Determining capable guardians in rape incidents

Crime prevention is crucial to safeguard individual freedom and maintain social order. This is especially true in rape incidents as consequences may have long-lasting physical and mental effects on individual victims and great social costs. This study employs the routine activities theory to examine whether and how capable guardians (e.g., the presence of bystanders, the use of physical resistance, forceful verbal resistance or non-forceful verbal resistance) are likely to affect rape outcomes; A sample of 638 females who were the victim of a single offender male perpetrated rape incident was drawn from the National Crime Victimization Survey, ranging from 1992 to 2003. The analysis of univariate, bivariate and binary logistic regression revealed that the presence of bystanders, physical resistance and forceful verbal resistance were predictive of attempted rape incidents, whereas the use of non-forceful verbal resistance was predictive of completed rape incidents. Theoretical and practical implications were discussed

Network-constrained models of liberalized electricity markets: the devil is in the details

Numerical models for electricity markets are frequently used to inform and support decisions. How robust are the results? Three research groups used the same, realistic data set for generators, demand and transmission network as input for their numerical models. The results coincide when predicting competitive market results. In the strategic case in which large generators can exercise market power, the predicted prices differed significantly. The results are highly sensitive to assumptions about market design, timing of the market and assumptions about constraints on the rationality of generators. Given the same assumptions the results coincide. We provide a checklist for users to understand the implications of different modelling assumptions

Life history and mating systems select for male biased parasitism mediated through natural selection and ecological feedbacks

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordMales are often the 'sicker' sex with male biased parasitism found in a taxonomically diverse range of species. There is considerable interest in the processes that could underlie the evolution of sex-biased parasitism. Mating system differences along with differences in lifespan may play a key role. We examine whether these factors are likely to lead to male-biased parasitism through natural selection taking into account the critical role that ecological feedbacks play in the evolution of defence. We use a host-parasite model with two-sexes and the techniques of adaptive dynamics to investigate how mating system and sexual differences in competitive ability and longevity can select for a bias in the rates of parasitism. Male-biased parasitism is selected for when males have a shorter average lifespan or when males are subject to greater competition for resources. Male-biased parasitism evolves as a consequence of sexual differences in life-history that produce a greater proportion of susceptible females than males and therefore reduce the cost of avoiding parasitism in males. Different mating systems such as monogamy, polygyny or polyandry did not produce a bias in parasitism through these ecological feedbacks but may accentuate an existing bias.Flora S. Bacelar acknowledges support from the Balaric Government, and from Spanish MICINN and FEDER through project FISICOS (FIS200760327) and to Emílio Hernández-García for reading the article and useful discussions. Andrew White is supported by a Royal Society of Edinburgh and Scottish Government Support Research Fellowship. Mike Boots is supported by a Leverhulme Trust Fellowship

The Role of Trade-off Shapes in the Evolution of Parasites in Spatial Host Populations: An Approximate Analytical Approach

Given the substantial changes in mixing in many populations, there is considerable interest in the role that spatial structure can play in the evolution of disease. Here we examine the role of different trade-off shapes in the evolution of parasites in a spatially structured host population where infection can occur locally or globally. We develop an approximate adaptive dynamic analytical approach, to examine how the evolutionarily stable (ES) virulence depends not only on the fraction of global infection/transmission but also on the shape of the trade-off between transmission and virulence. Our analysis can successfully predict the ES virulence found previously by simulation of the full system. The analysis confirms that when there is a linear trade-off between transmission and virulence spatial structure may lead to an ES virulence that increases as the proportion of global transmission increases. However, we also show that the ESS disappears above a threshold level of global infection, leading to maximization. In addition just below this threshold, there is the possibility of evolutionary bi-stabilities. When we assume the realistic trade-off between transmission and virulence that results in an ESS in the classical mixed model, we find that spatial structure can increase or decrease the ES virulence. A relatively high proportion of local infection reduces virulence but intermediate levels can select for higher virulence. Our work not only emphasizes the importance of spatial structure to the evolution of parasites, but also makes it clear that situations between the local and the global need to be considered. We also emphasize the key role that the shape of trade-offs plays in evolutionary outcomes

The Role of Trade-off Shapes in the Evolution and Coexistence of Virulence in Spatial Host-Parasite Interactions: An Approximate Adaptive Dynamical Approach

We propose a new analysis for the evolution of virulence of pathogen in a spatially structured host population where each site of a regular lattice is either occupied by a susceptible or by an infected, or is empty. We assume that reproduction by susceptible individuals occurs locally but infection by a contact of susceptible and infected hosts occurs either locally or globally with a certain proportion. We examine by combining Monte-Carlo simulation and adaptive dynamics approach, how the evolutionarily stable (ESS) virulence depends on the fraction of global infection/transmission and the trade-off between transmission and virulence in the model investigated by Boots and Sasaki (1999). Our analysis developed in this paper can successfully predicted the ESS virulence found in the previous papers, and reveals followings: [1] With a linear trade-off, as is reported by previous studies, there is an ESS virulence when the proportion of global infection is small. We newly find that, if we increase the proportion, the ESS disappears when the proportion exceeds a certain threshold value, and proportions just below the threshold, there are evolutionary bi-stabilities. [2] With a non-linear trade-off, there can be no monomorphic ESS; instead, the evolutionary competition between many parasite genotypes differing in their virulence gives rise to an evolutionarily stable coalition of pathogen strains with markedly different virulence (dimorphic ESS virulence) with a middle proportion of global transmission. These analytical results well illustrate the results by Monte-Carlo simulations. Since coexistence and evolutionary bistability are not impossible in the model we investigate in this paper, these are apparently derived by the effect of spatial structure

Network-constrained models of liberalized electricity markets: the devil is in the details

Numerical models for electricity markets are frequently used to inform and support decisions. How robust are the results? Three research groups used the same, realistic data set for generators, demand and transmission network as input for their numerical models. The results coincide when predicting competitive market results. In the strategic case in which large generators can exercise market power, the predicted prices differed significantly. The results are highly sensitive to assumptions about market design, timing of the market and assumptions about constraints on the rationality of generators. Given the same assumptions the results coincide. We provide a checklist for users to understand the implications of different modelling assumptions.Market power, Electricity, Networks, Numeric models, Model comparison

Host lifespan and the evolution of resistance to multiple parasites.

Published onlineJournal ArticleThis is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.Hosts are typically challenged by multiple parasites, but to date theory on the evolution of resistance has mainly focused on single infections. We develop a series of models that examine the impact of multiple parasites on the evolution of resistance under the assumption that parasites coexist at the host population scale as a consequence of superinfection. In this way, we are able to explicitly examine the impact of ecological dynamics on the evolutionary outcome. We use our models to address a key question of how host lifespan affects investment in resistance to multiple parasites. We show that investment in costly resistance depends on the specificity of the immune response and on whether or not the focal parasite leads to more acute infection than the co-circulating parasite. A key finding is that investment in resistance always increases as the immune response becomes more general independently of whether it is the focal or the co-circulating parasite that exploits the host most aggressively. Long-lived hosts always invest more than short-lived hosts in both general resistance and resistance that is specific to relatively acute focal parasites. However, for specific resistance to parasites that are less acute than co-circulating parasites it is the short-lived hosts that are predicted to invest most. We show that these results apply whatever the mode of defence, that is whether it is through avoidance or through increased recovery, with or without acquired immunity, or through acquired immunity itself. As a whole, our results emphasize the importance of considering multiple parasites in determining optimal immune investment in eco-evolutionary systems.NERC. Grant Number: NE=K014617=

How specificity and epidemiology drive the coevolution of static trait diversity in hosts and parasites

This is the final version of the article. Available from the publisher via the DOI in this record.There is typically considerable variation in the level of infectivity of parasites and the degree of resistance of hosts within populations. This trait variation is critical not only to the evolutionary dynamics but also to the epidemiology, and potentially the control of infectious disease. However, we lack an understanding of the processes that generate and maintain this trait diversity. We examine theoretically how epidemiological feedbacks and the characteristics of the interaction between host types and parasites strains determine the coevolution of host-parasite diversity. The interactions include continuous characterizations of the key phenotypic features of classic gene-for-gene and matching allele models. We show that when there are costs to resistance in the hosts and infectivity in the parasite, epidemiological feedbacks may generate diversity but this is limited to dimorphism, often of extreme types, in a broad range of realistic infection scenarios. For trait polymorphism, there needs to be both specificity of infection between host types and parasite strains as well as incompatibility between particular strains and types. We emphasize that although the high specificity is well known to promote temporal "Red Queen" diversity, it is costs and combinations of hosts and parasites that cannot infect that will promote static trait diversity.MB was a fellow of the Wissenschaftskolleg zu Berlin 2010–2011 during the writing of this article, and we acknowledge the support from the Natural Environment Research Council (grant NE/K014617/1) to MB and AB

Spatial heterogeneity lowers rather than increases host-parasite specialization.

This is the final version of the article. Available from the publisher via the DOI in this record.Abiotic environmental heterogeneity can promote the evolution of diverse resource specialists, which in turn may increase the degree of host-parasite specialization. We coevolved Pseudomonas fluorescens and lytic phage ϕ2 in spatially structured populations, each consisting of two interconnected subpopulations evolving in the same or different nutrient media (homogeneous and heterogeneous environments, respectively). Counter to the normal expectation, host-parasite specialization was significantly lower in heterogeneous compared with homogeneous environments. This result could not be explained by dispersal homogenizing populations, as this would have resulted in the heterogeneous treatments having levels of specialization equal to or greater than that of the homogeneous environments. We argue that selection for costly generalists is greatest when the coevolving species are exposed to diverse environmental conditions and that this can provide an explanation for our results. A simple coevolutionary model of this process suggests that this can be a general mechanism by which environmental heterogeneity can reduce rather than increase host-parasite specialization.This project was funded by NERC (NE/G006938/2), BBSRC and the AXA Research Fund. ABu is supported by a Royal Society Wolfson Research Merit Award. ABe is supported by a Leverhulme Early Career Research Fellowship