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 312 毫秒
1.
The life form of G. conopsea (short-lived perennial with annual vegetative renewal) makes it possible to combine the long-term, complete ontogeny and polycarpy of the genet with the short life span and monocarpy of individual daughter ramets. Annual changes in the structural organization of daughter individuals allow the plants to adapt to changing environmental conditions and retain the territory they have occupied. Organismal mechanisms providing for the sustainable development of G. conopsea plants in marginal populations are considered in the context of the concept of multivariant plant ontogeny.  相似文献   

2.
Data are presented on the abundance, structure, and dynamics of hemipopulations of G. conopsea protocorms and autotrophic individuals at the northern boundary of the species range. The dynamics of ontogenetic structure of G. conopsea cenopopulations have a fluctuating pattern. Their response to adverse weather conditions is manifested in short-term reduction of density and increase in cenopopulation ageness in subsequent years. Deterioration of growing conditions in a series of ecotopes is accompanied by an increase in the proportion of young individuals, which allows the species to level off the impact of adverse weather factors on population size.  相似文献   

3.
Morphological trait variation in populations of rhizomatous (Cypripedium calceolus, Listera ovata) and root-tuber orchid species (Platanthera bifolia, Gymnadenia conopsea) has been studied along a latitudinal gradient in Europe. It has been shown that the structure of shoots changes with transition from the center to the northern or southern periphery of the species range. The reduction in the number of metameres at the range periphery is more distinct in orchids with multimetameric shoots, compared to those with oligometameric shoots. The plasticity of shoot structure observed along the geographic gradient is contingent on climatic factors and can be manifested regionally in cases of long-term temperature deviations. Other morphological parameters, such as shoot height and the sizes of leaves and flowers, can serve as indicators of ecological conditions in habitats.  相似文献   

4.
Multivariate analysis of variation in the metric characters in the ground beetle C. granulatus has been performed. It has been shown that the beetle body size increases toward the center of its range, urbanization has a positive effect on all metric traits, but the effect of habitat vegetation has no definite trend. The structure of variation in the metric characters estimated by the principal components method depends on all ecological factors considered: the locality in the geographic range, level of anthropogenic influence, and degree of biotope openness.  相似文献   

5.
Analysis of variation in morphological characters of Potanin Altai osman, Oreoleuciscus potanini, from two freshwater and one brackish water lakes of Western Mongolia has shown that specimens of different ecological forms—herbivorous and piscivorous—form two integral and, at the level under consideration, internally indivisible units in the system of phenetic diversity of the species O. potanini.  相似文献   

6.
Top predators in northern ecosystems may suffer from exposure to persistent organic pollutants (POPs) as this exposure may synergistically interact with already elevated natural stress in these ecosystems. In the present study, we aimed at identifying biological (sex, body condition), ecological (dietary carbon source, trophic level) and spatial factors (local habitat, regional nest location) that may influence intra- and interspecific variation in exposure of subarctic predatory bird nestlings to polychlorinated biphenyl 153 (CB 153), polybrominated diphenyl ether 47 (BDE 47), dichlorodiphenyldichloroethylene (p,p′-DDE) and hexachlorobenzene (HCB). During three breeding seasons (2008–2010), we sampled body feathers from fully-grown nestlings of three ecologically distinct predatory bird species in subarctic Norway: Northern Goshawk (Accipiter gentilis), White-tailed Eagle (Haliaeetus albicilla) and Golden Eagle (Aquila chrysaetos). The present study analysed, for the first time, body feathers for both POPs and carbon (δ13C) and nitrogen (δ15N) stable isotopes, thus integrating the dietary carbon source, trophic level and POP exposure for the larger part of the nestling stage.Intraspecific variation in exposure was driven by a combination of ecological and spatial factors, often different for individual compounds. In addition, combinations for individual compounds differed among species. Trophic level and local habitat were the predominant predictors for CB 153, p,p′-DDE and BDE 47, indicating their biomagnification and decreasing levels according to coast > fjord > inland. Variation in exposure may also have been driven by inter-annual variation arisen from primary sources (e.g. p,p′-DDE) and/or possible revolatilisation from secondary sources (e.g. HCB). Interspecific differences in POP exposure were best explained by a combination of trophic level (biomagnification), dietary carbon source (food chain discrimination) and regional nest location (historical POP contamination).In conclusion, the combined analysis of POPs and stable isotopes in body feathers from fully-grown nestlings has identified ecological and spatial factors that may drive POP exposure over the larger part of the nestling stage. This methodological approach further promotes the promising use of nestling predatory bird body feathers as a non-destructive sampling strategy to integrate various toxicological and ecological proxies.  相似文献   

7.
Geometric morphometrics has been used to reveal coupled geographic variation in the mandible shape in two sympatric rodent species, the pygmy wood mouse (Sylvaemus uralensis Pall.) and bank vole (Myodes glareolus Pall.), in the Southern Urals. It has been shown that syntopic samples synchronously collected from the local communities of these species usually display similar, parallel, and unidirectional morphological changes as demonstrated by comparison of species pairs from different localities. The degree of concordance in geographic variation of the species makes it possible to estimate their coevolutionary potential within local communities: the wider the range of ecological conditions under which parallel variation of sympatric species is observed, the higher is their coevolutionary potential.  相似文献   

8.
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   

9.
Ecological and biological characteristics of Cyclachaena xanthiifolia (Nutt.) Fresen., have been studied in four regions of the Southern Urals and Cisural region. Communities including this species have been attributed to association Ivetum xanthiifoliae Fija?kowski 1967 of the class Stellarietea mediae R.Tx., Lohmeyer et Preising 1950. It has been shown that ecological habitat conditions have a significant effect on the majority of morphometric parameters of C. xanthiifolia, accounting for 1.3 to 51.4% of their total variance. Seed production averages 6500 seeds per plant. Extensive dispersal of the species over the Southern Ural region is predicted.  相似文献   

10.
Heterogeneity of precipitation could influence various physiological and ecological processes of plants. We present a comparative study on the ecophysiological responses of two congenerous species, Mosla chinensis (an endemic species) and M. scabra (a weedy species), to four soil water content (20%, 40%, 60% and 90% of water holding capacity (WHC), referred to as W20, W40, W60 and W90, respectively) to understand their ecophysiological responses and ecological differentiation. Results showed that both species grew well from W40 to W90, as they showed higher photosynthetic rate and biomass and bigger plants under these soil water content. However, biomass, chlorophyll a to b ratio (Chl a/b) and root to shoot ratio (R/S) of M. scabra but not M. chinensis were significantly reduced under W20, indicating M. chinensis showed stronger capacity of sun-acclimation under severe drought than M. scabra. M. chinensis showed priority in adapting severe drought in comparison with M. scabra. We hypothesize that the different adaptive abilities to soil water content are partly responsible for their ecological differentiation observed in the field and may affect their fate in their native habitat.  相似文献   

11.
Analysis of geographic variation of chloroplast DNA in the eastern European and western Siberian (Tobol) groups of Calluna vulgaris populations isolated from each other for a long period of time has revealed distinct differentiation between them. It has been shown that three populations growing in the Russian Plain and Karelia share two haplotypes characteristic of central Europe, while three Tobol populations contain one haplotype F occurring in Sweden. These results confirm the hypothesis of genetic divergence between the Tobol and eastern European groups of C. vulgaris populations.  相似文献   

12.
Glaucium flavum Crantz. is a short-lived perennial herb distributed in coastal zones from the Black Sea to southern, western and north-western Europe. Despite its diminishing area of distribution and potential pharmacological value, little is known about the ecophysiological features of this coastal species. We investigated the photosynthetic performance of G. flavum by measuring gas exchange, chlorophyll fluorescence, photosynthetic pigment concentration and leaf water content over the space of a year in a coastal habitat of SW Spain. We also measured the variation in total concentrations of nitrogen, phosphorus, sulphur, potassium, calcium and magnesium, in the leaves and soil, throughout the study period. G. flavum showed a high resistance to summer drought conditions which appeared to be due to the high degree of stomatal control. The potential photochemical efficiency of photosystem II showed minimum values during the winter, indicating that low temperatures can produce negative effects within the photosynthetic apparatus. However, the marked decline in net photosynthesis during the winter seems to be mainly related to a loss of metabolic activity. Although leaf nutrient concentrations were, in general, within the normal ranges, phosphorus availability seems to be limited by the high calcium concentrations detected in the soil of the study site. Our study points out the efficiency of the different physiological adaptations of this rare and endangered coastal species in coping with the strong seasonal variability of the Mediterranean climate.  相似文献   

13.
The genus Oenanthe comprises approximately 22 species, of which 16 species are restricted to the desert belt of the Palaearctic and Afrotropic regions, where they are often the most conspicuous passerines. Although they have been the subjects of some morphological and ecological studies, no complete morphometrical data has been used to verify their taxonomic relationships, and, the species relationships are still debated. Overall morphometrical similarities between Wheatears and their relationships in size and shape were assessed using measurements of 27 biometrical variables on 417 museum specimens. The 22 Wheatear species comprise some morphological groups: long migratory vegetation-tolerant species (O. pleschanka, O. hispanica, O. cypriaca and O. deserti), ground-dwelling migratory (O. isabellina and O. oenanthe), and sedentary (O. bottae, O. heuglini and O. pileata) of steppe-like habitants, relatively heavy and rock-dwelling species (O. leucura and O. monticola), inhabiting the most arid areas (O. monacha, O. leucopyga and O. alboniger), and finally a central core of medium-sized partial migrants, largely overlapping in morphometric space, that do not present any evident specialization (O. lugens, O. chrysopygia, O. xanthoprymna and O. finschii). It seems Wheatear species are well distributed in a morpho-space of size and shape with moderate overlaps and few hiatuses corresponding to a morphological continuum of species. Furthermore, our results largely hiatuses corresponding to a morphological continuum of species. Furthermore, our results largely differ from previous phylogenetic hypotheses (based on ecological, behavioural, and chromatic characters), but, are in congruence with molecular data.  相似文献   

14.
Data are presented on the geographic distribution, habitat, phytocenotic preferences, morphology, ecological features, and demographic parameters of V. tsydenii, a rare species in Russia. Measures are proposed to protect its local habitat.  相似文献   

15.
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   

16.
Molecular genetic methods (AFLP and ITS1–5.8S–ITS2 rDNA analysis) have been used to study the level and structure of genetic diversity in relict populations of the Ural endemic Gypsophila uralensis Less. in the northeast of European Russia. Intraspecific genetic differentiation is most clearly manifested between G. uralensis Less. subsp. pinegensis (Perf.) Kamelin locally endemic to the north of Europe (Arkhangelsk oblast, locus classicus) the population of G. uralensis Less. subsp. uralensis on limestone outcrops along the Shchugor River, the Subpolar Urals. The cluster of Timan populations (on limestone outcrops along the Svetlaya, Pizhma, and Myla rivers) is autonomous and genetically heterogeneous. Genetic distances between model G. uralensis s.l. populations are correlated with geographic distances. The size and abundance of relict populations show a descending gradient in the forest zone, and parameters of their genetic diversity [1] and unbiased expected heterozygosity have been found to decrease along this gradient.  相似文献   

17.
An trench profile method was used to study seasonal variation of root ecological characteristics of Alhagi sparsifolia Shap. seedlings under different irrigation treatments. The results indicated the following: (1) Root morphology: under excellent soil moisture conditions, A. sparsifolia seedlings developed many horizontal roots and root sprouts to compete for light; but under poor soil moisture, the vertical root system expanded its resource space into deeper soil. Plasticity of root morphology is an important strategy to capture water and adapt to the hyperarid environment. (2) Root/shoot ratio: root/shoot ratio increased with declining soil moisture, and this trend was more obvious later in the growing season. Increase of root/shoot ratio is a strategy for adapting to drought. (3) Growth of root system: The seedlings prefer to develop roots in shallower surface layers with less water availability. The growth depth and vertical growth rate of roots increased with decreased soil moisture. (4) Accumulation of root biomass: biomass and surface area of the root system decreased with increased soil depth, with the roots distributed in an ??inverted pyramid?? in vertical section view. The formation of root biomass conformed to a logistic ??slow-quick-slow?? growth curve, and total biomass decreased with intensity of soil drought. The findings will provide data useful for effective restoration of A. sparsifolia and better utilization of water resources in hyperarid regions.  相似文献   

18.
The causes and ecological consequences of alien plant species invasions in the Southern Urals are analyzed. Aggressive invasive species of North American origin??Ambrosia trifida L., A. psylostachya DC., Cyclachaena xanthiifolia (Nutt.) Fresen., Hordeum jubatum L., Oenothera biennis L., Bidens frondosa L., etc.??have invaded synanthropic and natural plant communities and became dominant, with their proportion varying from 10 to 99%. The biomass of these plants may reach 6 kg/m2; density, more than 1000 shoots per square meter; and seed production, up to 30000 seeds per plant, which explains their dominance in communities. The ecological hazard they pose lies in the displacement of native species, overgrowing of disturbed land areas, and allergenicity of their pollen.  相似文献   

19.
Lantana camara. L (hereafter Lantana) was first introduced by the British into India in 1807 as an ornamental plant. Since then the species has spread across the length and breadth of the country. Attempts to control Lantana in India have not been successful. In this study, we analysed the use of Lantana by local communities in southern India and identified the possible causes and consequences of its use through the use of a household survey of the socio-economic profile of the user and nonuser households and an analysis of the ecological history of the communities. Communities have been using Lantana for over 25–30 years and apparently such use was not prompted by external agencies. The characteristics of user and nonuser households were similar, except that Lantana users were more literate and had a greater number of occupations per household than nonusers. Per capita income was similar between user and nonuser groups. For nonuser groups, their main income sources were from trading (44 %), wage labour (32 %) and forest resources (23 %). In contrast, the Lantana user groups substituted their loss of income from forest resources (7 %) by income from Lantana (46 %). The ecological history revealed that Lantana was adopted as a resource at a time when it was increasing in the landscape and traditional bamboo resources were in decline because of overuse by commercial enterprises and mast flowering. This change in ecological resource availability prompted a major shift in livelihoods for some in the area.  相似文献   

20.
Indian pangolin (Manis crassicaudata) is a fossorial, “Near threatened” mammalian species occurring in Pakistan and facing a risk of endangerment in its wild habitat. Being nocturnal, ecological data of the species is lacking in the country and in south Asia as well. The current study investigated some ecological parameters of the species like, distribution, habitat analysis, population and food habits in district Chakwal of Potohar Plateau. Illegal trapping and killing by professional nomads for its scales is the main threat to the species in the study area.  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