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1.
Arboreal animals negotiate a highly three-dimensional world that is discontinuous on many spatial scales. As the scale of substrate discontinuity increases, many arboreal animals rely on leaping or gliding locomotion between distant supports. In order to successfully move through their habitat, gliding animals must actively modulate both propulsive and aerodynamic forces. Here we examined the take-off and landing kinetics of a free-ranging gliding mammal, the Malayan colugo (Galeopterus variegatus) using a custom-designed three-dimensional accelerometry system. We found that colugos increase the propulsive impulse to affect longer glides. However, we also found that landing forces are negatively associated with glide distance. Landing forces decrease rapidly as glide distance increases from the shortest glides, then level off, suggesting that the ability to reorient the aerodynamic forces prior to landing is an important mechanism to reduce velocity and thus landing forces. This ability to substantially alter the aerodynamic forces acting on the patagial wing in order to reorient the body is a key to the transition between leaping and gliding and allows gliding mammals to travel long distances between trees with reduced risk of injury. Longer glides may increase the access to distributed resources and reduce the exposure to predators in the canopy or on the forest floor.  相似文献   

2.
Dermopterans are taxonomically-unique mammals, but little is known about their habitat requirements. The Sunda colugo (Galeopterus variegatus), which is one of only two living species of dermopterans confined to Southeast Asia, reportedly occurs in tropical forests, plantations, and gardens. Based on their ecology, however, we predict that tropical forests are likely to be their primary habitats. Here, we investigate environmental variables that account for the occurrence of G. variegatus in Singapore using Bayesian inference. Our results show that G. variegatus was only detected in transects with over 95% canopy cover, which was ultimately the most important predictor of colugo occurrence. Tropical forests, including disturbed forests, with relatively intact canopies are therefore vital for colugos to persist.  相似文献   

3.
Experimental infections with Yersinia pestis were followed in groups of rock squirrels. Development of coagulopathy and pneumonia were observed in 2-4% and 11-12% of the test animals, respectively. Susceptibility to experimental infection was heterogeneous with some animals surviving inoculation with large numbers of organisms and others succumbing after inoculation with small numbers. Production and longevity of serum antibody titers, as measured by passive hemagglutination tests, were variable as well, and apparently unrelated to dose. The data presented attest to the need for care in interpreting serologic tests results for individual animals.  相似文献   

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1. A low molecular weight, cadmium-binding protein has been isolated from Lumbriculus variegatus.2. The protein has an apparent molecular weight of 19 kD as estimated by Sephadex G-75 chromatography and is thought to be a dimer. It shows high absorbance at 254 nm and low absorbance at 280 nm.3. Amino acid analysis revealed a high content of cysteine (16.5%), and elevated amounts of aspartate (10.9%), serine (10.6%), glutamate (9.3%), glycine (11.7%), leucine (10%) and lysine (10%). The content of aromatic amino acids was low.4. After SDS-polyacrylamid gel electrophoresis three distinct bands with molecular weights of 19, 11.5 and 10.2 kDa, respectively, were found. The three bands are assumed to represent the dimer, the monomer and a partially carboxymethylated monomer.5. The protein is suggested to play an important role in the detoxification of cadmium.  相似文献   

6.
The euryhaline fish Cyprinodon variegatus variegatus (Cvv) is capable of tolerating ambient salinities ranging from 0.3 to 167 g l?1, but incapable of long‐term survival in freshwater (< 2 mM Na+). However, a population of this species, now designated as a subspecies (Cyprinodon variegatus hubbsi; Cvh), has been isolated in several freshwater (0.4–1 mM Na+) lakes in central Florida for the past ~150 ky. We previously demonstrated that Cvh has a significantly higher affinity for Na+ uptake suggesting that it has adapted to its dilute freshwater environment. We here evaluate whether Cvh should be considered a separate species by characterizing pre‐ and post‐zygotic isolation, Na+ transport characteristics of the two populations and their hybrids, and developing a molecular phylogeny of Cvv and Cvh populations in Florida using mtDNA sequence data. We found evidence of partial prezygotic isolation with Cvv females mating almost exclusively (89%) with con‐specific males in choice mating experiments. Partial post‐zygotic isolation was also observed with significant (59–89%) reductions in hatching success of hybrid embryos compared with con‐specific embryos. Na+ uptake kinetics in hybrids (both Cvv x Cvh and Cvh x Cvv) bred and raised under common garden conditions were intermediate to Cvh (high affinity) and Cvv (low affinity) indicating that observed differences are genetically based. Similar observations were made with respect to short‐term (96 h) survival of juveniles acutely transferred from 7 mM Na+ to a range of more dilute (0.1–2 mM Na+) freshwater. Finally, although phylogenetic analysis of Cvv and Cvh populations using mtDNA sequence for ND2 were unable to fully resolve a polytomy between Cvh and Cvv populations from northeastern Florida, these data do not falsify the hypothesis that Cvh is of monophyletic origin. Overall, the available data suggest that Cvh should be considered a separate species or at a minimum an evolutionarily significant unit.  相似文献   

7.
Between 1998 and 2008, 621 Steller sea lions (Eumetopias jubatus, SSL) were captured underwater by SCUBA divers and anesthetized with isoflurane (n = 602) or sevoflurane (n = 19). We found significantly faster induction time ( ± SD) for sevoflurane (11 ± 6 min) compared to isoflurane (14 ± 6 min), as well as an interaction between anesthetists using the isoflurane protocol. Severe hypothermia with temperatures <35°C were measured in 22% of all animals, and had significant associations with month, length of anesthesia, and sex. Mortality rate was low (0.33%). We conclude that both isoflurane and sevoflurane anesthesia were effective for field anesthesia to safely handle and sample SSL.  相似文献   

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The nesting biology, life history and pollen foraging of the minute Nomioides variegatus (Olivier) is described and illustrated. All Nomioides biological studies are reviewed. Nesting and foraging were observed over two years in a sandy natural area in the Rhône River delta region of southern France. Nest and cell structure was obtained from soil blocks removed from the nesting area and examined in the laboratory. Females, which were on average only 4.2 mm long, nested solitarily in loose aggregations in areas free of vegetation. Cells were placed from 6 to 12 cm deep, each terminating a lateral burrow off the main burrow. Cell walls were lined with a water proof wax-like lining. The pollen-nectar provision was a flattened sphere. The posterior end of the egg was embedded on the dorsal surface of the provision. Larval and pupal development was rapid, proceeding to adults by August, the over-wintering stage. Pollen foraging patterns were analyzed from both pollen provisions and fecal material for different nests (3) and cells (8). Nomioides variegatus is polylectic, but individuals bees exhibited a high degree of foraging consistency for the provisioning of single cells. Eleven different pollen types representing 10 plant families were found. In 1996, Ecballium elaterium (Cucurbitaceae) was the dominant pollen present in all samples but it was absent in 1997. Tamarix gallica (Tamaricaeae) was the dominant pollen type in 1997 and absent in 1996. A third pollen, Centaurium (Gentianaceae) was present in both years and represented 70% of some samples.  相似文献   

10.
Artificial agarose foods containing either starch, glycogen, carragheenan, alginate, casein, gelatin, albumin, or peptones at a concentration of 1% dry weight were not phagostimulatory. Artificial foods containing sugars, especially galactose, at a concentration of 0.005 M were phagostimulatory. Of the common amino acids, only L‐phenylalanine was phagostimulatory at this concentration. The initiation of feeding postures (movement of the spines, tube feet, peristome, and Aristotle's lantern) of Lytechinus variegatus was little affected by the concentration of plant extracts. Many aspects of this behavior were attributable to physical rather than chemical stimulation. Feeding rates of L. variegatus upon artificial agarose foods containing either Thalassia testudinum or Gracilaria verrucosa were directly dependent upon plant tissue concentration. All artificial agarose food‐items were initially moved to the mouth and fed upon, however the time spent feeding was directly dependent upon plant type and tissue concentration. Retention of the artificial food‐items upon the test after feeding was not influenced by plant type or tissue concentration. Differences in consumption of foods by L. variegatus are determined by the degree of persistence in feeding upon encountered items and not be selection before initiating feeding or by retention of food‐items for subsequent feedings.  相似文献   

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The sea urchin roe is among the highest valued seafood items in the world. Increasing demand has extended this fishery worldwide and cases of overfishing have been detected in some countries. On the eastern coast of Venezuela some species of sea urchin, such as Lytechinus variegatus, are consumed as food but studies to determine the abundance and size do no exist. Between February 1998 and April 1999 six sampling stations (depth under 5 m) in Cubagua island (perimeter 25 km) were visited in 11 occasions to study the population density of L. variegatus, with a 0.25 m2 quadrat thrown eight times over seagrass (Thalassia testudinum) beds. Temperature was determined on site, and water samples for salinity and dissolved oxygen concentration were collected. Each specimen was measured and returned to the sea. Diameter range was 8.6 to 74.2 mm (n=3 404) and mean size 26.56-55.34 mm. On the northern coast density varied from 2 to 23 urchins/m2; on the eastern coast from 15 to 82/m2 and from 21 to 58/m2 on the southern coast. On the north coast the seagrass beds are scarce.  相似文献   

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A new species of Kaempferia from Southern Laos, K. sawanensis, is described and illustrated. Relationship of this new species with other taxa is discussed.  相似文献   

15.
We describe and illustrate four new species, Peliosanthes choriandra, P. tatianae and Tupistra orlovii from central to northern Laos, and Rohdea filosa from northern Vietnam. These are all very local in distribution and endemic to the respective countries. We also report new localities and their ecological conditions for five other species of Peliosanthes (P. argenteostriata, P. hirsuta, P. irinae, P. micrantha and P. nivea) recently described from Laos and/or Vietnam. Furthermore, Peliosanthes nivea is recorded as new to the flora of Laos.  相似文献   

16.
A new species of Kaempferia from Southern Laos, K.sawanensis, is described and illustrated. Relationship of this new species with other taxa is discussed.  相似文献   

17.
A recent systematic survey program of protected areas in Laos documented douc langurs (Pygathrix nemaeus) widely between 14°25N and 18°38N. Their precise northern limit is unclear as security constraints prevented survey there, but the species is unlikely to occur in Laos north of 20°. All our records are of the nominate, red-shanked form, P. n. nemaeus, though in the far south, greatly reduced red on the legs suggests intergradation with another form. Our records are overwhelmingly from evergreen or semievergreen forest and from a wide altitudinal range (200–1600 m). In most sites habitat was little degraded, but whether this reflects choice for such habitats, or the generally lower hunting pressure within them, is unclear. The largest population occurs over 3000 km 2 of the Nam Theun basin and surroundings, encompassing the protected areas of Nakai-Nam Theun, Hin Namno and the proposed Nam Theun Extension. This is the most important population of red-shanked langurs in the world. Laos supports globally the vast majority of their conservable population. Douc langurs are threatened in Laos by habitat fragmentation increasing their vulnerability to the existing high hunting levels. They are a favored target for local consumption and for local and Vietnamese hunters and traders. Protective measures should center around implementing habitat conservation and antihunting measures in the recently-declared National Biodiversity Conservation Areas. A recent government initiative to reduce gun use in rural areas is likely to have a strong positive effect on the population. The best protection for some time will remain the inaccessibility of their habitat. Accordingly, road-building into remote forest and piecemeal clearance at its edges should thus be minimized. Cross-border attention should be given to wildlife trading, including measures to reduce market demand.  相似文献   

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Systematic Parasitology - Dermacentor laothaiensis n. sp. (Acari: Ixodidae) is described based on adults ex wild boar and vegetation from Laos and Thailand. Adults of D. laothaiensis n. sp. are...  相似文献   

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