chromosome number reduction from 58 to 56, possibly accompanied with a change in breeding environment from streams to still waters, is estimated to have first occurred in the nebulosus group of Hynobius. A reversal only in breeding habits then seems to have followed in steep, montane environments of the small island of Dogo, resulting in the speciation of H. okiensis.     

Context-dependent movement behavior of woodland salamanders (Plethodon) in two habitat types

Animal movement is critical to the maintenance of functional connectivity at the landscape scale and can play a key role in population persistence and metapopulation dynamics. The permeability of habitat to animal movement may vary as a result of either differential mortality, physical resistance, or simply the behavioral responses of organisms to perceived habitat quality. Understanding how and when animal movement behavior varies among habitat types is critical for identifying barriers to dispersal and predicting species distributions in relation to landscape features. We conducted an experimental translocation study and compared the movement success and behavioral strategies of plethodontid salamanders in both forest and open-canopy habitat. We found that individuals in closed-canopy forest oriented more strongly towards their home ranges and moved significantly farther on their release night. In spite of the clear differences in movement paths, the ultimate movement success of homing salamanders did not appear to vary with habitat type. Our study contributes to a growing body of literature suggesting the importance of recognizing the context dependence of animal movement behavior. Because the movement rates of displaced salamanders were significantly reduced in open-canopy, dispersal rates of plethodontid salamanders in open-canopy habitat are likely lower than in control forest. Further mechanistic studies focusing on habitat-specific movement behavior and survival costs will be valuable for effectively identifying and mitigating barriers to animal movement.     

山西天镇辛窑子早更新世犀科化石新材料（英文）

20世纪80年代在桑干河盆地一带考察泥河湾层时,在山西省天镇县南高崖乡的辛窑子沟一带发现了很多哺乳动物化石地点并出土了大量哺乳动物化石。最近对其中犀科化石的研究表明在辛窑子沟一带的早更新世地层中产出的犀类化石至少有两个种,裴氏板齿犀(Elasmotheriumpeii)和泥河湾披毛犀(Coelodontanihowanensis),可能还存在过第三个种。由于标本保存状况不理想,暂时鉴定为梅氏犀相似种(Stephanorhinus cf. S. kirchbergensis)。虽然后者的形态大小与梅氏犀最接近,但和泥河湾披毛犀也有相似之处,因此也有可能是这两个种之一的种内变异类型。同样,产于下沙沟地点被德日进和皮维托鉴定为有疑问的中国犀(Rhinoceros sinensis (?))也可能是梅氏犀或泥河湾披毛犀的种内变异类型。迄今为止在广义泥河湾盆地发现的早更新世犀类有两个确定的种和两个不确定的种。出土裴氏板齿犀的地点为下沙沟、山神庙咀、大黑沟及辛窑子沟;出土泥河湾披毛犀的地点为下沙沟、大南沟、东谷坨、山神庙咀及辛窑子沟。有疑问的中国犀仅出现在下沙沟,梅氏犀相似种仅出现在辛窑子沟。     

Chemical Alarm Signals Enhance Survival of Brook Charr (Salvelinus fontinalis) During Encounters with Predatory Chain Pickerel (Esox niger)

A diversity of aquatic organisms release chemical alarm signals when attacked or captured by a predator. These alarm signals are thought to warn other conspecifics of danger and, consequently, may benefit receivers by increasing their survival. Here we experimentally investigated the differences in behaviour and survival of hatchery-reared juvenile brook charr Salvelinus fontinalis that had been exposed to either brook charr skin extract (experimental treatment) or a control of swordtail skin extract (control treatment). Charr exposed to conspecific skin extract exhibited a significant reduction in movement and/or altered their foraging behaviour in the laboratory when compared with charr exposed to swordtail skin extract. We also exposed charr to either water conditioned by a single brook charr disturbed by a predatory bird model or water conditioned by a single undisturbed brook charr. Charr exposed to disturbance signals reduced activity significantly more than charr exposed to chemical stimuli from undisturbed charr. These results demonstrate the existence of both damage-released alarm signals and disturbance signals in brook charr. Wild brook charr also responded to damage-released alarm cues under natural conditions. Charr avoided areas of a stream with minnow traps labelled with conspecific alarm cues vs. control cues. During staged encounters with chain pickerel Esox niger in the laboratory, predator-naive charr fry were better able to evade the predator if they were previously warned by an alarm signal, thus suggesting a survival benefit to receivers. Collectively, these results demonstrate that the presence of alarm signals in brook charr has important implications for understanding predator–prey interactions.     

Preference for Chemical Cues Associated with Recent Prey in the Wolf Spider Hogna helluo (Araneae: Lycosidae)

In the wolf spider, Hogna helluo , we tested the response to insect and spider prey chemical cues and whether they show a preference for cues associated with prey consumed most recently. Thirty adult female H. helluo were maintained on a diet of either females of a smaller co-occurring wolf spider ( Pardosa milvina ) or domestic crickets ( Acheta domesticus ). A single P. milvina or cricket nymph was maintained on filter paper for 24 h, after which the papers from both prey sources were simultaneously presented to individual H. helluo from each diet treatment group. H. helluo locomotor behavior on each treatment and initial substrate preference was recorded (n = 15/treatment). H. helluo fed crickets showed significantly longer residence time and decreased mobility on filter paper previously occupied by a cricket; spiders fed P. milvina showed longer residence times and decreased mobility on filter paper previously occupied by P. milvina . H. helluo fed P. milvina exhibited an initial preference for substrates previously occupied by P. milvina but H. helluo fed crickets did not show a corresponding initial preference for crickets. Results suggest that H. helluo can detect distant cues associated with P. milvina but not crickets before contacting the substrate and that H. helluo respond to chemical cues from prey and show a preference for those cues associated with their most recent prey.     

Survival Benefit to Antipredator Behavior in the Amphipod Gammarus minus (Crustacea: Amphipoda) in Response to Injury-released Chemical Cues from Conspecifics and Heterospecifics

A wide range of aquatic taxa use environmental chemical cues for the assessment of predation risk. We examined whether Gammarus minus (Crustacea: Amphipoda) exhibit antipredator behavior in response to injury-released chemicals from conspecifics or heterospecifics (Crustacea: Isopoda). We then examined whether behavioral responses to these cues conferred survival benefits to the amphipods. In the first part of this study, we tested the behavioral response of G. minus to the following treatments: 1. water containing injury-released cues of conspecifics; 2. water containing injury-released cues of a sympatric isopod crustacean, Lirceus fontinalis; or 3. water containing no cues (control). Relative to the control, Gammarus responded to the conspecific cue by moving to the substratum and decreasing activity. In contrast, Gammarus responded to the heterospecific cue by moving up into the water column and increasing activity. In the second part of this study, we tested if the behavioral response to these cues confers a survival benefit to Gammarus when exposed to a predator. A green sunfish ( Lepomis cyanellus ) was retained behind a partition in the test tanks. Two minutes after the introduction of the chemical cues in the first test, the barrier was lifted and predation events recorded. Relative to the control, the time to the first attack increased for Gammarus exposed to conspecific cues and decreased for those exposed to heterospecific cues. These data indicate that Gammarus distinguish between chemical cues from conspecific and heterospecific crustaceans, and that the antipredator response to conspecific cues confers a fitness benefit (i.e. increased survival due to increased time to the first attack).     

Ultrastructure of the bone marrow of the salamander Plethodon glutinosus (Caudata: Plethodontidae)

The unusual lymphogranulopoietic bone marrow of the large lungless salamander Plethodon glutinosus was examined by light and electron microscopy. Developing neutrophils, eosinophils, and fat cells were found in large numbers, while lymphocytes of various sizes, plasma cells, plasmablasts, macrophages, pigment cells, and fibroblasts were present in more moderate numbers. Basophils were observed only rarely. Macrophages were found in extravascular locations and did not appear to be associated directly with the walls of the blood vessels supplying the marrow. Both neutrophils and eosinophils seemed to arise from small precursor cells whose ultrastructural features bore a resemblance in some ways to those of mammalian myeloblasts described by Bainton and Farquhar ('66). Developing neutrophils and eosinophils seemed to produce only single populations of specific cytoplasmic granules, rather than both primary (azurophilic) and secondary (specific) inclusions, as are produced typically by mammalian granulocytes. Both eosinophilic and neutrophilic granules were formed in association with Golgi complexes; and eosinophilic granules were much larger, more densely stained, and more regularly rounded in shape than the inclusions of developing neutrophils. Peroxidase activity was associated with the specific granules of neutrophils but seemed to be lacking in the granules of eosinophils. The specific granules of eosinophils were especially unusual because they contained irregularly shaped, lightly stained cores which occasionally displayed a distinctly crystalline substructural organization. The specific granules of basophils also possessed a prominent crystalline organization. The overall appearance of the marrow of Plethodon suggests that it functions not only as a valuable source of neutrophils, eosinophils, and cells of the lymphoid series, but also as a part of the phagocytic system of the animals and as an important repository for fat.     

金鱼藻的化学成分

从金鱼藻(Ceratophyllum demersum L.)全草的乙醇提取物中分离鉴定了其中7个,分别为:苜蓿素-7-O-β-D-葡萄糖苷(1) , naringenin-7-O-β-D-葡萄糖苷(2) ,七叶内酯(3) ,β-谷甾醇(4) , 7α-羟基-β-谷甾醇(5) , 7α-甲氧基-β-谷甾醇(6) ,十六碳脂肪酸(7)。化合物(3)为首次从金鱼藻中分离得到。