首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Results of stationary studies on the spatial location of sables (Martes zibellinaL.) belonging to different age and sex groups are summarized. Mapping the sites where 388 animals were taken, it was found that young animals tended to live near floodplains; adult animals, on watersheds. Analysis of sables taken by commercial hunters (n= 1833) made it possible to estimate the age composition and the degree and spatial distribution of the hunting pressure on sable populations in three areas of the Ob region. The spatial separation of young and reproductive animals is interpreted as a group adaptive response to the specific distribution pattern of different habitats typical of this species and to the pattern of animal elimination. It is proposed to use the specific pattern of animal distribution for maintaining the size of the population that is subject to hunting. Specifically, reserve (reproductive) territories should be organized in watershed areas.  相似文献   

2.
An abnormal cranial variation in the sable (Martes zibellinaL.) from the extreme Russian Northeast was studied. In the populations formed as a result of reacclimation, the proportion of animals with morphological cranial anomalies proved to be significantly higher than in the parental populations (from which the animals for reintroduction were taken). Probable factors responsible for this effect are discussed.  相似文献   

3.
The degree of morphological differentiation of sable (Martes zibellina L.) populations was studied in different physiographic regions of the Kamchatka Peninsula and the Penzhina River basin. According to craniometric data, the sables inhabiting the hilly Western Kamchatka Plain are larger than the animals from other regions. However, the analysis of phenetic variation in craniological characters and coat color showed that the sable samples taken within the peninsula were fairly homogeneous. On this basis, all sables inhabiting the Kamchatka Peninsula may be regarded as a single population.  相似文献   

4.
The contents of the digestive tract in sables (Martes zibellina L.) of known sex and age from the Middle Kolyma basin were examined to assess the winter diet in general and the frequencies of particular types of food in different sex and age groups of these animals. No statistically significant sex-related differences in the diet were revealed. This is probably explained by a considerable overlap of size and weight parameters between male and female Kolyma sables, due to which probable differences in their diets are leveled off.  相似文献   

5.
Studies on the population structure and dynamics of the stone centipede Monotarsobius curtipes C. Koch in soils of the northern Kola Peninsula have shown that, with respect to abundance and biomass, this species is a dominant of the soil macrofauna and, in particular, of the trophic group of zoophages. Life in high northern latitudes does not disturb the sex and age structure of populations but limits the reproductive activity of these centipedes. Specific biological features of M. curtipes at the northern periphery of its range include the absence of repeated breeding, completion of several developmental (age) stages within a short growing season, and long ontogeny involving several winterings.  相似文献   

6.
Body size-dependent mating pattern is thought to a consequence of the sexual selection on phenotypic characters. In the view, we investigated the mating patterns in Bufo andrewsi from three populations at different latitude in three Nature Reserves (i.e. Wanglang, Yele and Fengtongzhai) in China from early- March to late-May 2013 and 2014. The results showed that average body size did not differ significantly between amplectant and non-amplectant males within each population. We found a significantly positive relationship in body size between the amplectant males and amplectant females in Wanglang population, but not in Qiqiao and Yele populations. The strength of size-dependent mating was not correlated with the malebiased operational sex ratios (OSRs), suggesting that intensity of male-male competition at nights do not result in variation in size-dependent mating patterns in B. andrewsi among populations.  相似文献   

7.
Natural vegetation and native plant species contribute significantly to the daily needs of local people especially in developing countries. This exerts a high pressure on local species and jeopardizes the conservation of the most vulnerable plants. In Burkina Faso, conservation measures, such as the creation of protected forests, have been taken to safeguard the remaining indigenous vegetation. However, little is known about the effectiveness of these protected areas in conserving biodiversity. This study assessed and compared the population structures and regeneration potential of three vulnerable woody species—Diospyros mespiliformis Hochst., Prosopis africana (Guill. & Perr.) Taub. and Sterculia setigera Del.—in protected and unprotected areas in the Sudanian zone of Burkina Faso. The population structure and regeneration pattern of each species were compared between the North and South Sudanian sectors of Burkina Faso. The populations of all three species were unstable in both protected and unprotected areas. D. mespiliformis and P. africana displayed relatively good regeneration while P. africana lacked regeneration in unprotected areas. Regeneration was poor for S. setigera, regardless of protection status. The results suggest that the populations of the targeted species are unstable, regardless of the protection status of the area considered. This is probably due to the high anthropogenic pressure facing natural resources and raises serious concerns about the effectiveness of the protected areas in conserving biodiversity. Urgent measures are needed to ensure effective and efficient management and conservation of biodiversity in the protected areas of Burkina Faso.  相似文献   

8.
Quantitative parameters of cenopopulations of Lobaria pulmonaria, an endangered cyanolichen, have been studied in spruce phytocenoses of Karelia recovering after disturbance through the successional stage of aspen stands for a period ranging from 80 to 450 years. The results show that, as the time since disturbance increases, the total number of L. pulmonaria thalli and the number of colonized substrate units increase as well, with no stabilization of these parameters being observed in the series of communities studied. The total area of thalli in the phytocenoses is restored within approximately 200 years after the last disturbance. In old-growth forests (>400 years), L. pulmonaria thalli colonize a broad spectrum of tree species in different life states, including lower branches of young spruce trees. Even if they serve as temporary substrates, this can markedly strengthen the potential of the species for further expansion within the community in case of shortage in the main phorophyte (aspen). Thus, the proportion of regressive populations decreases, while that of colonizing populations increases, which is indicative of successful reproduction of the species.  相似文献   

9.
Samples of small rodent populations inhabiting Crabapple Island on Beldany Lake in NE Poland revealed that Clethrionomys glareolus was continously present there, whereas Apodemus flavicollis and Microtus agrestis appeared, stayed for some period, vanished and reappeared. It appears that sexually mature females of the bank vole are strictly territorial, their numbers are limited, and immature individuals hardly disperse at high population size. Sexually mature females of the yellow-necked mouse seem to be territorial only at low population numbers, and their numbers increase linearly with population size. Sexually mature females of the field vole exhibit high level of aggregation, and their numbers increase in streight line with growing population size. We discuss the idea that different social organization of the rodent populations is connected with various strategies (sedentary and nomadic) supporting local population persistence.  相似文献   

10.
The spatial structure of 10 populations of rare orchid species (Dactylorhiza incarnata, D. traunsteineri, Listera ovata) has been studied in rich fens sporadically occurring in Murmansk oblast. Two levels of plant aggregation within populations have been distinguished: (1) clusters of individuals and (2) isolated population subsets consisting of clusters. General spatial demographic features of orchid populations in the fens are small area (77 m2) and low ecological density (0.009 ind./m2). Characteristics of the population subsets (their number, area, composition, and distance to the neighboring subset) are species-specific and reflect the degree of species rarity in plant communities.  相似文献   

11.
Methods of geometric morphometrics and population phenogenetics have been used to evaluate morphogenetic rearrangements in two sympatric species of Myodes voles (M. glareolus Schreb. 1780 and M. rutilus Pall. 1779) from syntopic populations recovering after exposure to local “ecological vacuum” created as a result of rodent extermination in a natural focus of hemorrhagic fever in the southern taiga subzone of the Udmurt Republic. The model used in the study simulates the situation that arises upon nonselective elimination of rodent populations and communities in spring and their subsequent recovery. Analysis of variation in the size and shape of the mandible and in a complex of 30 nonmetric cranial characters has revealed similar (parallel) and species-specific morphogenetic and epigenetic changes occurring during the recovery of local rodent community. Species-specific differences in the pattern of change in the parameter characterizing within-group morphological disparity in the mandible shape (MNND) have been revealed between the dominant species (M. glareolus) and the subdominant species competing with it for territory (M. rutilus). Different reactions of close Myodes species in the course of filling the ecological vacuum are considered as a result of reduction in the level of competition for the subdominant species and a compensatory increase of morphological disparity in the dominant species under conditions of low density and incomplete composition of the community, in accordance with Chernov’s (2005) ecological compensation principle.  相似文献   

12.
Long-term dynamics of population decline can improve the conservation perspectives and strategies for endanger species. In China, new gazetteers having systematic compilation and wide geographical coverage can be considered as an important complementary for reconstruction historical distribution. For historical and cultural reasons, an endangered species–lynx (Lynx lynx) was recorded regularly in new gazetteers. Therefore, the aim of this paper was to evaluate the population distribution in Northeast China from the 1950s to 2014. The data show that Felis lynx was widely distributed in Northeast China in the 1950s, but the number of the occurrence records have been significantly reduced by 85.6% in the last 60 years. This research also enlightens us that the new gazetteers can contribute to data shortage and it would be helpful to conservation biology.  相似文献   

13.
To characterise indirect effects of ionising radiation on aquatic microbial communities, effects of acute γ-irradiation were investigated in a microcosm consisting of populations of green algae (Chlorella sp. and Scenedesmus sp.) and a blue-green alga (Tolypothrix sp.) as producer; a ciliate protozoan (Cyclidium glaucoma), rotifers (Lecane sp. and Philodina sp.) and an oligochaete (Aeolosoma hemprichi) as consumer; and more than four species of bacteria as decomposers. Population changes in the constituent organisms were observed over 160 days after irradiation. Prokaryotic community structure was also examined by denaturing gradient gel electrophoresis (DGGE) of 16S rDNA. Principle response curve analysis revealed that the populations of the microcosm as a whole were not significantly affected at 100 Gy while they were adversely affected at 500-5000 Gy in a dose-dependent manner. However, some effects on each population, including each bacterial population detected by DGGE, did not depend on radiation doses, and some populations in the irradiated microcosm were larger than those of the control. These unexpected results are regarded as indirect effects through interspecies interactions, and possible mechanisms are proposed originating from population changes in other organisms co-existing in the microcosm. For example, some indirect effects on consumers and decomposers likely arose from interspecies competition within each trophic level. It is also likely that prey-predator relationships between producers and consumers caused some indirect effects on producers.  相似文献   

14.
The formation of the spatial structure of the willow warbler (Phylloscopus trochilus) and little bunting (Emberiza pusilla) populations differing in the degree of site fidelity was studied. The area populated by each species was subdivided according to how regularly its parts had been populated over a 16-year period and how synchronous the population dynamics were. The validity of some hypotheses detailing the population formation was tested by comparing simulated population dynamic curves in segments differing in quality with actual curves.  相似文献   

15.
Study of the seasonal variation of the sex ratio in the honeybee mite Varroa jacobsoni demonstrated that sex determination was affected by temperature, order of reproductive cycles, and population densities in the host’s brood cell and the honeybee nest. The mechanism of reproduction ensuring adaptation of the mite to parasitism and reproduction on honeybees are discussed.  相似文献   

16.
大别山五针松种群结构及动态研究   总被引:3,自引:0,他引:3  
大别山五针松(Pinus dabeshanensis)是大别山区特有种,最大种群分布于安徽省岳西县大王沟。采用空间序列代替时间的方法分析种群结构,编制种群特定时间生命表,绘制死亡率曲线和消失率曲线,并用4个生存函数进行种群的生存分析;同时结合谱分析方法,分析了大别山五针松种群数量的动态变化。结果表明:大别山五针松种群数量少,结构存在波动性。幼苗阶段个体较丰富,幼树阶段个体较少,种群趋于衰退。种群死亡率和消失率曲线变化趋势基本一致,在第5龄级出现峰值。4个生存函数曲线表明,大别山五针松具有前期快速减少、中期稳定和后期衰退的特点。谱分析显示,大别山五针松种群动态除受基波影响外,还具有明显的小周期波动,谐波A3和A4处的周期波动与个体生长有关。  相似文献   

17.
Sex-biased predation is thought to have important implications for sexual selection, sex allocation, and population dynamics (Magnhagen, 1991; Le-Galliard et al., 2005 for an example in lizards). Most studies found that males are subjected to higher predation pressure than females during the reproductive season (Korpimäki, 1985; Lodé et al., 2004; Christe et al., 2006; Costantini et al., 2007). In that period, males are very mobile, emit acoustic signals and exhibit brilliant colourations, which are needed to attract females but may make them more visible to predators. With regard to lizards, a recent study provided the first evidence that males of a lizard species may be preyed on more than females (Costantini et al., 2007). In the present study, we investigated whether there is sex-biased predation on two small lacertid species, the common wall lizard Podarcis muralis (Laurenti, 1768) and the Italian wall lizard Podarcis sicula (Rafinesque-Schmaltz, 1810), by Eurasian kestrels (Falco tinnunculus) during the reproductive season. We also examined whether (1) the rate of predation differed between species and (2) the rate of predation differed across years or among hunting habitats for each species.  相似文献   

18.
The phylogenogeographic structure, polymorphism, and differentiation of Pinus sylvestris L. have been studied for the first time by means of allozyme analysis of 143 populations along a network of transects covering the entire species range. The results show that the species in general is characterized by a significant level of differentiation, regardless of its relative uniformity in northern and central parts of the range. Nei??s genetic distances between populations and their gradients in the extreme southern parts of the range, where it has an insular pattern, are seven to eight times greater than in the northern, ??glacial?? zone. Three Pleistocene refugia for the species have been revealed in the Balkans, Southern Urals, and Northern Mongolia. Using analysis of genetic distances between 18 phylogeographic regions and an original genosystematic scale, one subspecies, five geographic races and nine geographic population groups have been distinguished in the P. sylvestris L. species structure.  相似文献   

19.
Arunachal Pradesh in northeastern India is considered a biocultural diversity hotspot, with diverse tribal peoples and immense floral and faunal diversity. This rich diversity, sustained through the morang (community forests) and jhum (slash and burn) cultivation systems, is the backbone of native communities’ livelihood security. Kebung (Ratufa bicolor) and other squirrel species are intricately related to biocultural systems of the Adi people of Arunachal Pradesh. Primary surveys and participatory rural appraisals were carried out in 20 villages of East Siang and Upper Siang districts of the state. Results indicated that Kebung squirrels are hunted from successional forests, including from morang and jhum lands. They are an integral part of the Adi sociocultural, economic and livelihood systems, being used for food, medicinal, ceremonial and other purposes. Hunting methods vary in the traditional and transitional Adi villages. Recently, kebung populations have diminished, and this is attributed to overhunting. In particular, a decrease in kebung populations in some morang and jhum habitats has threatened the biocultural resources of the Adi. Knowledge and management practices relating to kebung hunting are gradually eroding among the younger Adi generations. However, the community recently passed a resolution for kebung conservation, supported by the customary norms. We conclude with a discussion of policy requirements for sustainable management of kebung populations to maintain Adi biocultural and livelihood security.  相似文献   

20.
The increased variability in weather as a manifestation of climate change is expected to have negative impacts on population survival in wildlife species, because it will likely lead to increased variation in vital demographic rates (mortality and reproduction) in these populations. For the effective protection of biodiversity, adaptation measures are needed to compensate for the expected increase in weather variability and the negative interaction with habitat fragmentation. As a case study, we studied the fluctuations in Great Bittern numbers (Botaurus stellaris) from 28 monitoring plots scattered over the Netherlands to explore the interaction between the effect of weather and possible remediating effects of the landscape structure. Great Bittern habitat surrounding these plots differs with respect to area, quality, and degree of isolation of this habitat. In western Europe, Great Bitterns are found to be susceptible to continuous loss of suitable habitat due to vegetation succession and fragmentation. Moreover, year-to-year fluctuations in local Great Bittern populations can be caused by severe winter weather or other weather extremes. Our results show that severe winter weather has indeed a significant negative impact on Great Bittern population growth rates. Furthermore, we found that an increased carrying capacity and spatial cohesion (i.e. inverse of habitat fragmentation) contribute to an increase in mean growth rates over the years. As growth rates are higher in large, well-connected habitats, we argue that recovery from negative effects of, e.g. severe winters on Great Bittern population numbers is enhanced in these less-fragmented habitats. We derived generic adaptation measures for enhancing the recovery rate of populations of species in general: one should invest in more large, well-connected nature areas, not only to diminish the negative effects of habitat fragmentation on wildlife populations, but additionally to reduce the impacts of climatic variability.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号