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 46 毫秒
1.
《Journal of bryology》2013,35(3):469-478
Abstract

Leiocolea fitzgeraldiae sp. nov. from Wales, Scotland and Ireland is described and illustrated. Comparisons between it and the related species L. bantriensis and L. alpestris are outlined. Its cytology and habitat preferences are discussed and a distribution map is given.  相似文献   

2.
《Journal of bryology》2013,35(4):629-640
Abstract

New records of 38 hepatics and 87 mosses are reported from Greece. Leiocolea heterocolpos, Cephaloziella calyculata, Dicranella schreberiana, Hennediella stanfordensis, Weissia levieri, Grimmia alpestris and Grimmia torquata are believed to be new to the country. Claviform propagules formed by the excurrent nerve of the leaf are reported from a collection of Trichostomopsis australasiae.  相似文献   

3.
Abstract

Festuca alpestris R. et S. in the Alps near Belluno.—Some populations of Festuca from the F. varia aggr. occurring in the south-eastern Alps near Belluno have been recognized as belonging to F. alpestris R. et S. The relationships between this species and F. calva (Hackel) Richter from the Julian Alps are discussed and the diacritic characters are newly defined.  相似文献   

4.
Morphological and cytological investigations as well as crossing experiments were carried out withRanunculus seguieri Vill. and 4 species of theRanunculus alpestris L. group (R. alpestris L.,R. traunfellneri Hoppe,R. bilobus Bertol.,R. crenatus Waldst. & Kit.). ForR. seguieri andR. alpestris, localities and distribution are given in addition to extensive diagnoses. A key to the species includes morphological characteristics and distribution data forR. traunfellneri, R. bilobus, andR. crenatus. New diagnostic characters are described. Crossing experiments betweenR. seguieri and the species of theR. alpestris group were unsuccessful. All 5 species have a chromosome number of 2n = 16, the record forR. bilobus is new. There is no statistically significant difference between the karyotypes ofR. seguieri andR. alpestris s. str. Nevertheless, according to morphological evidence and crossing experiments,R. seguieri is not closely related to theR. alpestris group.
  相似文献   

5.
J. Dierschke 《Bird Study》2013,60(3):263-269
Capsule Seeds of plants from lower salt marsh communities are preferred, with insects less important.

Methods Droppings of Shorelarks Eremophila alpestris, Snow Buntings Plectrophenax nivalis and Twites Carduelis flavirostris sampled in the German Wadden Sea were analysed and compared with food abundance to assess preferences.

Results Shorelarks prefer seeds of Salicornia sp., Suaeda maritima, Atriplex sp., Halimione portulacoides and unidentified small grass seeds. Insects are eaten mainly in periods of seed shortage, but are consumed in smaller amounts during the winter. The food composition of Snow Buntings is very similar, but additionally Triglochin maritimum is commonly eaten. Twites are specialized on seeds of Salicornia sp. and Suaeda maritima and rarely ingest other seeds and insects. All seeds consumed were of plants from lower salt marsh communities. Many halophyte seeds, and especially those that birds feed on, are rich in energy. Large seeds and those which need a long handling time are avoided.

Conclusion Changes in the lower salt marshes of the Wadden Sea by embankments and intensified grazing might have been responsible for the rapid population decline from the 1960s to 1980s.  相似文献   

6.
Although many species have similar total distributional ranges, they might be restricted to very different habitats and might have different phylogeographical histories. In the European Alps, our excellent knowledge of the evolutionary history of silicate‐dwelling (silicicole) plants is contrasted by a virtual lack of data from limestone‐dwelling (calcicole) plants. These two categories exhibit fundamentally different distribution patterns within the Alps and are expected to differ strongly with respect to their glacial history. The calcicole Ranunculus alpestris group comprises three diploid species of alpine habitats. Ranunculus alpestris s. str. is distributed over the southern European mountain system, while R. bilobus and R. traunfellneri are southern Alpine narrow endemics. To explore their phylogenetic relationships and phylogeographical history, we investigated the correlation between information given by nuclear and chloroplast DNA data. Analyses of amplified fragment length polymorphism fingerprints and matK sequences gave incongruent results, indicative for reticulate evolution. Our data highlight historical episodes of range fragmentation and expansion, occasional long‐distance dispersal and on‐going gene flow as important processes shaping the genetic structure of the group. Genetic divergence, expressed as a rarity index (‘frequency‐down‐weighted marker values’) seems a better indicator of historical processes than patterns of genetic diversity, which rather mirror contemporary processes as connectivity of populations and population sizes. Three phylogeographical subgroups have been found within the R. alpestris group, neither following taxonomy nor geography. Genetic heterogeneity in the Southern Alps contrasts with Northern Alpine uniformity. The Carpathians have been stepwise‐colonised from the Eastern Alpine lineage, resulting in a marked diversity loss in the Southern Carpathians. The main divergence within the group, separating the ancestor of the two endemic species from R. alpestris s. str., predates the Quaternary. Therefore, range shifts produced by palaeoclimatic oscillations seem to have acted on the genetic structure of R. alpestris group on a more regional level, e.g. triggering an allopatric separation of R. traunfellneri from R. bilobus.  相似文献   

7.
Zusammenfassung Die Pulsationen der Lymphherzen von Normaltieren von Triturus vulgaris L. und T. alpestris Laur. sind unregelmäßig und verändern sich bei Erregung der Tiere. Die Lymphherzfrequenzen sind temperaturabhängig und folgen der R-G-T-Regel. Der Q 10 beträgt bei T. vulgaris 2,5, bei T. alpestris 2,1. In Narkose oder bei Spinaltieren sinkt die Lymphherzfrequenz gegenüber der von Normaltieren ab, der Rhythmus wird regelmäßig. Bei Spinaltieren tritt homolaterale Synchronie auf. Jedes Lymphherz hat ein eigenes motorisches Zentrum im Rückenmark; die Impulse werden über Spinalnerven geleitet. Die Ergebnisse werden mit den von Anuren bekannten verglichen.
Physiological investigations on the lymph hearts of urodelans
Summary The heart beats of normal individuals of Triturus vulgaris L. and T. alpestris Laur. are irregular and can be altered by excitation of the animal. The frequencies vary with alterations in temperature according to the rule of van t'Hoff. The Q 10 was measured as 2.5 for T. vulgaris and 2.1 for T. alpestris. In anesthetized and in spinal animals the frequencies are strongly reduced and the pulsations become regular. Spinal animals show homolateral synchrony of the lymph heart beats. The motor centres, separated for each lymph heart, are situated in the spinal cord; the impulses are mediated by spinal nerves. The results are compared with those of the Anurans.
  相似文献   

8.
Zusammenfassung Zur Prüfung der Fräge, ob der Blutkreislauf bei der Bestimmung der Asymmetrie der Nuclei habenulae des Zwischenhirns eine Rolle spielt, wurden Larven vonTriturus alpestris ohne Blutkreislauf durch Entfernung der Herzanlage hergestellt. Die Nuclei habenulae entwickelten auch ohne Kreislauf ihre normale Asymmetrie.Isolate aus dem Kopfbezirk der Neurula vonTriturus alpestris, die aus cephalem Ekto und Mesoderm bestanden und manchmal auch vorderes Entoderm enthielten, entwickelten in günstigen Fallen an ihrem Gehirn die Nuclei habenulae. Diese besaßen trotz Abwesenheit von Blutkreislauf und der anderen asymmetrischen Organe die normale Asymmetrie.
The development of asymmetrical nuclei habenulae in the diencephalon of amphibians, independent of blood circulation
Summary The problem whether the blood circulation influences or determines the asymmetry of Nuclei habenulae was tested by removing the heart-anlage of the embryo ofTriturus alpestris. The resulting larvae without any blood circulation developed their normal asymmetry of habenulae.Isolates from the head region of neurulae ofTriturus alpestris, consisting of cephalic ecto and mesoderm, sometimes also of entoderm, under favorable conditions could develop brains with Nuclei habenulae. These were normal, asymmetric in spite of missing the blood circulation and other asymmetrical organs.


Ausgefürhrt mit Unterstützung der Deutschen Forschugagemeinschaft.  相似文献   

9.
Morphological and cytological investigations as well as crossing experiments were carried out with the 5 species of theRanunculus alpestris group (R. alpestris L.,R. traunfellneri Hoppe,R. bilobus Bertol.,R. crenatus Waldst. etKit.,R. magellensis Ten.). A key to the species is presented; localities and distribution are given in addition to extensive diagnoses. Crossing experiments between the 5 taxa were successful (F1-F3 individuals, backcross types, tripeland quadrupelbastards); the morphology of the experimentally obtained F1-hybrids was mostly intermediate. All 5 species as well as all hybrids have a chromosome number of 2n = 16; there is no statistically significant difference between the karyotypes of the 5 taxa. According to the results of the morphological investigations and the crossing experiments we can distinguish 2 subunits of very closely related species: a)R. alpestris, R. traunfellneri, R. bilobus; b)R. crenatus, R. magellensis. The speciation within the group ofRanunculus alpestris is discussed.
  相似文献   

10.
11.
The skull of neotenic individuals of the Alpine Newt Triturus alpestris from the locality Drakolimni (Greece) is described on the basis of models made from magnified serial frontal sections. In order to recognize features associated with neoteny and paedomorphosis, the results were compared with normal development of contemporary Triturus and of other Caudata. The neotenic larvae from Greece correspond to advanced stages of metamorphosis in normal development of Triturus alpestris. Comparison with salamandrids from the Tertiary of Europe in which the hyobranchial skeleton was preserved, namely Brachycormus noachicus, Chelotriton paradoxus, and Palaeopleurodeles hauffi, revealed that both latter taxa were completely metamorphosed adults anatomically similar to their contemporary relatives Tylototriton, Echinotriton, and Pleurodeles, whereas Brachycormus, though apparently related to Chelotriton, was a neotenic amphibian. This is suggested by its incompletely metamorphosed but ossified hyobranchial skeleton. © 1996 Wiley-Liss, Inc.  相似文献   

12.
In this study, we applied geometric morphometrics to explore variations in the level and pattern of sexual size dimorphism (SSD) and sexual shape dimorphism (SShD) of the ventral cranium in three different Modern Eurasian newt taxa (Ichthyosaura alpestris, Triturus species group and Lissotriton vulgaris). The ventral cranium is the part of the skull that is more directly related to foraging and feeding. Our results indicate that the level and pattern of sexual dimorphism in the ventral cranium differ among Modern Eurasian newt taxa. Regarding sexual dimorphism in skull size, Ichthyosaura alpestris and Triturus species show female-biased patterns (females are larger than males), whereas Lissotriton vulgaris appears to be non-dimorphic in skull size. In I. alpestris and Triturus species, SShD is mostly absent, whereas in L. vulgaris, SShD is more pronounced. A high level of variation between populations in both SSD and SShD indicates that local conditions may have a profound effect on the magnitude and direction of sexual dimorphism. The significant sexual differences in ventral cranium size and shape indicate possible subtle intersexual differences in ecological demands due to diet specialisation, in spite of similar general ecological settings.  相似文献   

13.
Coexistence of species with similar requirements is allowed, among others, through trade‐offs between competitive ability and other ecological traits. Although interspecific competition is based on two mechanisms, exploitation of resources and physical interference, trade‐off studies largely consider only species’ ability to exploit resources. Using a mesocosm experiment, we examined the trade‐off between interference competition ability and susceptibility to predation in larvae of two newt species, Ichthyosaura alpestris and Lissotriton vulgaris. In the presence of heterospecifics, L. vulgaris larvae slowed somatic growth and developmental rates, and experienced a higher frequency of injuries than in conspecific environments which suggests asymmetrical interspecific interference. During short‐term predation trials, L. vulgaris larvae suffered higher mortality than I. alpestris. Larvae of the smaller species, L. vulgaris, had both lower interference and antipredator performance than the larger I. alpestris, which suggests a lack of trade‐off between interference competition ability and predator susceptibility. We conclude that interference competition may produce a positive rather than negative relationship with predation susceptibility, which may contribute to the elimination of subordinate species from common habitats.  相似文献   

14.
Morphological and karyological investigations as well as crossing experiments were carried out withR. cacuminis, R. crenatus, andR. alpestris. A key is presented including all 6 taxa of theR. alpestris-group. Ecological and geographical data for the Balkan Peninsula are also presented.R. cacuminis is diploid with 2n = 16 chromosomes as all taxa of the group, its karyotype exhibits no statistically significant differences to those from the 5 other taxa. In crossing experiments betweenR. cacuminis andR. alpestris, no hybrids could be obtained, whereas those betweenR. cacuminis andR. crenatus were slightly successful. According to its morphology, geographical distribution, and crossing behaviour,R. cacuminis is closely related toR. crenatus, and probably has originated fromR. crenatus by quantum speciation.  相似文献   

15.
Elsa L. Cabral 《Brittonia》2005,57(2):141-149
Four new species ofGalianthe (G. boliviana, G. chiquitosana, G. sudyungesis, andG. kempffiana) for Bolivia are described and illustrated.Galianthe kempffiana is also known from Brazil.Galianthe laxa andG. bisepala are reported for the first time for Bolivia.  相似文献   

16.
Abstract

Plant and lichen phytosociological studies describe the different dynamic stages of colonization. This approach has been applied to the Balangero asbestos mine, the most important of Western Europe up to 1990, which is a potential source for the air-dispersion of carcinogenic fibres. Vegetation relevés and maps have shown that plants and lichens develop spontaneously on the asbestos-rich substrates. Early colonization stages with low-covering hyperaccumulators, such as Thlaspi sylvium and Minuartia laricifolia, and with Thymus alpestris and T. cfr. humifusus, are followed, some decades later, by mature plant communities, which completely cover the asbestos-rich debris, thereby limiting the dispersion of fibres. Lichen colonization, even when limited to low covering early stages with pioneer crustose species, such as Scoliciosporum umbrinum and Candelariella vitellina, and young foliose thalli of Xanthoparmelia tinctina, is important whenever asbestos veins are exposed on serpentinite blocks and walls. Plants and lichens can be considered as bioattenuation (spontaneous bioremediation) agents in ecological recovery.  相似文献   

17.
The reproductive biology of the genusBaldellia was studied under cultivation and in nature.B. ranunculoides subsp.repens is self-incompatible whereasB. ranunculoides subsp.ranunculoides andB. alpestris are self-compatible. Bud-pollination occurs in theB. alpestris. Self-incompatibility correlates with the production of fewer, larger, more showy flowers, higher pollen production (but reduced pollen grain size), fewer carpels and smaller seeds. Resource allocation to sexual reproduction is inversely correlated with the degree of vegetative growth.B. ranunculoides subsp.repens produces more ramets than subsp.ranunculoides, which reproduces mainly by seeds.B. alpestris is intermediate between the two since it is self-compatible, produces fewer, larger seed than subsp.ranunculoides and is also able to propagate by vegetative means.  相似文献   

18.
19.
Five new species of Geonoma from Ecuador, G. awaensis, G. ecuadoriensis, G. hollinensis, G. lanata, and G. skovii, are described and illustrated and are compared to similar species. Their distributions are mapped.  相似文献   

20.
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