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1.
The phenetic structure of natural and urbanized populations of the terrestrial snail Cepaea vindobonensis has been studied with respect to polymorphism in the shell-band color and pattern. It is noted that C. vindobonensis snails populating different artificial habitats in the city of Nikolaev and its suburbs are characterized by a higher level of both intra-and interpopulation diversity with respect to the type of this polymorphism. In addition, urban populations show a very wide range of variation in the frequencies of particular morphs or their groups. Conversely, natural populations are characterized by a more uniform frequency structure with respect to polymorphism of the shell banding pattern.  相似文献   

2.
Data on the parameters of migration of two land snails of the genus Xeropicta are presented. In relatively homogeneous habitats, the locomotor activity of these mollusks is relatively high: they can travel for up to 300 cm per day, with neither the phenotype nor size of the shell having any significant influence on the level of dispersal. The snails prefer to travel westward and southward, but the distances covered by individuals moving in different directions are similar. No connection between the directions or distances of movement on two successive days has been observed.  相似文献   

3.
The species composition and inversion structure of Anopheles micropopulations have been studied in the environs of Teletskoye Lake, the Altai Republic. Two Anopheles species, A. messeae and A. beklemishevi, have been identified cytogenetically: Their zonal distribution has been determined, reflecting specific climatic features in the southern and northern parts of the lake. Intraspecific chromosomal polymorphism has been revealed in both mosquito species, with the inversion and karyotypic diversity being higher in the southern larval populations of A. messeae.  相似文献   

4.
The functioning of two foci of helminth diseases caused by trematodes Apophallus muehlingi and Rossicotrema donicum has been studied in the Volga Delta. The origin of these foci is related to the expansion of species ranges of Lithoglyphus snails, intermediate hosts of trematodes. Introduced mammal species, the raccoon dog Nyctereutes procyonoides and American mink Mustela vision, are involved in the circulation of the invasion.  相似文献   

5.
Allozyme analysis of 18 Pinus sylvestris L. populations from seven landscape-geographic groups has been performed in the Greater Caucasus, Crimea, and Russian Plain. The results show that populations of the Mt. Elbrus region (isolated by high mountain ridges) are characterized by lower polymorphism and most distinct differentiation (at the level of geographic race) from other populations, which are differentiated from each other at the level of geographic groups. Genetic gradients (boundaries) between populations reach a maximum on transects across the Greater Caucasus Range, and Transcaucasian populations are more similar to populations of the Russian Plain, compared to North Caucasian populations, which confirms the hypothesis of ancestral connections between their gene pools.  相似文献   

6.
(137)Cs, (85)Sr, (133)Ba and (123m)Te contaminations of terrestrial gastropods, Helix aspersa maxima, by direct deposition, labelled food ingestion or combined (trophic and direct pathways) exposure were carried out under laboratory conditions. The aim of this study was to compare the three contamination pathways: direct, trophic and combined, in terms of individual mortality, radionuclide uptake, depuration and distribution in the tissues. An initial group of 30 snails (2 years old) was exposed to radioactive aerosols during a 20-h period. These aerosols were assumed to be representative of those that would be released during a nuclear accident occurring in a PWR. A second group of 50 snails (same age) was submitted to an ingestion of commercial food contaminated by the same aerosols, twice a week for 21 days (flour at a feeding rate of about 0.2g). A third group of 40 snails was submitted to a combined exposure: exposure to radioactive aerosols (20h), followed by ingestion of flour contaminated by the same aerosols, twice a week for 21 days. No significant difference between the three groups and a reference group of 10 snails was observed, neither in growth nor in mortality. Concerning the direct pathway, at the end of direct deposition (about 1 day after the beginning), cesium was the most bioavailable element, distributed rather homogeneously throughout the whole body (13% of the total Cs in all organs excepting the digestive system and 28% in the muscle). Strontium was measured in the shell (about 70%). Barium was found in the muscle (20%) and in the shell (65%). Tellurium was mainly present in the shell (70%) and in the digestive system (20%). After 21 days of depuration, the faeces eliminated 42% of the Te. As for contamination by ingestion, Te mainly accumulated in the digestive system (72% of Te present in the total body), Ba accumulated in the muscle (75%) and Sr in the shell (70%). Concerning contamination by combined pathways, at the end of the 21-day exposure, the 4 radionuclides had the same tendency as direct deposition. However, the effect of the trophic pathway was significant: it causes an 18% increase of Sr in the shell and an 7% increase of Cs in the digestive system in comparison to direct deposition, resulting in a final 86% in the shell and 27% in the digestive system.  相似文献   

7.
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   

8.
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   

9.
The geographic variation of the water vole Arvicola terrestris L. has been analyzed with respect to two linear combinations of craniometric characters with the highest additive heritability (h 2 = 0.59 and h 2 = 0.52). The greatest differences have been revealed between the territorially close montane and piedmont populations. The lowland and montane populations have proved to differ to the smallest extent, despite their spatial and altitudinal separation. Selection under extreme conditions that leads to similar phenotypic results may be based on the common genetic background of these populations, irrespective of considerable distances between them and different environmental conditions in their habitats.  相似文献   

10.
Energy metabolism and phosphorus excretion were studied in Littorina littorea and L. saxatilis snails from the White Sea. Some elemental components of the body were determined quantitatively, and the rates of oxygen consumption and phosphorus excretion were estimated. All parameters were calculated relative to dry body weight (mg). Daily expenditures for energy metabolism in Littorina spp. averaged 3.6 ± 1.1%, and those for phosphorus metabolism were approximately four times lower (about 1%), with the total phosphorus content averaging 0.8% dry body weight. The atomic ratio of consumed oxygen to excreted phosphorus for both species averaged O: P = 1164 ± 140.  相似文献   

11.
The allozyme analysis of six local populations of Pinus mugo Turra and six populations of P. sylvestris L. in the Ukrainian Carpathians, Swiss Alps, and Schwarzwald has shown a higher polymorphism and greater interpopulation differentiation of the Carpathian group of P. mugo populations compared to the Alpine group (Nei’s genetic distance DN 78 at the level of geographic population group is −0.023). A genetic differentiation of DN 78 = 0.049 between these populations, which are isolated by a distance of more than 1000 km, has been found. This confirms the existence of the subspecies P. mugo ssp. mugo and P. mugo ssp. uncinata in the Carpathians and Alps, respectively. The hypothesis is put forward that the former subspecies has been formed in the Balkans and the latter, in the Pyreneans. It has been demonstrated that regional populations and geographic groups of P. sylvestris are less differentiated than those of P. mugo.  相似文献   

12.
长江口泥螺的种群特征及其生态学意义   总被引:3,自引:0,他引:3  
2000年5月中、下旬对长江口南汇边滩泥螺种群进行了调查和统计分析,结果表明:泥螺种群呈聚集型分布;泥螺种群密度分别为21.2%/m^2和32.8/m^2;生物量分别为25.60g/m^2WW和44.89g/m^2WW或2.05g/m^2DW和3.49g/m^2DW;平均壳高分别为1.19cm和1.34cm,壳高日生长量为98.7um,月生长率达24.9%;种群分别以壳高1.00-1.20cm(47.06%)和1.20-1.40cm(40.90%)的种群占绝对优势;性成熟个体比例分别占32.4%和78.3%,整个泥螺种群处于生长期向繁殖期过渡阶段,壳高(H)与壳宽(B)、湿重(WW)、存水量(F1)、相对存水量(F2)与WW之间回归方程分别为:H=0.18043 1.2750*B、WW、0.4475*H^2.5128、F1=0.7602*WW-0.4661、F2=34.021*WW-8.666,相关显著,平均肥满度(0)和鲜出肉率(PF)分别为299.27%和62.15%,它们与WW呈负相关,回归方程分别为:0=347.08-38.11*WWt PF=105.74-34.72*WW,前者相关性较差,后者显著,2000年5月初泥螺旺发与水动力条件、营养盐累积及饵料密切相关;目前的人工捕捞水平不会导致泥螺资源种群的数量下降,反而有助于发挥泥螺种群的环境净化功能。  相似文献   

13.
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   

14.
The level of genetic diversity of 13 Chinese populations of S. rostratum was investigated using nine microsatellite loci. The genetic diversity of the Weisanlu population in Hebei province was the highest and the Hohhot population was the lowest. The genetic differentiation among the populations was highly significant (P < 0.001). A total of 68.54% of the total genetic variation of population was within populations, and the genetic variation between populations accounted for 31.46%. The long-distance dispersal of its seeds by human transport mainly resulted in the rapid dispersal of S. rostratum in China.  相似文献   

15.
In the Gurbantunggut Desert of Northwestern China, we surveyed the population structure and regeneration characteristics of six Haloxylon ammodendron plantations based on chronosequencing. The results showed that the age class of an individual H. ammodendron plant from youngest to oldest showed growth potential under the present environment. The optimal termination stage of H. ammodendron occurred at 20 years of age, which was accompanied by a regeneration phase at 17 years. The H. ammodendron plantations started to regenerate after 7 years. The maximal height and basal stem diameter of a grade III seedling reached 1.2 m and 1.9 cm in a 17-year-old plantation. In a 33-year-old plantation, the transformation rate of the seedling from grade I to grade III increased up to 92.3%. Although the seedling bank was plentiful in the plantations, the replenishment of the canopy was not continuous and timely. Therefore, measures to further the stability and sustainability of H. ammodendron plantation were necessary.  相似文献   

16.
The distribution of nine chloroplast DNA haplotypes in four insular North-Atlantic and four European coastal Atlantic populations of Calluna vulgaris in the glacial zone of the range has been analyzed in comparison with that in six marginal southern populations in the nonglacial zone of the Atlantic and Mediterranean regions. As a result, two hypothetical Pleistocene refugia (HPRs) for this C. vulgaris population group have been revealed, one in the Cévennes mountain range and the other in the Southern Alps (Trento). Judging from the 1–FST value, it has been found that the group of populations in the glacial Atlantic zone and adjacent European coastal Atlantic region is genetically similar to the HPR in the Cévennes at a highly significant level (p ≥ 0.999) and less similar to the HPR in Trento; however, it differs significantly from other Mediterranean and Atlantic populations. It has been concluded that the most probable hypothetical Pleistocene refugium for the recent C. vulgaris populations of the northeastern Atlantic and European coastal Atlantic regions was in the west of the Mediterranean, in the Cévennes, while the additional refugium was in the Southern Alps. Possible directions of the postglacial dispersal and recolonization of habitats by C. vulgaris populations from the western Mediterranean to the northeast of the Atlantic and to Scandinavia have been revealed.  相似文献   

17.
We employed ecologically using Mexh and Mori wavelet methods to analyze the cycle phenomena and their maintaining mechanisms of the Haloxylon ammodendron distribution in complex longitudinal sand ridges (CLSRS). The results showed that ecologically using wavelet can distinguish H. ammodendron distributed in parallel-shaped, lattice-shaped and fork-shaped dunes with a dominant cycle of 165–180 m, 100–110 m and 70–80 m, respectively. Besides the dominant cycle, ecologically using Mori wavelet also showed 2–3 minor small peaks on different scales. The mechanisms to maintain the cycles at multi-scales of H. ammodendron relies on the seed spread, interference intensity in different topography and soil properties. The formations, configurations and presences of the three types of dunes should have some direct relations with the wind fields of the areas where the patterns are located, and also with the ground surface conditions. If the distribution pattern is periodic, meanwhile the abrupt change points are significant; we can predict the H. ammodendron distribution pattern in a certain area.  相似文献   

18.
Populations of Haloxylon àphyllum in the Kyzylkum Desert have been found to be markedly deficient in heterozygotes at a medium level of genetic diversity (P 95 = 0.56, A = 1.67, H o = 0.14, H e = 0.28). Spatial genetic differentiation of these populations have been revealed along a soil salinity gradient (from 0 to 0.5 mmol Na+/g), with their genetic diversity reaching a maximum (H o = 0.21?C0.25, H e = 0.25?C0.27) in areas with a moderate salinity level (0.05?C0.1 mmol Na+/g). Locus Got-2 can serve as a marker of this differentiation (FstGot-2 = 0.4).  相似文献   

19.
Previous studies investigating the exposure to metal(loid)s of populations living in the Panasqueira mine area of central Portugal found a higher internal dose of elements such as arsenic, chromium, lead, manganese, molybdenum and zinc in exposed individuals. The aims of the present study were to evaluate the extent of genotoxic damage caused by environmental and occupational exposure in individuals previously tested for metal(loid) levels in different biological matrices, and the possible modulating role of genetic polymorphisms involved in metabolism and DNA repair. T-cell receptor mutation assay, comet assay, micronucleus (MN) test and chromosomal aberrations (CA) were performed in a group of 122 subjects working in the Panasqueira mine or living in the same region. The modifying effect of polymorphisms in GSTA2, GSTM1, GSTP1, GSTT1, XRCC1, APEX1, MPG, MUTYH, OGG1, PARP1, PARP4, ERCC1, ERCC4, and ERCC5 genes was investigated. Significant increases in the frequency of all biomarkers investigated were found in exposed groups, however those environmentally exposed were generally higher. Significant influences of polymorphisms were observed for GSTM1 deletion and OGG1 rs1052133 on CA frequencies, APEX1 rs1130409 on DNA damage, ERCC1 rs3212986 on DNA damage and CA frequency, and ERCC4 rs1800067 on MN and CA frequencies. Our results show that the metal(loid) contamination in the Panasqueira mine area induced genotoxic damage both in individuals working in the mine or living in the area. The observed effects are closely associated to the internal exposure dose, and are more evident in susceptible genotypes. The urgent intervention of authorities is required to protect exposed populations.  相似文献   

20.
Reproductive behaviour of clonal plants might change in contrasting habitats. In field and simulated experiments, we studied the relative importance of sexual reproduction and clonal propagation in rhizomatous herb, Iris japonica Thunb. in two forest habitats (BF, bamboo forest and OAFE, open area of forest edge), and effects of population origin (BF vs. OAFE) and environmental effects (shading) on sexual vs. clonal reproduction. In field experiment, the relative importance of reproduction in I. japonica populations was different in two habitats, which showed predominantly sexual reproduction in OAFE and clonal propagation in BF. In simulated experiment, the effect of population origin and light treatment (shading) was significant for reproduction of I. japonica. Clonal propagation was only influenced by population origin, and sexual reproduction was determined both by population origin and light treatment. A trade-off between two reproductive modes exhibited in both experiments. The trade-offs was more obvious in OAFE than in BF because sexual reproduction, resource and inter-specific competition obviously lacked in BF. The results indicated that the selective forces shaping reproduction of I. japonica in contrasting habitats might demonstrate pronounce adaptive population differentiation among forest habitats. Thus, I. japonica populations formed local differentiation by adaptation of reproduction to local heterogeneous forest habitats.  相似文献   

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