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1.
Ewald W. Roessler 《Hydrobiologia》1995,298(1-3):253-262
This paper presents an overview of the current knowledge about species diversity and morphological taxonomy of the Colombian conchostracan fauna. Relationships among morphological variability, reproduction biology and environmental conditions are stressed. The Colombian fauna includes 12 species in five families: Limnadiidae Sars, 1896; Leptestheriidae Daday, 1915; Cyclestheriidae G. O. Sars, 1899; Metalimnadiidae Strakraba, 1965; and Lynceidae Stebbing, 1902. No member of the families, Cyzicidae Stebbing, 1910, or Imnadiidae Botnariuc & Orghidan 1941 have been found in Columbia. Morphology depends on developmental stage and on the modulating effects of environmental conditions. Extremely high temperatures may lead to specimens with neotenic features inEulimnadia magdalenensis Roessler, 1990.  相似文献   

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Ohne ZusammenfassungHerrn Dr. D. Schneider danke ich für die Anregung des Themas und das stete Interesse an dem Verlauf der Arbeit, Herrn Prof. Dr. H. Autrum für die Überlassung eines Arbeitsplatzes im Zoologischen Institut.Dissertation der Naturwissenschaftlichen Fakultät der Universität München.  相似文献   

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Morphological changes during the process of ageing ofLeptestheria saetosa Marinek et Petrov, 1992 were observed. It was established thet the greatest number of analysed characteristics change intensively after sexual maturation. These changes continue throughout the entire life, although they are very slow in old specimens. Such a large number of changes brings about considerable morphological differences between adult specimens of different age.  相似文献   

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The genetic variability of the gonochoric Leptestheria dahalacensis (Rüppel, 1837) was studied through the analysis of mitochondrial and nuclear (microsatellite loci) markers in eight Italian and two Central European populations. Mitochondrial data exhibited a low variability, as only six mitotypes were scored: five in Italy and one for both Central European samples, with a very low number of substitutions. All analysed microsatellite loci were variable, with 3–5 alleles per locus and 1–4 alleles per population. All populations were at the Hardy–Weinberg equilibrium, with the exceptions of two samples for locus ldAC-16, due to heterozygote excess, and of four populations for locus ldAC-11, probably linked to the presence of null alleles. A substantial population structuring was found between Central European and Italian samples for both utilized markers. This observation may be explained by isolation by distance and/or recent isolation events. On the other hand, the absence of a clear inter-pond variability in Italian sample comparisons may be ascribed to high dispersal ability in the short range. Handling editor: K. Martens  相似文献   

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Graptolite faunas from theHolmograptus lentus,Pterograptus elegans, Hustedograptus teretiusculus andNemagraptus gracilis Zones are identified in the Ordovician succession of Rügen. The well sections bear incomplete, often fault-bounded successions. Tectonic stacking is present in the Rügen 3h core. A sedimentological gap is expected in the Arenig. About twenty graptolite species are described and their local biostratigraphic ranges are documented. Most of the faunal elements are described for the first time from the Ordovician of northern Germany. The faunal associations belong to the Atlantic Faunal Province.  相似文献   

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Ewald W. Roessler 《Hydrobiologia》1995,298(1-3):113-124
This study gives an overview and describes special aspects of the biology, ecology and the life cycle ofCyclestheria hislopi (Baird, 1859). This species is most commonly found in parthenogenically reproducing populations which produce large, directly developing nondiapause eggs. But periodically and under certain environmental conditions, sexually reproducing generations appear and produce diapause eggs. the sexual generations include males and particularly constituted females, which undergo a complete transformation into a special type of ephippium.Cyclestheria is the only known conchostracan species which does not occur in the initial phases of temporary water bodies, but develops in older temporary pools and even in permanent waters. It survives in the presence of effective depredators like fish by hiding within a special self-made mucus capsule.  相似文献   

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The gene products of 60 protein coding loci in Schilbe intermedius were examined by horizontal starch-gel electrophoresis. Electrophoretic analysis, using muscle and liver tissues, revealed polymorphism at 17 (28.3%) of the loci studied. The average heterozygosity (H) was calculated at 0.029 (±0.009) which is less than values obtained for other fish species. These results suggest that measures should be taken to conserve the genetic variation of this species.  相似文献   

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Ewald W. Roessler 《Hydrobiologia》1995,298(1-3):125-132
This study gives an overview of our current knowledge of the ecology and distribution patterns of Colombian conchostracans. Colombian euphyllopods are generally restricted to the warm tropical lowlands. OnlyCyclestheria hislopi can be found year-round in larger semipermanent waters and living sympatrically with abundant predators, such as planktivorous fish. The other conchostracans are restricted to the typical habitat of temporary waters.Eulimnadia magadalenensis is especially adapted to very short-term temporary ponds in relatively arid zones andE. colombiensis prefers somewhat cooler ponds of a longer duration. The two species can be found sympatrically in intermediate climatic conditions. A third form,Eulimnadia cf. geayi cohabits with the two other species in the lower Magdalena Valley, its ecological role is not clear.Limnadia orinoquiensis is the selvatic substitute of the open savannah conchostracan fauna (mainlyEulimnadia forms) living in pools in forest clearings in the vicinity of the Upper Orinoco.Four species of Lynceidae were found, twoLynceus and twoParalimnetis. Their distribution patterns are not yet clear, they prefer smaller temporary ponds of moderated temperatures. Two undescribed species ofLeptestheria were found, one restricted to the banks of the Orinoco and the other to one locality in the upper Magdalena Valley, living in ponds with a muddy bottom.Metalimnadia serratura was found in special rock pools of the Guiana Shield in the vicinity of the Orinoco, cohabiting with several other conchostracan species, with differential adaptations to very high water temperatures.  相似文献   

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Positional behavior (posture and locomotion), associated social/maintenance behaviors and selective utilization of available habitat structure were recorded for free-rangingColobus guereza occupying a remant montane forest near Limuru, Kenya. This research design focuses on relationships between anatomy, behavior, and the environment and provides a framework for interpreting adaptations inColobus. Quantitative analyses show daily activity patterns. These monkeys spend most of their time in above branch postural activities, primarily in sitting postures. Locomotion accounts for less than one-fifth of positional behavior. In both postural and locomotor sequences, the forelimbs may be placed above the shoulder complex, often in abducted positions. Suspensory positional behavior is rare. Most activity occurs within Zone II, flexible branches of medium diameter and less than 45° in grade. Selective use of the substrate and preferred positional modes are related to variables such as social/maintenance activities, weight distribution of the link system and substrate configuration. These data suggest that, (a) black and white colobus do not exhibit behavior associated with so-called “semibrachiation” and (b) bio-behavioral adaptations involving foraging and feeding strategies may account, in part, for observed morphological differences among Old World monkeys.  相似文献   

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Summary

Crustacea Tanaidacea collected by Prof. Dr. W. Noodt at the coasts of El Salvador and Peru. The species collected — Tanais stanfordi Richardson, Leptochelia savignyi (Kr?yer), Pseudo‐leptochelia filum (Stimpson), Heterotanais oerstedi (Kr?yer), and Teleotanais gerlachi Lang — are discussed. Some remarks are made concerning the Paratanaidae Lang. For Tanais stanfordi and Teleotanais gerlachi the differences with the known diagnoses are named. Both species are illustrated. Pseudoleptochelia filum is described and illustrated exactly. Except Leptochelia savignyi all species are new to the coasts of El Salvador and Peru.  相似文献   

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Summary The accuracy of orientation towards the source of concentric surface waves of 20 Hz or 60 Hz was measured in the back swimmerNotonecta glauca L. for varying angles of incidence a of the stimulus. The average absolute deviation of the insect's long axis from the goal after the first orienting turn increased from 2 ° at = 0 ° to 18 ° at = 180 °. The results are discussed with reference to the mechanisms involved in the localization of wave sources.

Mit Unterstützung der Deutschen Forschungsgemeinschaft (Ma 374/2; Ma 374/4 und 741,29).  相似文献   

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Zusammenfassung Die natürliche Strahleneinwirkung auf den menschlichen Atemtrakt wird im wesentlichen durch die Inhalation der kurzlebigen Zerfallsprodukte des Radons (Rn222) und Thorons (Rn220) verursacht. Ausgehend von der Größenverteilung des natürlich radioaktiven Aerosols und dem Landahlschen Lungenmodell wird die Abscheidung der Zerfallsprodukte in den einzelnen Regionen des Atemtrakts abgeschätzt. Die resultierende Aktivitätsverteilung wird unter Berücksichtigung des Ciliartransports und der Lungenausscheidung ermittelt. Die zugehörige Tiefendosisverteilung im Bronchialepithel wird angegeben, wobei die oc-Absorption in der Schleimschicht und die Abhängigkeit des-Bremsvermögens von der Energie berücksichtigt werden. Es zeigt sich, daß die natürliche Strahlenein Wirkung auf das Bronchialepithel erheblich höher sein dürfte, als auf Grund der bisherigen, stark vereinfachenden Abschätzungen angenommen wurde. Die maximale Dosisleistung ist im Bereich der mittleren Bronchien zu erwarten, wo mit einer mittleren natürlichen Belastung der Basalzellen von etwa 100 mrad/a bzw. 1 rem/a zu rechnen ist. Die Ergebnisse werden auch im Hinblick auf die Inhalation von Po210 beim Rauchen diskutiert.
Summary The natural radiation exposure of the human respiratory tract is mainly caused by the inhalation of the short-lived decay products of radon (Rn222) and thoron (Rn220). From the particle size distribution of the carrier aerosol of these decay products their deposition in different regions of the human respiratory tract and the resulting activity distribution is estimated for normal breathing conditions, taking into account the biological elimination from the alveolar region and the ciliar transport in the bronchial tree. The corresponding-depth dose distribution in the bronchial epithelium is derived, taking into account the-absorption and the variation of stopping power with-energy. The resulting natural radiation exposure of the bronchial epithelium is considerably higher than it was hitherto assumed. The maximum dose rate is reached in the segmental and subsegmental bronchi, where a mean natural radiation exposure of about 100 mrad/a or 1 rem/a must be expected in the basal cell layer. The results are discussed and compared with the RaF (Po210)-inhalation dose by cigarette smoking.


Erweitertes Manuskript eines Vortrags auf der Tagung der Deutschen Gesellschaft für Biophysik in Homburg/Saar vom 23. bis 24. April 1965.  相似文献   

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Summary The apical sensory cone on the antenna of a terrestrial isopod,Hemilepistus reaumuri, was investigated by both morphological and electrophysiological methods. It was found to consist of about 50 hair-like units, each containing 3–11 receptor cells which communicate with the environment through an apical porus. Single fiber recordings in the antennal nerve showed activity of receptor cells responding to mechanical, gustatory or olfactory stimuli. Two groups of olfactory and four groups of gustatory receptors were found.  相似文献   

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