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1.
Tigers are globally threatened and their conservation relies on intact habitat that supports key large prey. The Churia habitat is relatively unknown even though it occupies a significant portion of the forested landscape of the Terai Arc, which stretches over 1000 km in a narrow band across Nepal and India, parallel to the Himalayas. To address this lack of detailed information relevant to tiger conservation, we used sign surveys to estimate occupancy probability for 5 focal prey species of tigers (gaur, sambar, chital, wild pig, and barking deer), and assess tiger habitat use within 537 km2 of the understudied Churia habitat in Chitwan National Park (CNP), Nepal. Multi-season occupancy models allowed us to make seasonal (winter vs. summer) inferences regarding changes in occupancy or habitat use based on covariates influencing occupancy and detection. We found that sambar had the largest spatial distribution occupying 431–437 km2, while chital had the smallest at 100–158 km2 across both seasons. The gaur population showed the most seasonal variation occupying from 413 to 318 km2, suggesting their migration out of the Churia in summer and moving in during winter. Wild pigs showed the opposite trend occupying from 444 to 383 km2; suggesting moving into Churia in summer and out in winter. Barking deer were widespread in both seasons (329–349 km2). Tiger habitat use (\({{\hat{\varPsi } }}({\text{SE}})\)) was higher in winter 0.63 (0.11) than in summer 0.54 (0.21), but confidence intervals overlapped and area used was similar across seasons, 337 km2 (winter) to 291 km2 (summer). Available habitat, distribution of water sources, and human disturbance were the most common variables influencing spatial distribution of prey and habitat use of tigers at different spatial scales. Overall, we found high prey occupancy and tiger habitat use, suggesting the Churia is valuable habitat for ungulates and tigers. Given that this habitat accounts for 639 km2 within CNP and 7642 km2 across the entire Terai Arc, the Churia should no longer be neglected in global tiger conservation planning.  相似文献   

2.
Conserving large populations with unique adaptations is essential for minimizing extinction risks. Sundarban mangroves (>10,000 km2) are the only mangrove inhabited by tigers. Baseline information about this tiger population is lacking due to its man-eating reputation and logistic difficulties of sampling. Herein, we adapt photographic capture-mark-recapture (CMR) and distance sampling to estimate tiger and prey densities. We placed baited camera stations in a typical mangrove in 2010 and 2012. We used telemetry based tiger home-range radius (5.73 km, SE 0.72 km) to estimate effective trapping area (ETA). An effort of 407 and 1073 trap nights were exerted to photocapture 10 and 22 unique tigers in 2010 and 2012. We accounted for use of bait by modelling behaviour and heterogeneity effects in program MARK and secr package in program R. Using traditional CMR, tiger number was estimated at 11 (SE 2) and density at 4.07 (SE range 3.09–5.17) in 2010 while in 2012, tiger number was 24 (SE 3) and density 4.63 (SE range 3.92–5.40) tigers/100 km2. With likelihood based spatially explicit CMR, tiger densities were estimated at 4.08 (SE 1.51) in 2010 and 5.81 (SE 1.24) tigers/100 km2 in 2012. Using distance sampling along water channels, we estimated chital density at 5.24/km2, SE 1.23 which could potentially support 4.68 tigers/100 km2 [95 % CI (3.92, 5.57)]. Our estimates suggest that Sundarban tiger population is one of the largest in the world and therefore merits high conservation status.  相似文献   

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5.
Prey preferences of large carnivores (tiger (Panthera tigris), leopard (Panthera pardus) and dhole (Cuon alpinus)) in the tropical forest of Anamalai Tiger Reserve (ATR) were evaluated. This was the first study in ATR to estimate the density of prey and the food habits of these large carnivores. The 958-km2 intensive study area was found to have a high mammalian prey density (72.1 animals per square kilometre) with wild boar (20.61 animals per square kilometre) and chital (20.54 animals per square kilometre) being the most common species, followed by nilgiri tahr (13.6 animals per square kilometre). When the density figures were multiplied by the average weight of each prey species, a high biomass density of 14,204 kg km−2 was obtained for the intensive study area. Scat analysis and incidental kill observation were used to determine the dietary composition of these predators. During the study from the period of March 2001 to April 2004, 1,145 tiger scats, 595 leopard scats and 2,074 dhole scats were collected and analysed. Kill data were based on direct observation of 66 tiger kills and 39 leopard kills. Sambar, with a density of 6.54 kg km−2 was the preferred prey for these carnivores. Sambar constitutes 35% of the overall diet of tiger, whereas it constitutes 17% and 25% in leopard and dhole diets, respectively. Chital was utilized less than sambar in the range of about 7%, 11% and 15% by tiger, leopard and dhole, respectively. Predator diet was estimated more accurately by scat analysis, which reveals 30% of smaller prey species in leopard’s diet, which was not observed by kill data. This study reveals that ATR harbours high prey density, and these large carnivores seem mostly dependent on the wild prey rather than on domestic livestock as in some other areas in the subcontinent. These factors make ATR a potential area for long-term conservation of these endangered carnivores.  相似文献   

6.
As part of a national strategy for recovering tiger populations, the Myanmar Government recently proposed its first and the world’s largest tiger reserve in the Hukaung Valley, Kachin State. During November 2002–June 2004, camera-traps were used to record tigers, identify individuals, and, using capture–recapture approaches, estimate density in the reserve. Despite extensive (203 trap locations, 275–558 km2 sample plots) and intensive (>4,500 trap nights, 9 months of sampling) survey efforts, only 12 independent detections of six individual tigers were made across three study sites. Due to the sparse data, estimates of tiger abundance generated by Program CAPTURE could not be made for all survey sites. Other approaches to estimating density, based on numbers of tigers caught, or derived from borrowed estimates of detection probability, offer an alternative to capture–recapture analysis. Tiger densities fall in the range of 0.2–2.2 tigers/100 km2, with 7–71 tigers inside a 3,250 km2 area of prime tiger habitat, where efforts to protect tigers are currently focused. Tiger numbers might be stabilized if strict measures are taken to protect tigers and their prey from seasonal hunting and to suppress illegal trade in wildlife. Efforts to monitor abundance trends in the tiger population will be expensive given the difficulty with which tiger data can be obtained and the lack of available surrogate indices of tiger density. Monitoring occupancy patterns, the subject of a separate ongoing study, may be more efficient.  相似文献   

7.
Very little is known about prey selection by the Indian tiger Panthera tigris tigris in tropical dry deciduous forests or in wild herbivore-depleted habitats with high livestock pressures. We undertook a short-term study in a large south Indian tiger reserve and examined two intensive study areas (SA's) from October 1998 – June 1999. In each area, herbivore sightings were recorded, scats were collected, and wild prey and livestock kills documented. Chital, wild boar and sambar were the most abundant among the wild herbivores in the study area. Scat analysis revealed wild boar (Sus scrofa) being the most common prey followed by chital (Axis axis) and sambar (Rusa unicolor). Livestock comprised less than 7% of diet intake. Here, the tigers consumed a lower mean prey mass (56.3 kg) than in other reserves. Our study suggests that in tropical dry deciduous forests with low natural prey density, smaller prey species, and high livestock biomass, tigers preferentially kill smaller prey and generally avoid livestock predation.  相似文献   

8.

Background

Tiger populations are dwindling rapidly making it increasingly difficult to study their dispersal and mating behaviour in the wild, more so tiger being a secretive and solitary carnivore.

Methods

We used non-invasively obtained genetic data to establish the presence of 28 tigers, 22 females and 6 males, within the core area of Pench tiger reserve, Madhya Pradesh. This data was evaluated along with spatial autocorrelation and relatedness analyses to understand patterns of dispersal and philopatry in tigers within this well-managed and healthy tiger habitat in India.

Results

We established male-biased dispersal and female philopatry in tigers and reiterated this finding with multiple analyses. Females show positive correlation up to 7 kms (which corresponds to an area of approximately 160 km2) however this correlation is significantly positive only upto 4 kms, or 50 km2 (r  = 0.129, p<0.0125). Males do not exhibit any significant correlation in any of the distance classes within the forest (upto 300 km2). We also show evidence of female dispersal upto 26 kms in this landscape.

Conclusions

Animal movements are important for fitness, reproductive success, genetic diversity and gene exchange among populations. In light of the current endangered status of tigers in the world, this study will help us understand tiger behavior and movement. Our findings also have important implications for better management of habitats and interconnecting corridors to save this charismatic species.  相似文献   

9.
Genetically engineered pacemaking in ventricular cells has been achieved by down-regulation of the time independent inward rectifying current (I K1), or insertion of the hyperpolarisation-activated funny current (I f). We analyse the membrane system (i.e. ionic concentrations clamped) of an epicardial Luo-Rudy dynamic cell model using continuation algorithms with the maximum conductance () of I K1 and I f as bifurcation parameters. Pacemaker activity can be induced either via Hopf or homoclinic bifurcations. As K1 is decreased by ≈74%, autorhythmicity emerged via a homoclinic bifurcation, i.e., the periodicity first appear with infinitely large periods. In contrast, the insertion of f induced periodicity via a subcritical Hopf bifurcation at f≈ 0.25 mSμF−1. Stable autorhythmic action potentials occurred at f > 0.329 mSμF−1.  相似文献   

10.
Density of tiger Panthera tigris and leopard Panthera pardus was estimated using photographic capture–recapture sampling in a tropical deciduous forest of Mudumalai Tiger Reserve, southern India, from November 2008 to February 2009. A total of 2,000 camera trap nights for 100 days yielded 19 tigers and 29 leopards within an intensive sampling area of 107 km2. Population size of tiger from closed population estimator model Mb Zippin was 19 tigers (SE = ±0.9) and for leopards Mh Jackknife estimated 53 (SE = ±11) individuals. Spatially explicit maximum likelihood and Bayesian model estimates were 8.31 (SE = ±2.73) and 8.9 (SE = ±2.56) per 100 km2 for tigers and 13.17 (SE = ±3.15) and 13.01 (SE = ±2.31) per 100 km2 for leopards, respectively. Tiger density for MMDM models ranged from 6.07 (SE = ±1.74) to 9.72 (SE = ±2.94) per 100 km2 and leopard density ranged from 13.41 (SE = ±2.67) to 28.91 (SE = ±7.22) per 100 km2. Spatially explicit models were more appropriate as they handle information at capture locations in a more specific manner than some generalizations assumed in the classical approach. Results revealed high density of tiger and leopard in Mudumalai which is unusual for other high density tiger areas. The tiger population in Mudumalai is a part of the largest population at present in India and a source for the surrounding Reserved Forest.  相似文献   

11.
The production of dicentric chromosomes in human lymphocytes by high-energy neutron radiation was studied using a quasi-monoenergetic 60 MeV neutron beam. The average yield coefficient of the linear dose–response relationship for dicentric chromosomes was measured to be (0.146±0.016) Gy−1. This confirms our earlier observations that above 400 keV, the yield of dicentric chromosomes decreases with increasing neutron energy. Using the linear-quadratic dose–response relationship for dicentric chromosomes established in blood of the same donor for 60Co γ-rays as a reference radiation, an average maximum low-dose RBE (RBEM) of 14±4 for 60 MeV quasi-monoenergetic neutrons with a dose-weighted average energy of 41.0 MeV is obtained. A correction procedure was applied, to account for the low-energy continuum of the quasi-monoenergetic spectral neutron distribution, and the yield coefficient α for 60 MeV neutrons was determined from the measured average yield coefficient . For α, a value of (0.115±0.026) Gy−1 was obtained corresponding to an RBEM of 11±4. The present experiments extend earlier investigations with monoenergetic neutrons to higher energies.  相似文献   

12.
A decade back, almost 300,000 km2 of forests in India were estimated to be potential tiger habitat. But consistent degradation and unsustainable anthropogenic pressures have adversely affected tiger presence in most of the forests outside the better protected tiger reserves. Here we use Geographic Information System data to analyze the degree of vegetation loss and landscape changes over the last decade (1998–2006), and ascertain the presence of tigers in a degraded forest like the Kawal Wildlife Sanctuary, Andhra Pradesh, India, by non-invasive fecal DNA analysis. Vegetation cover maps show a clear degradation of the sanctuary within a decade. DNA analysis of scat samples reveals tiger presence in areas where closed dense forest canopy has persisted with minimal human disturbance during the last decade.  相似文献   

13.
For long-lived iteroparous vertebrates that annually produce few young, life history theory predicts that reproductive output (R) and juvenile survival should influence temporal variation in population growth rate (λ) more than adult survival does. We examined this general prediction using 15 years of mark–recapture data from a population of California spotted owls (Strix occidentalis occidentalis). We found that survival of individuals ≥1 year old (ϕ) exhibited much less temporal variability , where CV is coefficient of variation, than R and that R was strongly influenced by environmental stochasticity. Although λ was most sensitive ( ; log-transformed sensitivity) to ϕ and much less sensitive to either R or juvenile survival (survival rate of owls from fledging to 1 year old; ), we estimated that R contributed as much as ϕ to the observed annual variability in λ. The contribution of juvenile survival to variability in λ was proportional to its These results are consistent with the hypothesis that natural selection may have favored the evolution of longevity in spotted owls as a strategy to increase the probability of experiencing favorable years for reproduction. Our finding that annual weather patterns that most affected R (temperature and precipitation during incubation) and ϕ (conditions during winter related to the Southern Oscillation Index) were equally good at explaining temporal variability in λ supports the conclusion that R and ϕ were equally responsible for variability in λ. Although currently accepted conservation measures for spotted owl populations attempt to enhance survival, our results indicated that conservation measures that target R may be as successful, as long as actions do not reduce ϕ.  相似文献   

14.
The self-complementary subset ∪{AAA,TTT} with = {AAC, AAT, ACC, ATC, ATT, CAG, CTC, CTG, GAA, GAC, GAG, GAT, GCC, GGC, GGT, GTA, GTC, GTT, TAC, TTC} of 22 trinucleotides has a preferential occurrence in the frame 0 (reading frame established by the ATG start trinucleotide) of protein (coding) genes of both prokaryotes and eukaryotes. The subsets ∪{CCC} and ∪{GGG} of 21 trinucleotides have a preferential occurrence in the shifted frames 1 and 2 respectively (frame 0 shifted by one and two nucleotides respectively in the 5′-3′ direction). and are complementary to each other. The subset contains the subset which has the rarity property (6 × 10−8) to be a complementary maximal circular code with two permutated maximal circular codes and in the frames 1 and 2 respectively. is called a C3 code. A quantitative study of these three subsets in the three frames 0, 1, 2 of protein genes, and the 5′ and 3′ regions of eukaryotes, shows that their occurrence frequencies are constant functions of the trinucleotide positions in the sequences. The frequencies of in the frame 0 of protein genes are 49, 28.5 and 22.5% respectively. In contrast, the frequencies of in the 5′ and 3′ regions of eukaryotes, are independent of the frame. Indeed, the frequency of in the three frames of 5′ (respectively 3′) regions is equal to 35.5% (respectively 38%) and is greater than the frequencies and , both equal to 32.25% (respectively 31%) in the three frames. Several frequency asymmetries unexpectedly observed (e.g. the frequency difference between and in the frame 0), are related to a new property of the subset involving substitutions. An evolutionary analytical model at three parameters (p, q, t) based on an independent mixing of the 22 codons (trinucleotides in frame 0) of with equiprobability (1/22) followed by t ≈ 4 substitutions per codon according to the proportions p ≈ 0.1; q ≈ 0.1 and r = 1 − pq ≈ 0.8 in the three codon sites respectively, retrieves the frequencies of observed in the three frames of protein genes and explains these asymmetries. Furthermore, the same model (0.1, 0.1, t) after t ≈ 22 substitutions per codon, retrieves the statistical properties observed in the three frames of the 5′ and 3′ regions. The complex behaviour of these analytical curves is totally unexpected and a priori difficult to imagine.  相似文献   

15.
The electrochemical potential differences for potassium, between excised barley (Hordeum vulgare L.) roots and external media containing 0.05 mM KCl+0.5 mM CaSO4, were determined over a 4-h period during which initially low-K+ roots accumulated K+ by pretreatment in 50 mM KCl plus 0.5 mM CaCl2. This pretreatment resulted in increased internal [K+], decreased K+ influx (as measured from 0.05 mM KCl+0.5 mM CaSO4) and decreased values of . These observations indicate that the decline of K+ influx associated with increased internal K+ concentration cannot be accounted for by passive adjustment to the electrochemical gradient for this ion.  相似文献   

16.
Summary In dynamic light scattering, measurements of the intensity-intensity time correlation function from a suspension of rod-like particles of length L could reveal dynamical information related to translational and internal motions of those particles. For a suspension of thick filaments isolated from the myosin-regulated, striated muscles of Limulus at KL>1 (where K is the scattering vector), the average characteristic linewidth ( ) increased with the addition of Ca2+ or with the depletion of ATP. The increase in the with the addition of Ca2+ could be due to the presence of energy-requiring, high-frequency motions of the crossbridges activated by Ca2+. The increase in which occurred with the depletion of ATP was assumed to be mainly due to the thermal motions of the crossbridges after they had moved radially away from the filament backbone. The percentage increase in following the addition of Ca2+ was found to be seasonal, i.e., values of obtained from thick filaments isolated between the middle of June and the middle of September were smaller than those obtained during the rest of the year. The effect of temperature on the percentage increase in was also different. The increase showed a maximum at about 35°C during the summer and at about 25°C at other times. However, the percentage increase in developed under ATP-depleted conditions showed no temperature-related maximum. The number of bound Ca2+ per myosin molecule was 1 during the summer and 2 at other times.Abbreviations DLS dynamic light scattering - L length - K scattering vector - SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis - average characteristic line width Deceased  相似文献   

17.
During a survey of Guatemalan herpetofauna in the summers of 1998–2000, 29 presumed new species of Eimeria Schneider, 1875 were found, seven of which have a distinct elongate-ellipsoidal shape (L/W ratio ≥ 1.7) and are described herein. Six of the seven new species are similar in oöcyst length, width and L/W ratio and sporocyst length, width and L/W ratio, lack a micropyle, oöcyst residuum, Stieda body, sub- and parastieda bodies, have a polar granule and sporocyst residuum, and their sporocysts appear to have dehiscence sutures. The seventh is slightly smaller and has sporocysts with a Stieda body. The new species are: E. coniophanes n. sp – whose sporulated oöcysts from Coniophanes fissidens are 29.2×14.9 (27–31×13–16) m, with sporocysts m; E. coniophis n. sp. –from Conophis lineatus are 32.0×16.5 (30–34×14–18) m, with sporocysts m; E. dryomarchoni n. sp. – from Drymarchon corais are 32.2×17.7 (31–34×17–19) m, with sporocysts m; E. leptophis n. sp. – from Leptophis mexicanus are 29.5×17.0 (28–31×16–18) m, with sporocysts m; E. oxybelis n. sp. – from Oxybelis aeneus are 31.8×16.5 (29–33×15–18) m, with sporocysts m; and E. scaphiodontophis n. sp. – from Scaphiodontophis annulatus are 30.0×15.3 (28–33×14–16) m, with sporocysts m. Sporulated oöcysts of E. siboni n. sp. from Sibon nebulata are 24.3×14.2 (21–27×13–16) m, with sporocysts m and with a Stieda body. We conclude that until all aspects of each life-cycle are known, it is prudent at this time to name all tetrasporocystic dizoic coccidia from snakes as members of Eimeria rather than place some of them in Choleoeimeria Paperna & Landsberg, 1989.  相似文献   

18.
An extremely high-density (ca. 800 deer km–2) wild sika deer population uses a short-grass community dominated by Zoysia japonica on Kinkazan Island in northeastern Japan. To explain why the density of wild deer is quite high on the Zoysia community, (1) we quantified the seasonal productivity of the Zoysia community, (2) we compared food availabilities among the plant communities, and (3) we described the habitat selection by the deer in different seasons. Food availability was greater on the Zoysia community than in the forest understory from spring to fall. The productivity of the Zoysia community was high enough to support the actual high density of the deer (814 deer km–2) in summer. However, the productivity markedly decreased in winter, when the deer density decreased to less than half (358 deer km–2) of the summer value. In contrast, the deer density of the adjacent forests was highest in winter (154 deer km–2) and lowest in spring (19 deer km–2). These results suggest that the deer using the Zoysia community in summer left and were absorbed into the adjacent forest in winter. If such an adjacent community were absent, many deer would not survive, and consequently the deer density on the Zoysia community in summer would not be so high. This intercommunity movement is particularly important for the deer using a plant community like the Zoysia community, which is highly productive but has a small standing biomass.  相似文献   

19.
Quantifying foliar stable carbon isotope discrimination (Δ) is a powerful approach for understanding genetic variation in gas exchange traits in large populations. The genetic architecture of Δ and third-year height is described for more than 1,000 clones of Pinus taeda tested on two contrasting sites. for Δ was 0.14 (±0.03), 0.20 (±0.07), and 0.09 (±0.04) at Florida, Georgia, and across sites, respectively. for stable carbon isotope discrimination ranged from 0.25 (±0.03) at the Florida site to 0.33 (±0.03) at the Georgia site, while the across-site estimate of was 0.19 (±0.02). For third-year height, ranged from 0.13 (±0.05) at the Georgia site to 0.20 (±0.06) at the Florida site with an across-site estimate of 0.09 (±0.05). Broad-sense heritability estimates for third-year height were 0.23 (±0.03), 0.28 (±0.03), and 0.13 (±0.02) at the Florida site, Georgia site, and across sites, respectively. Type B total genetic correlation for Δ was 0.70 ± 0.06, indicating that clonal rankings were relatively stable across sites, while for third-year height, rankings of clones were more unstable across the two trials . Third-year height and Δ were negatively correlated at the parental , full-sib family , and clonal levels, suggesting that genetic variation for Δ in P. taeda may be a result of differences in photosynthetic capacity. We conclude that Δ may be a useful selection trait to improve water-use efficiency and for guiding deployment decisions in P. taeda.  相似文献   

20.
In a randomly selected sample of 88 men and 115 women, aged 23–27 years from Denmark, maximal oxygen uptake ( O2max), maximal voluntary isometric contraction (MVC) in four muscle groups and physical activity were studied. The O2max was 48.0 ml · min–1 kg–1 and 39.6 ml · min–1 · kg–1 for the men and the women, respectively. The MVC was 10% lower than in a comparable group of Danes of the same age and height studied 35 years ago. Only in men was sports activity directly related to O2max (ml · min–1 · kg–1; r=0.31, P<0.01). The MVC of the knee extensors was related to O2max in the men (r=0.31, P<0.01), but there was no relationship between the other measurements of MVC and O2max. In the women O2max (ml · min–1 · kg–1) was only related to body size, i.e. body mass index, percentage body fat and body mass [(r= –0.47, –0.48 (both P<0.001) and –0.34. (P<0.01), respectively)]. There were differences in O2max in the men, according to education and occupation. Blue collar workers and subjects attending vocational or trade schools in 1983 had lower O2max and more of them were physically inactive. In the women differences were also found, but there was no clear pattern among the groups. More of the women participated regularly in sports activity, but more of the men were very active compared to the women.  相似文献   

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