Evidence for an ecological cost of enhanced herbicide metabolism in Lolium rigidum

1. In some cases, evaluation of resource competitive interactions between herbicide resistant vs. susceptible weed ecotypes provides evidence for the expression of fitness costs associated with evolved herbicide-resistant gene traits. Such fitness costs impact in the ecology and evolutionary trajectory of resistant populations. 2. Neighbourhood experiments were performed to quantify competitive effects and responses between herbicide-susceptible (S) and resistant (R) Lolium rigidum individuals in which resistance is due to enhanced herbicide metabolism mediated by cytochrome P450. 3. In two-way competitive interactions between the S and R phenotypes, individuals of the S phenotype were the stronger effect competitors on both a per capita and per unit-size basis. The S phenotype also exhibited a stronger competitive response to wheat plants than did the R phenotype, displaying significantly greater (30%) above-ground biomass at the vegetative stage. When subjected to competition from wheat, R individuals produced significantly fewer reproductive tillers and allocated fewer resources to reproductive traits than individuals of the S phenotype. 4. The role of potential mechanisms underlying this resistance cost driven by traits such as plant size and tolerance to low resource availability, as well as the evolutionary implications of the results are discussed. 5. Synthesis. Evolved herbicide resistance due to enhanced-herbicide metabolism mediated by cytochrome-P450 in L. rigidum has been shown to be accompanied with an impaired ability to compete for resources. These results are consistent with the resource-based theory that predicts a negative trade-off between growth and plant defence

Fitness costs associated with evolved herbicide resistance alleles in plants

Predictions based on evolutionary theory suggest that the adaptive value of evolved herbicide resistance alleles may be compromised by the existence of fitness costs. There have been many studies quantifying the fitness costs associated with novel herbicide resistance alleles, reflecting the importance of fitness costs in determining the evolutionary dynamics of resistance. However, many of these studies have incorrectly defined resistance or used inappropriate plant material and methods to measure fitness. This review has two major objectives. First, to propose a methodological framework that establishes experimental criteria to unequivocally evaluate fitness costs. Second, to present a comprehensive analysis of the literature on fitness costs associated with herbicide resistance alleles. This analysis reveals unquestionable evidence that some herbicide resistance alleles are associated with pleiotropic effects that result in plant fitness costs. Observed costs are evident from herbicide resistance-endowing amino acid substitutions in proteins involved in amino acid, fatty acid, auxin and cellulose biosynthesis, as well as enzymes involved in herbicide metabolism. However, these resistance fitness costs are not universal and their expression depends on particular plant alleles and mutations. The findings of this review are discussed within the context of the plant defence trade-off theory and herbicide resistance evolution

Recent Developments in the Role of Protein Tyrosine Phosphatase 1B (PTP1B) as a Regulator of Immune Cell Signalling in Health and Disease

Peer reviewe

Essays in political economy and voting behaviour

This thesis explores how political preferences are shaped by institutions, economic conditions, and personality. Each chapter is a distinct contribution and provides a different perspective on the formation of political preferences and, ultimately, voting behaviour. These different approaches relate to the fields of comparative political economy, behavioural economics, and political psychology. Methodologically, this thesis is empirically applied and the results of these separate enquiries into political preferences are grounded in statistical analysis. A first substantive chapter introduces a median voter data set that provides insight into the ideological position of the electoral centre in over 50 democracies. A second chapter uses this new data and studies cross-national voting behaviour in 18 Western democracies over 1960-2003. It is found that electoral behaviour is closely related to the salience of the following economic institutions: labour organization, skill specificity, and public sector employment. This research shows that political preferences are endogenous to economic institutions and implies the existence of institutional advantages to partisan politics. A third substantive chapter focuses on ideological change in the United States and tests the proposition that voters advance a more liberal agenda in prosperous times and shift towards being more conservative in dire economic times. A reference-dependent utility model relates income growth to political preferences by way of the demand for public goods and the optimal tax rate. This work thus links voting behaviour to economic business cycles and shows that ideological change is endogenous to income growth rates. Finally, a fourth chapter presents the largest study to date of the influence of the big five personality traits on political ideology. In line with prior research in political psychology, it is found that openness to experience strongly predicts liberal ideology and that conscientiousness strongly predicts conservative ideology. A variety of childhood experiences are also studied that may have a differential effect on political ideology based on an individual's personality profile. The findings of this final chapter provide new evidence for the idea that differences in political preferences are deeply intertwined with variation in the nature and nurture of individual personalities. Generally, this thesis provides some new insights into the complex world of political preference formation and does so by exploring the influential role of institutions, economic conditions, and personality

Integrating biological knowledge into variable selection : an empirical Bayes approach with an application in cancer biology

Background: An important question in the analysis of biochemical data is that of identifying subsets of molecular variables that may jointly influence a biological response. Statistical variable selection methods have been widely used for this purpose. In many settings, it may be important to incorporate ancillary biological information concerning the variables of interest. Pathway and network maps are one example of a source of such information. However, although ancillary information is increasingly available, it is not always clear how it should be used nor how it should be weighted in relation to primary data. Results: We put forward an approach in which biological knowledge is incorporated using informative prior distributions over variable subsets, with prior information selected and weighted in an automated, objective manner using an empirical Bayes formulation. We employ continuous, linear models with interaction terms and exploit biochemically-motivated sparsity constraints to permit exact inference. We show an example of priors for pathway- and network-based information and illustrate our proposed method on both synthetic response data and by an application to cancer drug response data. Comparisons are also made to alternative Bayesian and frequentist penalised-likelihood methods for incorporating network-based information. Conclusions: The empirical Bayes method proposed here can aid prior elicitation for Bayesian variable selection studies and help to guard against mis-specification of priors. Empirical Bayes, together with the proposed pathway-based priors, results in an approach with a competitive variable selection performance. In addition, the overall procedure is fast, deterministic, and has very few user-set parameters, yet is capable of capturing interplay between molecular players. The approach presented is general and readily applicable in any setting with multiple sources of biological prior knowledge

L’intuizione di qualcos’altro. Lineamenti geografici di una catastrofe antropocenica

We are living in an age in which disasters are a basically constant backdrop of breaking news, but that can be named as natural provided only that we ignore the evolutionary path leading to the present situation. Namely, the present pandemic – interpreted as a stress test of our model of development – shows itself as a real «anthropocenic catastrophe». As a catastrophe, not only because of its unquestionable tragic impact on lives, but also, following René Thom, as an abrupt evolutionary discontinuity, as a catastrophe of a representation of the world. Anthropocenic, because, despite the ongoing debate over such concept, it is hard to ascribe SARS- CoV-2 to nature. The present essay aims at framing the pandemic within the model of territoriality by Claude Raffestin, showing how the neoliberal paradigm has taken to the extreme its choices in terms of blind trust in digitalisation and automation (algocracy), regarding decision-making, work, and health, so finally disrupting the evolutionary inner adjustment process through which territorialities have been able through time to settle singularities into a common framework

Community structure and intertidal zonation of the macrobenthos on a macrotidal, ultra-dissipative sandy beach: summer-winter comparison

Community structure and intertidal zonation of the macrobenthos on a macrotidal, ultra-dissipative beach were studied. On the beach of De Panne, Belgium, six transects perpendicular to the waterline (each with five stations) were sampled in September 1995 (summer) and March 1996 (winter). The 30 stations were distributed across the continuum from mean high water spring to mean low water spring in order to sample the macrobenthos at different levels of elevation. The 39 species found had total densities up to 5,500 ind m-2 in summer and 1,400 ind m-2 in winter. The highest densities were found in the spionid polychaetes Scolelepis squamata and Spio filicornis, the nephtyid polychaete Nephtys cirrosa, the cirolanid isopod Eurydice pulchra, and the haustorid amphipods Bathyporeia spp. Based on species composition, specific densities, and biomass, two species associations were defined: a relatively species-poor, high intertidal species association, dominated by S. squamata and with an average density of 1,413 ind m-2 and biomass of 808 mg AFDW m-2 (summer); and a relatively species-rich, low intertidal species association, dominated by N. cirrosa, and with an average density of 104 ind m-2 and biomass of 162 mg AFDW m-2 in summer. For both seasons, the high intertidal species association was restricted in its intertidal distribution between the mean tidal and the mean high-water spring level, whereas the low intertidal species association was found from the mean tidal level to the subtidal. The latter showed good affinities with the subtidal N. cirrosa species association, occurring just offshore of De Panne beach, confirming the existence of a relationship between the low intertidal and subtidal macrobenthic species associations. Summer-winter comparison revealed a strong decrease in densities and biomass in the high intertidal zone during winter. Habitat continuity of the low intertidal zone with the subtidal allows subtidal organisms to repopulate the low intertidal zone