Competing species often coexist, but the mechanisms allowing long-term coexistence are rarely tested via direct experimental manipulation. We experimentally tested the mechanisms of coexistence in a classic model system, laboratory microcosms in which two species of ciliate protists competed for bacteria. Previous work shows that the species used here compete for bacteria, but can coexist despite large differences in grazing ability. We tested three hypotheses that might explain this surprising coexistence: resource partitioning, chemically-mediated interference competition, and differential use of space. To test for resource partitioning, we conducted an experiment testing the effects of bacterial species richness and composition on the long-term outcome of competition. Manipulating bacterial diversity and composition alters the scope for resource partitioning. Despite strong evidence for differential resource use (e.g., the two ciliates shifted bacterial species composition in different ways), initial bacterial richness and composition did not affect the long-term outcome of competition. Remarkably, the competitive outcome was unchanged even when ciliates competed for a single bacterial species, indicating that the observed resource partitioning is irrelevant to the competitive outcome. In further experiments, we ruled out differential space use and chemically-mediated interference competition as explanations for this surprising coexistence. Coexistence of ciliates on a single bacterial species might reflect partitioning of intraspecific bacterial diversity, and/or osmotrophy or consumption of particulate detritus by the weaker competitor. The results show that this classic model system is not as well-understood as had been previously thought. More broadly, the results dramatically illustrate that merely observing “niche differences” between coexisting species is no evidence that those differences are either necessary or sufficient for long-term coexistence.
Authors:A. Qawasmeh, C. Bourke, S. Lee, M. Gray, W. Wheatley, N. J. Sucher, and A. Raman
Profiles of volatile secondary metabolites (VSM) in Mediterranean and Continental Festuca arundinacea, either endophyte free or infected with the fungal endophyte Neotyphodium coenophialum strain AR542, were determined using gas chromatography-mass spectrometry (GC-MS). The profile of VSM in the endophyte-free Mediterranean F. arundinacea germplasm was similar to that of endophyte-free Continental F. arundinacea germplasm. However, the VSM profile in AR542-infected Mediterranean F. arundinacea was different to that in AR542-infected Continental F. arundinacea. Compound 1, identified as N-acetylnorloline, was detected in AR542-infected Mediterranean F. arundinacea as being sevenfold greater compared with its level in AR542-infected Continental F. arundinacea. Levels of compounds 2, 4, and 5 detected in AR542-infected Mediterranean F. arundinacea were significantly lower when compared with their levels in the AR542-infected Continental F. arundinacea. Levels of compound 3 were similar in both germplasms infected with endophyte strain AR542. The levels of compounds 2, 4, and 5 but not compound 3 were different between AR542 infected and endophyte free depending on germplasm. On the basis of the mass spectra obtained, compounds 2, 3, 4, and 5 were identified as tridecanoic acid methyl ester, n-capric acid, 11, 14, 17-eicosatrienoic acid, and linoleic acid ethyl ester, respectively. Our results highlight key differences between the Mediterranean and Continental germplasms. Comparison of the VSM of AR542-infected Mediterranean F. arundinacea with AR542-infected Continental F. arundinacea showed that there are quantitative differences between the two germplasms. These differences, which may impact on grazing systems involving horses, most probably arose as a result of intrinsic genetic differences between the two germplasms and are yet to be indentified.
Changing countryside, society and culture. Contribution to the ethnology of the Bodrogköz region of NE Hungary in the 19th–20th centuries
. Bodrogköz is a historical region comprising some fifty settlements divided by the redrawing of the borders after the First World War: the northern part is now in the territory of Slovakia and the southern part in Hungary. The appearance of the countryside bordered by the Tisza, Bodrog and Latorca rivers was substantially changed by the deforestation and later, between 1845 and 1890, by the regulation of the rivers and flood control measures. The essay examines how the transformation of the landscape influenced the historical processes of peasant farming, the society and culture. Under its influence the earlier difference between the flood plains and the flood-free levels ceased to exist and there was a considerable overall increase in the proportion of ploughland. However, there was a marked decline in the area of grazing land that had provided the fodder for the earlier extensive livestock farming. With considerable differences between villages, the structure of peasant farms shifted towards keeping cattle in barns and in agriculture the role of fodder production greatly increased. The changes percolated through peasant society very slowly: a substantial part of the population continued to farm on infertile land. Many people sought prosperity in America and used the money earned there to buy land in their Bodrogköz settlements. The hierarchy of settlements in the region was also greatly altered by the transformation of the countryside. However, the region as a whole remained disadvantaged and the development of its society is still contradictory even today.
Authors:E. Chaideftou, A. Kallimanis, E. Bergmeier, and P. Dimopoulos
Over millions of years there is a long-term increase in species richness, accompanied by substantial turnover in species composition. However, little is known about species temporal turnover over shorter, ecologically relevant time periods, such as years. In the present study, we examine the inter-annual temporal turnover in species composition in 100 m2 plots of the herbaceous layer in a submediterranean oak woodland over six years. We found that approximately half of the accumulated number of species over the six years is accommodated as temporal turnover. We also found that species temporal turnover in undisturbed control plots was not significantly different from that in plots where vegetation was recovering naturally without assistance, i.e., plots undergoing ecological succession. Only in the most disturbed (continuously overgrazed) plots temporal turnover was low to non-existent. We therefore suggest that diversity estimates based on a single year of observations may seriously underestimate species richness or the detrimental effects of disturbance, at least at the 100 m2 scale. Furthermore, we found that, with the exception of the heavily grazed plots, short-lived species (annuals and biennials) did not display significantly greater temporal turnover than long-lived (perennial) species. Our analysis also supports that the space for time substitution applies in the patterns of species turnover. Spatial species turnover was comparable to temporal turnover. Species that are observed in many plots are also present in many years, and vice versa. Also, the similarity in species composition decreased as the time period between observations increased, as is the case with distance decay. Overall we conclude that the patterns of species turnover in time resemble those in space, and thus temporal turnover makes an important contribution to total biodiversity that should not be ignored.
Authors:Sándor Hoffmann, Gábor Csitári, László Bankó, and Júlianna Balázs
., Dexter, M., Perrott, K.W. (2003): Hot water extractable carbon in soils: a sensitive measurement for determining impacts of fertilization, grazing and cultivation. Soil Biol. Biochem., 35, 1231–1243.
. — Tsai J.: 2006a. Effect of different agronomical measures on yield and quality of autumn saved herbage during winter grazing 1
communication: Yield and digestibility of organic matter. Czech J. Anim. Sci. 51,5. 205–213 pp
Bread is baked from the crushed (or ground) seeds of grain. Around 10,000 years ago people cooked porridge or gruel and at least 3000 years ago leavened the dough of bread. In Europe, north of the Alps, it was only from the 16th century that the consumption of bread (and porridge) spread widely. Urban population concentrations grew, while yields fell due to the climatic deterioration. Greater areas of land were ploughed for grain cultivation and, independently of the quality of flour improved as a result of technical innovations in milling. The main factors for the dominance of grain were given. In regions where little was produced due to the natural endowments, such as the Mediterranean, bread grain was imported from Antiquity (Panem et circenses!). In mediaeval Europe nutrition was still characterised by the consumption of meat and vegetables (mainly cabbage). The balance tilted in the towns where the predominance of cereals can be observed. North-western Europe imported grain from the Baltic region. Up to the 18th century Eastern Central Europe exported beef cattle to the towns of Central Europe. As the demand for grain grew grazing land was ploughed and in the 19th century the country exported grain. Cereal consumption took the forms mainly of porridge, griddle-cakes, and later bread, dumplings and various kinds of boiled noodles. At the same time the role of soups (hot pots) in the daily diet increased. Bread and soup marked a new era in the history of menus. The people of Eastern Europe are still porridge-eaters. Almost from the start brewing has been one of the technologies for cereal consumption. Beer, with an increasing alcohol content, was at first the drink of urban dwellers, but later after the Middle Ages the peasantry also drank increasing quantities of ever stronger beer. Together with this latter process, grain spirits (whisky, gin, vodka, etc.) were also drunk on a growing scale. Distillation was an Arab invention and spread in the monasteries from the Middle Ages. At first Aqua vitae was a medicine but later shifted to the profane sphere in almost all respects.