Production flexibility, product markets, and capital structure decisions

We examine how production flexibility affects financial leverage. A worldwide sample of energy utilities allows us to apply direct measures for production flexibility based on their power plants. We find that production flexibility increases financial leverage. For identification, we exploit privatizations and deregulations of electricity markets, geographical variations in natural resources, the technological evolution of gas-fired power plants, and differences in electricity prices and recapitalization cost across regions. Production flexibility affects financial leverage via the channels of reduced expected cost of financial distress and higher present value of tax shields. The relative importance of these channels depends on firms' profitability.postprin

No Evolutionary Shift in the Mating System of North American Ambrosia artemisiifolia (Asteraceae) Following Its Introduction to China

The mating system plays a key role during the process of plant invasion. Contemporary evolution of uniparental reproduction (selfing or asexuality) can relieve the challenges of mate limitation in colonizing populations by providing reproductive assurance. Here we examined aspects of the genetics of colonization in Ambrosia artemisiifolia, a North American native that is invasive in China. This species has been found to possess a strong self-incompatibility system and have high outcrossing rates in North America and we examined whether there has been an evolutionary shift towards the dependence on selfing in the introduced range. Specifically, we estimated outcrossing rates in one native and five invasive populations and compared levels of genetic diversity between North America and China. Based on six microsatellite loci we found that, like the native North American population, all five Chinese populations possessed a completely outcrossing mating system. The estimates of paternity correlations were low, ranging from 0.028–0.122, which suggests that populations possessed ∼8–36 pollen donor parents contributing to each maternal plant in the invasive populations. High levels of genetic diversity for both native and invasive populations were found with the unbiased estimate of gene diversity ranging from 0.262–0.289 for both geographic ranges based on AFLP markers. Our results demonstrate that there has been no evolutionary shift from outcrossing to selfing during A. artemisiifolia's invasion of China. Furthermore, high levels of genetic variation in North America and China indicate that there has been no erosion of genetic variance due to a bottleneck during the introduction process. We suggest that the successful invasion of A. artemisiifolia into Asia was facilitated by repeated introductions from multiple source populations in the native range creating a diverse gene pool within Chinese populations

Allogamy-Autogamy Switch Enhance Assortative Mating in the Allotetraploid Centaurea seridis L. Coexisting with the Diploid Centaurea aspera L. and Triggers the Asymmetrical Formation of Triploid Hybrids

[EN] Hybridization between tetraploids and its related diploids is generally unsuccessful in Centaurea, hence natural formation of triploid hybrids is rare. In contrast, the diploid Centaurea aspera and the allotetraploid C. seridis coexist in several contact zones where a high frequency of triploid hybrids is found. We analyzed the floral biology of the three taxa to identify reproductive isolation mechanisms that allow their coexistence. Flowering phenology was recorded, and controlled pollinations within and between the three taxa were performed in the field. Ploidy level and germination of progeny were also assessed. There was a 50% flowering overlap which indicated a phenological shift. Diploids were strictly allogamous and did not display mentor effects, while tetraploids were found to be highly autogamous. This breakdown of self-incompatibility by polyploids is first described in Centaurea. The asymmetrical formation of the hybrid was also found: all the triploid intact cypselae came from the diploid mothers pollinated by the pollen of tetraploids. Pollen and eggs from triploids were totally sterile, acting as a strong triploid block. These prezygotic isolation mechanisms ensured higher assortative mating in tetraploids than in diploids, improving its persistence in the contact zones. However these mechanisms can also be the cause of the low genetic diversity and high genetic structure observed in C. seridis.Ferriol Molina, M.; Garmendia, A.; Ana Gonzalez; Merle Farinós, HB. (2015). Allogamy-Autogamy Switch Enhance Assortative Mating in the Allotetraploid Centaurea seridis L. Coexisting with the Diploid Centaurea aspera L. and Triggers the Asymmetrical Formation of Triploid Hybrids. PLoS ONE. 10(10):1-13. doi:10.1371/journal.pone.0140465S1131010Jiao, Y., Wickett, N. J., Ayyampalayam, S., Chanderbali, A. S., Landherr, L., Ralph, P. E., … dePamphilis, C. W. (2011). Ancestral polyploidy in seed plants and angiosperms. Nature, 473(7345), 97-100. doi:10.1038/nature09916Wood, T. E., Takebayashi, N., Barker, M. S., Mayrose, I., Greenspoon, P. B., & Rieseberg, L. H. (2009). The frequency of polyploid speciation in vascular plants. Proceedings of the National Academy of Sciences, 106(33), 13875-13879. doi:10.1073/pnas.0811575106ROMASCHENKO, K., ERTUǦRUL, K., SUSANNA, A., GARCIA-JACAS, N., UYSAL, T., & ARSLAN, E. (2004). New chromosome counts in the Centaurea Jacea group (Asteraceae, Cardueae) and some related taxa. Botanical Journal of the Linnean Society, 145(3), 345-352. doi:10.1111/j.1095-8339.2004.00292.xHardy, O. J., de Loose, M., Vekemans, X., & Meerts, P. (2001). Allozyme segregation and inter-cytotype reproductive barriers in the polyploid complex Centaurea jacea. Heredity, 87(2), 136-145. doi:10.1046/j.1365-2540.2001.00862.xKOUTECKÝ, P., BAĎUROVÁ, T., ŠTECH, M., KOŠNAR, J., & KARÁSEK, J. (2011). Hybridization between diploidCentaurea pseudophrygiaand tetraploidC. jacea(Asteraceae): the role of mixed pollination, unreduced gametes, and mentor effects. Biological Journal of the Linnean Society, 104(1), 93-106. doi:10.1111/j.1095-8312.2011.01707.xKoutecký, P. (2012). A diploid drop in the tetraploid ocean: hybridization and long-term survival of a singular population of Centaurea weldeniana Rchb. (Asteraceae), a taxon new to Austria. Plant Systematics and Evolution, 298(7), 1349-1360. doi:10.1007/s00606-012-0641-5Mráz, P., Španiel, S., Keller, A., Bowmann, G., Farkas, A., Šingliarová, B., … Müller-Schärer, H. (2012). Anthropogenic disturbance as a driver of microspatial and microhabitat segregation of cytotypes of Centaurea stoebe and cytotype interactions in secondary contact zones. Annals of Botany, 110(3), 615-627. doi:10.1093/aob/mcs120Olšavská, K., & Löser, C. J. (2013). Mating System and Hybridization of the Cyanus triumfetti and C. montanus Groups (Asteraceae). Folia Geobotanica, 48(4), 537-554. doi:10.1007/s12224-013-9155-3Španiel, S., Marhold, K., Hodálová, I., & Lihová, J. (2008). Diploid and Tetraploid Cytotypes of Centaurea stoebe (Asteraceae) in Central Europe: Morphological Differentiation and Cytotype Distribution Patterns. Folia Geobotanica, 43(2), 131-158. doi:10.1007/s12224-008-9008-7HARDY, O. J., VANDERHOEVEN, S., DE LOOSE, M., & MEERTS, P. (2000). Ecological, morphological and allozymic differentiation between diploid and tetraploid knapweeds (Centaurea jacea) from a contact zone in the Belgian Ardennes. New Phytologist, 146(2), 281-290. doi:10.1046/j.1469-8137.2000.00631.xFerriol, M., Garmendia, A., Ruiz, J. J., Merle, H., & Boira, H. (2012). Morphological and molecular analysis of natural hybrids between the diploidCentaurea asperaL. and the tetraploidC. seridisL. (Compositae). Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology, 146(sup1), 86-100. doi:10.1080/11263504.2012.727878Ferriol, M., Merle, H., & Garmendia, A. (2014). Microsatellite evidence for low genetic diversity and reproductive isolation in tetraploidCentaurea seridis(Asteraceae) coexisting with diploidCentaurea asperaand triploid hybrids in contact zones. Botanical Journal of the Linnean Society, 176(1), 82-98. doi:10.1111/boj.12194Garmendia, A., Ferriol, M., Juarez, J., Zając, A., Kałużny, K., & Merle, H. (2015). A rare case of a natural contact zone in Morocco between an autopolyploid and an allopolyploid ofCentaurea asperawith sterile tetraploid hybrids. Plant Biology, 17(3), 746-757. doi:10.1111/plb.12284Petit, C., Bretagnolle, F., & Felber, F. (1999). Evolutionary consequences of diploid–polyploid hybrid zones in wild species. Trends in Ecology & Evolution, 14(8), 306-311. doi:10.1016/s0169-5347(99)01608-0Thorsson, A. T., Palsson, S., Sigurgeirsson, A., & Anamthawat-Jonsson, K. (2007). Morphological Variation among Betula nana (diploid), B. pubescens (tetraploid) and their Triploid Hybrids in Iceland. Annals of Botany, 99(6), 1183-1193. doi:10.1093/aob/mcm060Husband And, B. C., & Schemske, D. W. (2000). Ecological mechanisms of reproductive isolation between diploid and tetraploidChamerion angustifolium. Journal of Ecology, 88(4), 689-701. doi:10.1046/j.1365-2745.2000.00481.xKruskal, W. H., & Wallis, W. A. (1952). Use of Ranks in One-Criterion Variance Analysis. Journal of the American Statistical Association, 47(260), 583-621. doi:10.1080/01621459.1952.10483441Dunn, O. J. (1961). Multiple Comparisons among Means. Journal of the American Statistical Association, 56(293), 52-64. doi:10.1080/01621459.1961.10482090HARVILLE, D. A. (1974). Bayesian inference for variance components using only error contrasts. Biometrika, 61(2), 383-385. doi:10.1093/biomet/61.2.383McCullagh, P., & Nelder, J. A. (1989). 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Reproductive isolation between diploid and tetraploid cytotypes of Libidibia ferrea (= Caesalpinia ferrea) (Leguminosae): ecological and taxonomic implications. Plant Systematics and Evolution, 298(7), 1371-1381. doi:10.1007/s00606-012-0643-3Greiner, R., & Oberprieler, C. (2012). The role of inter-ploidy block for reproductive isolation of the diploid Leucanthemum pluriflorum Pau (Compositae, Anthemideae) and its tetra- and hexaploid relatives. Flora - Morphology, Distribution, Functional Ecology of Plants, 207(9), 629-635. doi:10.1016/j.flora.2012.07.001Ferrer, M. M., & Good-Avila, S. V. (2006). Macrophylogenetic analyses of the gain and loss of self-incompatibility in the Asteraceae. New Phytologist, 173(2), 401-414. doi:10.1111/j.1469-8137.2006.01905.xSun, M., & Ritland, K. (1998). Mating system of yellow starthistle (Centaurea solstitialis), a successful colonizer in North America. Heredity, 80(2), 225-232. doi:10.1046/j.1365-2540.1998.00290.xHusband, B. C., & Sabara, H. A. 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An Extended Model of Moral Outrage at Corporate Social Irresponsibility

The final publication is available at Springer via http://dx.doi.org/ 10.1007/s10551-014-2487-

Dissociations in the effects of beta2-adrenergic receptor agonists on cAMP formation and superoxide production in human neutrophils: Support for the concept of functional selectivity

In neutrophils, activation of the beta2-adrenergic receptor (beta2AR), a Gs-coupled receptor, inhibits inflammatory responses, which could be therapeutically exploited. The aim of this study was to evaluate the effects of various beta2AR ligands on adenosine-3',5'-cyclic monophosphate (cAMP) accumulation and N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP)-induced superoxide anion (O2*-) production in human neutrophils and to probe the concept of ligand-specific receptor conformations (also referred to as functional selectivity or biased signaling) in a native cell system. cAMP concentration was determined by HPLC/tandem mass spectrometry, and O2*- formation was assessed by superoxide dismutase-inhibitable reduction of ferricytochrome c. beta2AR agonists were generally more potent in inhibiting fMLP-induced O2*- production than in stimulating cAMP accumulation. (-)-Ephedrine and dichloroisoproterenol were devoid of any agonistic activity in the cAMP assay, but partially inhibited fMLP-induced O2*- production. Moreover, (-)-adrenaline was equiefficacious in both assays whereas the efficacy of salbutamol was more than two-fold higher in the O2*- assay. In contrast to the agonists, the effects of beta2AR antagonists were comparable between the two parameters on neutrophils. Differences between the data from neutrophils and recombinant test systems were observed for the beta2AR agonists as well as for the beta2AR antagonists. Lastly, we obtained no evidence for an involvement of protein kinase A in the inhibition of fMLP-induced O2*- production after beta2AR-stimulation, although, in principle, cAMP-increasing substances can inhibit O2*- production. Taken together, our data corroborate the concept of ligand-specific receptor conformations with unique signaling capabilities and suggest that the beta2AR inhibits O2*- production in a cAMP-independent manner

The population genetics of sporophytic self-incompatibility in Senecio squalidus L. (Asteraceae) I: S allele diversity in a natural population

Twenty-six individuals of the sporophytic self-incompatible (SSI) weed, Senecio squalidus were crossed in a full diallel to determine the number and frequency of S alleles in an Oxford population. Incompatibility phenotypes were determined by fruit-set results and the mating patterns observed fitted a SSI model that allowed us to identify six S alleles. Standard population S allele number estimators were modified to deal with S allele data from a species with SSI. These modified estimators predicted a total number of approximately six S alleles for the entire Oxford population of S. squalidus. This estimate of S allele number is low compared to other estimates of S allele diversity in species with SSI. Low S allele diversity in S. squalidus is expected to have arisen as a consequence of a disturbed population history since its introduction and subsequent colonisation of the British Isles. Other features of the SSI system in S. squalidus were also investigated: (a) the strength of self-incompatibility response; (b) the nature of S allele dominance interactions; and (c) the relative frequencies of S phenotypes. These are discussed in view of the low S allele diversity estimates and the known population history of S. squalidus.