281 research outputs found
Restrukturierungsprozesse einer Stadt-Umland Ökonomie : Veränderung der Wirtschaftsstruktur im Agglomerationsraum Basel
No full textGlobalization trends lead to economic processes of
restructuring in the City of Basle and its surrounding
area. Characteristics of this development are: loss of Jobs, increasing unemployment, sectoral restructuring and flexible forms of production and employment.Tendencies towards a spatial concentration or deconcentration of certain economic branches that can be observed on a global scale, can only be found to a smaller degree in the economic
region of Basle. Distinctive regional features and Basle's position in the national city-system modify this development.The restructuring processes have different effects on the city and the suburban zone. Within the surrounding areas there is no homogenous development. Therefore, it is necessary to maximize the existing opportunities and to implement equalizing mechanisms that secure the competitiveness of the region as a whole
THE SPARTAN SCHOOL OF INSTITUTIONAL ECONOMICS AT MICHIGAN STATE UNIVERSITY
No full textHeterodox scholarship at Michigan State University (MSU) was influenced by the institutional economics of John R. Commons at Wisconsin. But it was far from monolithic and had many other sources and originality of its own. A case can be made that the center of institutional economics moved across Lake Michigan from Madison to East Lansing and blossomed in the second half of the 20th century with such Wisconsin Ph.D's as Raleigh Barlowe, Warren Samuels, Allan Schmid, Harry Trebing, and others. Equally important in making MSU a center of institutional economics were scholars from other institutional backgrounds such as Paul Strassmann, economic development; Robert Solo, science and technology; James Shaffer, agricultural marketing and consumer behavior; Nicholas Mercuro, law and economics; and others.Institutional and Behavioral Economics,
The costs and benefits of being a chimera
No full textMost multicellular organisms are uniclonal. This is hypothesized to be because uniclonal organisms function better than chimeras (non-clonal organisms), owing to reduced levels of internal genetic conflict. We tested this idea using the social amoeba or slime mold Dictyostelium discoideum. When starving, the normally solitary amoebae aggregate to form a differentiated multicellular slug that migrates towards light and forms a fruiting body, facilitating the dispersal of spores. We added 107 amoebae to Petri plates containing 1, 2, 5 or 10 clones mixed together. We found an intrinsic cost to chimerism: chimeric slugs moved significantly less far than uniclonal slugs of the same size. However, in nature, joining with other clones to form a chimera should increase slug size, and larger slugs travel further. We incorporated this size effect into a second experiment by giving chimeras more cells than single clones (single clones had 106 cells, two-clone chimeras had 2 x 106 cells and so on). The uniclonal treatments then simulated a clone in a mixture that refuses to form chimeras. In this experiment, chimeras moved significantly further than the uniclonal slugs, in spite of the intrinsic cost. Thus, chimerism is costly, which may be why it evolves so seldom, but in D. discoideum the benefits of large size appear to compensate
The cost of queen loss in the social wasp Polistes dominulus (Hymenoptera: Verpidae)
No full textLoss of the queen is a crisis for a social insect colony. The process of queen succession could cause increased aggression and work inefficiencies, and the new queen, if the colony can produce one, could be slow to develop mature eggs. We evaluated the cost of queen replacement in Polistes dominulus by removing the queen from a set of single-foundress colonies while leaving a control set with their queens. At 2 and 11 days after queen removal, we found that the queenless colonies had increased levels of some dominance behaviors, chewing and climbing, but not of the far more common lunging and biting. However, foraging behavior did not decrease on nests without queens as compared to nests with their original queens. Nest growth diminished as compared to control nests, as would be expected if new queens were not as competent at egg laying or if dominance behavior interfered with nurturing activities. Furthermore, replacement queens did not mate in the first 12 days after queen removal and few had mature eggs in their ovaries, though after a month most had mated and had developed ovaries. The degree of ovarian dominance of the top egg-layer over the others was also diminished at 12 days, but by a month the new queen was as dominant as control queens. The high cost of replacing the queen may indicate that workers are kept reproductively suppressed enough not to be a threat to the existing queen. © 2004 Kansas Entomological Society
Microsatellite genotyping of apple (Malus × domestica Borkh.) genetic resources in the Netherlands: application in collection management and variety identification
No full textA highly informative set of 16 microsatellite markers was used to fingerprint 695 apple accessions from eight Dutch collections. Among the total sample, 475 different genotypes were distinguished based on multi-locus microsatellite variation, revealing a potential redundancy within the total sample of 32%. The majority of redundancies were found between collections, rather than within collections. No single collection covered the total observed diversity well, as each collection consisted of about 50% of unique accessions. These findings reflected the fact that most collection holders focus on common Dutch varieties, as well as on region-specific diversity. Based on the diversity patterns observed, maintenance of genetic resources by a network of co-operating collection holders, rather than by collecting the total diversity in a single collection appears to be an efficient approach. Comparison of microsatellite and passport data showed that for many accessions the marker data did not provide support for the registered variety names. Verification of accessions showed that discrepancies between passport and molecular data were largely due to documentation and phenotypic determination errors. With the help of the marker data the varietal names of 45 accessions could be corrected. Microsatellite genotyping of apple appears to be an efficient tool in the management of collections and in variety identification. The development of a marker database was considered relevant as a reference instrument in variety identification and as a source of information about thus far unexplored diversity that could be of interest in the development of new apple varietie
Genetic Relatedness and Population Structure in Primitively Eusocial Wasps in the Genus Mischocyttarus (Hymenoptera: Vespidae) David C Queller, Joan E Strassmann, and Colin R Hughes
No full textVolume: 1Start Page: 81End Page: 8
Contrasting patterns of Y chromosome and mtDNA variation in Africa: Evidence for sex-biased demographic processes
No full textTo investigate associations between genetic, linguistic, and geographic variation in Africa, we type 50 Y chromosome SNPs in 1122 individuals from 40 populations representing African geographic and linguistic diversity. We compare these patterns of variation with those that emerge from a similar analysis of published mtDNA HVS1 sequences from 1918 individuals from 39 African populations. For the Y chromosome, Mantel tests reveal a strong partial correlation between genetic and linguistic distances (r=0.33, P=0.001) and no correlation between genetic and geographic distances (r=-0.08, P>0.10). In contrast, mtDNA variation is weakly correlated with both language (r=0.16, P=0.046) and geography (r=0.17, P=0.035). AMOVA indicates that the amount of paternal among-group variation is much higher when populations are grouped by linguistics (Phi(CT)=0.21) than by geography (Phi(CT)=0.06). Levels of maternal genetic among-group variation are low for both linguistics and geography (Phi(CT)=0.03 and 0.04, respectively). When Bantu speakers are removed from these analyses, the correlation with linguistic variation disappears for the Y chromosome and strengthens for mtDNA. These data suggest that patterns of differentiation and gene flow in Africa have differed for men and women in the recent evolutionary past. We infer that sex-biased rates of admixture and/or language borrowing between expanding Bantu farmers and local hunter-gatherers played an important role in influencing patterns of genetic variation during the spread of African agriculture in the last 4000 years
Genotypic diversity and population structure in Dictyostelium discoideum
No full textCurrent population genetics literature presumes a lack of population structure in microorganisms due to their large population sizes, ubiquitous dispersal, and absence of geographic barriers. Contrary to this, we found evidence of great population subdivision in the social amoeba, Dictyostelium discoideum. Pairwise values of Fst and Rst were significant between samples collected from sites separated by distances from 100m--10,000km (P < 0.05 after sequential Bonferroni). Three- and two-level analyses of molecular variance (AMOVA) confirmed the existence of population structure (Fst 0.30, Rst = 0.48, P < 0.001 for three-level; Fst = 0.297, Rst = 0.474, P < 0.001 for two-level). Further, linearized pairwise Fst values were significantly correlated with natural logarithm of geographic distance (r = 0.471, P < 0.012) indicating isolation by distance. Genotypic diversity of populations remained moderate (Nei (1987) average gene diversity ∼0.50) in spite of the decreased population diversity expected with such Fst and Rst values
Mechanisms of cheating behavior in the social amoeba Dictyostelium discoideum
No full textDictyostelium discoideum is a eukaryotic micro-organism with a unique life cycle. The amoebae live as haploid, free-living cells in the soil feeding on bacteria and dividing asexually. Under starvation conditions, the cells aggregate and undergo a process of differentiation into spores and stalk cells. We speculate that the stalk cells are sacrificed to help raise the spores above the substrate and to improve their dispersal and survival. In the case of a mix between two or more genetically different clones, a conflict may arise over which cells become spores and survive and which become stalk and die. One that differentiates more spores than its fair share in chimera is called a "cheater" and the other a "loser". Dictyostelium discoideum is a useful organism for studying the complexity of social behavior in microorganisms. Molecular tools have been developed allowing the study of genetic mechanisms that underlie this social behavior.
To investigate the molecular basis of cooperation, several pools of knock-out mutants were generated using the REMI (R&barbelow;estriction E&barbelow;nzyme M&barbelow;ediated I&barbelow;ntegration) technique. To simulate evolutionary selection for cheaters, the different mutants were subjected to rounds of spore germination, growth and development in a mixed population. Only the spores were taken to the next generation. Real Time PCR confirmed that cheaters became over-represented in the evolving population because they contribute spores with a higher efficiency than the other mutants. Mutants expressing a normal phenotype were picked and isolated after 10 and 20 cycles of selection and mixed in pairwise experiments with the parental wild type. At least 35 mutants have been tested and 29 were cheaters. Analysis of the isolated genes suggested that several genetic pathways are involved in regulating or modulating the complex cooperation process in Dictyostelium discoideum.
Finally we characterized one cheater mutant, called chtB, which shows apparently normal phenotype when plated clonally. The mutant is lacking in the expression of the gene chtB. In chimeras, this causes the reduction of the expression of the prespore marker cotB in the wild type strain, enabling the cheater to differentiate more spores than the parental strain
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