Akustische Barrieren beim Waldbauml?ufer (Certhia familiaris)?

Zusammenfassung Waldbaumläufer besitzen je nach geographischer Herkunft deutlich verschiedene Reviergesangs-Strophen. Zusammenfassen lassen sich jene aus Mittel- und W-Europa (Certhia familiaris macrodactyla, mWb;C. f. britannica undC. f. corsa), aus dem weiteren Himalaya-Gebiet (Nepal,C. f. mandellii, nWb; und SW-China,C. f. khamensis, cwb) und als weitere Gruppe die aus Japan (C. f. orientalis, jWb). Differenzen im Gesang bestehen hinsichtlich der Zahl der Elemente in der Strophe, Frequenzumfang der Strophe, Frequenzverlauf der Elemente und deren Frequenzumfang. Der nWb reagiert nicht auf Gesang des mWb, umgekehrt besteht hohe Reaktionsfreudigkeit des mWb auf Str. des nWb. Freiland-Experimente mit unveränderten, gekürzten und künstlichen Str. aus gereihten Einzel-El. zeigen, daß bestimmter Frequenz-Verlauf der El. die Reaktion hervorruft. Es sind solche El. des nWb, die beim mWb in ähnlicher Form auftreten. Vielfach sind es aber El., die zwar vordergründig geringe oder keine Übereinstimmungen aufweisen, in einzelnen El.-Abschnitten jedoch erkennbare Frequenz-Entsprechungen besitzen. Einzelne dieser El. von mWb und nWb sind als homolog zu betrachten. In den meisten Fällen kann über die mögliche Homologie nicht entschieden werden, denn über El.-Veränderungen in der Evolution akustischer Signale ist bei Baumläufern zu wenig bekannt.

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Acoustic barriers in the Tree Creeper (Certhia familiaris)?

Summary Tree Creepers use according to their distributional origin different territorial songs. Populations with similar songs occur in Central and W Europe (C. f. macrodactyla, mWb;C. f. britannica, C. f. corsa), in Himalayan East Asia (Nepal,C. f. mandellii, nWb; SW China,C. f. khamensis, cWb) and Japan (C. f. orientalis, jWb). Differences in the territorial songs refer to number of elements in the verse, frequency volume of the verse, frequency modulation of the elements and their frequency volume. The Tree Creeper from Nepal (mandellii) does not react on the song of Central European Tree Creepers (macrodactyla), but the latter is very responsive tomandellii verses. Field experiments using unchanged, shortened or artificial verses consisting of one natural element arranged in a row, demonstrate that only certain frequency modulations evoke reactions. Such elements occur at least in similar expression in nWb and mWb as well. Often also such elements are answered which at first sight do not correspond or only to a low degree to mWb elements, but do so in certain small sections of mWb elements. Several of the similar elements in mWb and nWb are to be considered homologous. But in most cases where reaction in field experiments is high, the homology of the elements concerned cannot be substantiated. Changes of element structures in the course of vocal evolution in the [familiaris] superspecies is too poorly known.

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Results of the Himalaya Expeditions ofJ. Martens, No. 146. — For No. 145 see: Stuttgarter Beitr. Naturk., (A) 411: 1–43, 1987. — J. M. sponsored by Deutscher Akademischer Austauschdienst and Deutsche Forschungsgemeinschaft.     

The life-cycle of the asexual ostracod Darwinula stevensoni (Brady & Robertson, 1870) (Crustacea,Ostracoda) in a temporate pond

The life-cycle of the ancient asexual ostracod Darwinula stevensoni was studied during 1 year in a eutrophic pond in Belgium. The reproductive period of this species started in March and was effectively completed by September of the same year. All changes in population structure took place during the spring and summer months and a rapid turnover of the instars was observed. The life-cycle of Darwinula stevensoni appears to take one year or less in Belgium and this is considerably shorter than the 4 years which had been reported previously from subarctic populations. The difference to the present study is most likely temperature-related. Maximal densities of D. stevensoni were observed in June and July and attained 10⁵ ind. m^–2. During winter, densities were lower with a mean of 10⁴ ind. m^–2. Consequently, the calculated population size of each month was high throughout the year. Together with the low mutation rate, such a large population size could effectively counteract the stochastic loss of mutation-free genotypes as predicted by Muller's ratchet. D. stevensoni is a brooder; the maximum number of embryos and juvenile instars (up to third stage) found within a single female was 11.     

Tonnacypris glacialis (Ostracoda, Cyprididae): taxonomic position, (palaeo-) ecology, and zoogeography

Abstract. The freshwater ostracod Tonnacypris glacialis (Sars, 1890) is reported from the European Pleistocene for the first time. The historical allocation of the species is discussed, and the species composition and characteristics of Tonnacypris Diebel & Pietrzeniuk (1975) and its phylozoogeography are considered. The significance of T. glacialis is reviewed, particularly from the viewpoint of the possible implications of parthenogenesis (and occasional-male production) for the Quaternary history of the genus, and for the use of the species in palaeoenvironmental reconstruction. It is suggested that the Pleistocene fossil occurrence of T. glacialis in modern temperature latitudes is a robust indicator of mean summer temperatures of 6°C.     

Modeling the Interactions of Lactobacillus curvatus Colonies in Solid Medium: Consequences for Food Quality and Safety

The growth process of Lactobacillus curvatus colonies was quantified by a coupled growth and diffusion equation incorporating a volumetric rate of lactic acid production. Analytical solutions were compared to numerical ones, and both were able to predict the onset of interaction well. The derived analytical solution modeled the lactic acid concentration profile as a function of the diffusion coefficient, colony radius, and volumetric production rate. Interaction was assumed to occur when the volume-averaged specific growth rate of the cells in a colony was 90% of the initial maximum rate. Growth of L. curvatus in solid medium is dependent on the number of cells in a colony. In colonies with populations of fewer than 10⁵ cells, mass transfer limitation is not significant for the growth process. When the initial inoculation density is relatively high, colonies are not able to grow to these sizes and growth approaches that of broth cultures (negligible mass transfer limitation). In foods, which resemble the model solid system and in which the initial inoculation density is high, it will be appropriate to use predictive models of broth cultures to estimate growth. For a very low initial inoculation density, large colonies can develop that will start to deviate from growth in broth cultures, but only after large outgrowth.     

Expansion of Bacteriophages Is Linked to Aggravated Intestinal Inflammation and Colitis

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