Genetics of decayed sexual traits in a parasitoid wasp with endosymbiont-induced asexuality.

Trait decay may occur when selective pressures shift, owing to changes in environment or life style, rendering formerly adaptive traits non-functional or even maladaptive. It remains largely unknown if such decay would stem from multiple mutations with small effects or rather involve few loci with major phenotypic effects. Here, we investigate the decay of female sexual traits, and the genetic causes thereof, in a transition from haplodiploid sexual reproduction to endosymbiont-induced asexual reproduction in the parasitoid wasp Asobara japonica. We take advantage of the fact that asexual females cured of their endosymbionts produce sons instead of daughters, and that these sons can be crossed with sexual females. By combining behavioral experiments with crosses designed to introgress alleles from the asexual into the sexual genome, we found that sexual attractiveness, mating, egg fertilization and plastic adjustment of offspring sex ratio (in response to variation in local mate competition) are decayed in asexual A. japonica females. Furthermore, introgression experiments revealed that the propensity for cured asexual females to produce only sons (because of decayed sexual attractiveness, mating behavior and/or egg fertilization) is likely caused by recessive genetic effects at a single locus. Recessive effects were also found to cause decay of plastic sex-ratio adjustment under variable levels of local mate competition. Our results suggest that few recessive mutations drive decay of female sexual traits, at least in asexual species deriving from haplodiploid sexual ancestors.

A Framework for Analyzing Language and Welfare

The paper proposes a general model that will encompass trade and social benefits of a common language, a preference for a variety of languages, the fundamental role of translators, an emotional attachment to maternal language, and the threat that globalization poses to the vast majority of languages. With respect to people’s emotional attachment, the model considers minorities to suffer losses from the subordinate status of their language. In addition, the model treats the threat to minority language as coming from the failure of the parents in the minority to transmit their maternal language (durably) to their children. Some familiar results occur. In particular, we encounter the usual social inefficiencies of decentralized solutions to language learning when the sole benefits of the learning are communicative benefits (though translation intervenes). However, these social inefficiencies assume a totally different air when the con-sumer gains of variety are brought in. One fundamental aim of the paper is to bring together contributions to the economics of language from labor economics, network externalities and international trade that are typically treated separately.

A Framework for Analyzing Language and Welfare

The paper proposes a general model that will encompass trade and social benefits of a common language, a preference for a variety of languages, the fundamental role of translators, an emo-tional attachment to maternal language, and the threat that globalization poses to the vast ma-jority of languages. With respect to people’s emotional attachment, the model considers minor-ities to suffer losses from the subordinate status of their language. In addition, the model treats the threat to minority language as coming from the failure of the parents in the minority to transmit their maternal language (durably) to their children. Some familiar results occur. In particular, we encounter the usual social inefficiencies of decentralized solutions to language learning when the sole benefits of the learning are communicative benefits (though translation intervenes). However, these social inefficiencies assume a totally different air when the con-sumer gains of variety are brought in. One fundamental aim of the paper is to bring together contributions to the economics of language from labor economics, network externalities and international trade that are typically treated separately.

Fine structural variations of alphabetaTCRs selected by vaccination with natural versus altered self-antigen in melanoma patients.

Immunotherapy of cancer is often performed with altered "analog" peptide Ags optimized for HLA class I binding, resulting in enhanced immunogenicity, but the induced T cell responses require further evaluation. Recently, we demonstrated fine specificity differences and enhanced recognition of naturally presented Ag by T cells after vaccination with natural Melan-A/MART-1 peptide, as compared with analog peptide. In this study, we compared the TCR primary structures of 1489 HLA-A*0201/Melan-A(26-35)-specific CD8 T cells derived from both cohorts of patients. Although a strong preference for TRAV12-2 segment usage was present in nearly all patients, usage of particular TRAJ gene segments and CDR3alpha composition differed slightly after vaccination with natural vs analog peptide. Moreover, TCR beta-chain repertoires were broader after natural than analog peptide vaccination. In all patients, we observed a marked conservation of the CDR3beta amino acid composition with recurrent sequences centered on a glycyl-leucyl/valyl/alanyl-glycyl motif. In contrast to viral-specific TCR repertoires, such "public" motifs were primarily expressed by nondominant T cell clonotypes, which contrasted with "private" CDR3beta signatures frequently found in T cell clonotypes that dominated repertoires of individual patients. Interestingly, no differences in functional avidity were observed between public and private T cell clonotypes. Collectively, our data indicate that T cell repertoires generated against natural or analog Melan-A peptide exhibited slightly distinct but otherwise overlapping and structurally conserved TCR features, suggesting that the differences in binding affinity/avidity of TCRs toward pMHC observed in the two cohorts of patients are caused by subtle structural TCR variations.

A Behavioural Model of Choice in the Presence of Decision Conflict

This paper proposes a model of choice that does not assume completeness of the decision maker’s preferences. The model explains in a natural way, and within a unified framework of choice when preference-incomparable options are present, four behavioural phenomena: the attraction effect, choice deferral, the strengthening of the attraction effect when deferral is per-missible, and status quo bias. The key element in the proposed decision rule is that an individual chooses an alternative from a menu if it is worse than no other alternative in that menu and is also better than at least one. Utility-maximising behaviour is included as a special case when preferences are complete. The relevance of the partial dominance idea underlying the proposed choice procedure is illustrated with an intuitive generalisation of weakly dominated strategies and their iterated deletion in games with vector payoffs.

Stochastic Choice and Consideration Sets

We model a boundedly rational agent who suffers from limited attention. The agent considers each feasible alternative with a given (unobservable) probability, the attention parameter, and then chooses the alternative that maximises a preference relation within the set of considered alternatives. We show that this random choice rule is the only one for which the impact of removing an alternative on the choice probability of any other alternative is asymmetric and menu independent. Both the preference relation and the attention parameters are identi fied uniquely by stochastic choice data.

Two Studies on the Interplay between Social Preferences and Individual Biological Features

Biological features and social preferences have been studied separately as factors influencing human strategic behaviour. We run two studies in order to explore the interplay between these two sets of factors. In the first study, we investigate to what extent social preferences may have some biological underpinnings. We use simple one-shot distribution experiments to attribute subjects one out of four types of social preferences: Self-interested (SI), Competitive (C), Inequality averse (IA) and Efficiency-seeking (ES). We then investigate whether these four groups display differences in their levels of facial Fluctuating Asymmetry (FA) and in proxies for exposure to testosterone during phoetal development and puberty. We observe that development-related biological features and social preferences are relatively independent. In the second study, we compare the relative weight of these two set of factors by studying how they affect subjects’ behaviour in the Ultimatum Game (UG). We find differences in offers made and rejection rates across the four social preference groups. The effect of social preferences is stronger than the effect of biological features even though the latter is significant. We also report a novel link between facial masculinity (a proxy for exposure to testosterone during puberty) and rejection rates in the UG. Our results suggest that biological features influence behaviour both directly and through their relation with the type of social preferences that individuals hold.

Unilateral Emissions Mitigation, Spillovers, and Global Learning

What's the role of unilateral measures in global climate change mitigation in a post-Durban, post 2012 global policy regime? We argue that under conditions of preference heterogeneity, unilateral emissions mitigation at a subnational level may exist even when a nation is unwilling to commit to emission cuts. As the fraction of individuals unilaterally cutting emissions in a global strongly connected network of countries evolves over time, learning the costs of cutting emissions can result in the adoption of such activities globally and we establish that this will indeed happen under certain assumptions. We analyze the features of a policy proposal that could accelerate convergence to a low carbon world in the presence of global learning.

What is the Causal Effect of Information and Learning about a Public Good on Willingness to Pay?

In this study we elicit agents’ prior information set regarding a public good, exogenously give information treatments to survey respondents and subsequently elicit willingness to pay for the good and posterior information sets. The design of this field experiment allows us to perform theoretically motivated hypothesis testing between different updating rules: non-informative updating, Bayesian updating, and incomplete updating. We find causal evidence that agents imperfectly update their information sets. We also field causal evidence that the amount of additional information provided to subjects relative to their pre-existing information levels can affect stated WTP in ways consistent overload from too much learning. This result raises important (though familiar) issues for the use of stated preference methods in policy analysis.

Imperfect Attention and Menu Evaluation

We model the choice behaviour of an agent who suffers from imperfect attention. We define inattention axiomatically through preference over menus and endowed alternatives: an agent is inattentive if it is better to be endowed with an alternative a than to be allowed to pick a from a menu in which a is is the best alternative. This property and vNM rationality on the domain of menus and alternatives imply that the agent notices each alternative with a given menu-dependent probability (attention parameter) and maximises a menu independent utility function over the alternatives he notices. Preference for flexibility restricts the model to menu independent attention parameters as in Manzini and Mariotti [19]. Our theory explains anomalies (e.g. the attraction and compromise effect) that the Random Utility Model cannot accommodate.

Autonomy-enhancing paternalism

We present a form of soft paternalism called "autonomy-enhancing paternalism" that seeks to in-crease individual well-being by facilitating the individual ability to make critically reflected, autonomous decisions. The focus of autonomy-enhancing paternalism is on helping individuals to become better decision-makers, rather than on helping them by making better decisions for them. Autonomy-enhancing paternalism acknowledges that behavioral interventions can change the strength of decision-making anomalies over time, and favors those interventions that improve, rather than reduce, individuals ability to make good and unbiased decisions. By this it prevents manipulation of the individual by the soft paternalist, accounts for the heterogeneity of individuals, and counteracts slippery slope arguments by decreasing the probability of future paternalistic interventions. Moreover, autonomy-enhancing paternalism can be defended based on both liberal values and welfare considerations.

Choice, Deferral and Consistency

In this paper we study decision making in situations where the individual’s preferences are not assumed to be complete. First, we identify conditions that are necessary and sufficient for choice behavior in general domains to be consistent with maximization of a possibly incomplete preference relation. In this model of maximally dominant choice, the agent defers/avoids choosing at those and only those menus where a most preferred option does not exist. This allows for simple explanations of conflict-induced deferral and choice overload. It also suggests a criterion for distinguishing between indifference and incomparability based on observable data. A simple extension of this model also incorporates decision costs and provides a theoretical framework that is compatible with the experimental design that we propose to elicit possibly incomplete preferences in the lab. The design builds on the introduction of monetary costs that induce choice of a most preferred feasible option if one exists and deferral otherwise. Based on this design we found evidence suggesting that a quarter of the subjects in our study had incomplete preferences, and that these made significantly more consistent choices than a group of subjects who were forced to choose. The latter effect, however, is mitigated once data on indifferences are accounted for.

Integer Programming on Domains Containing Inseparable Ordered Paris

Using the integer programming approach introduced by Sethuraman, Teo, and Vohra (2003), we extend the analysis of the preference domains containing an inseparable ordered pair, initiated by Kalai and Ritz (1978). We show that these domains admit not only Arrovian social welfare functions \without ties," but also Arrovian social welfare functions \with ties," since they satisfy the strictly decomposability condition introduced by Busetto, Codognato, and Tonin (2012). Moreover, we go further in the comparison between Kalai and Ritz (1978)'s inseparability and Arrow (1963)'s single-peak restrictions, showing that the former condition is more \respectable," in the sense of Muller and Satterthwaite (1985).

Choosing on Influence

Interaction, the act of mutual influence between two or more individuals, is an essential part of daily life and economic decisions. Yet, micro-foundations of interaction are unexplored. This paper presents a first attempt to this purpose. We study a decision procedure for interacting agents. According to our model, interaction occurs since individuals seek influence for those issues that they cannot solve on their own. Following a choice-theoretic approach, we provide simple properties that aid to detect interacting individuals. In this case, revealed preference analysis not only grants the underlying preferences but also the influence acquired. Our baseline model is based on two interacting individuals, though we extend the analysis to multi-individual environments.

Effects of different mating scenarios on embryo viability in brown trout.

Mating with attractive or dominant males is often predicted to offer indirect genetic benefits to females, but it is still largely unclear how important such non-random mating can be with regard to embryo viability. We sampled a natural population of adult migratory brown trout (Salmo trutta), bred them in vitro in a half-sib breeding design to separate genetic from maternal environmental effects, raised 2098 embryos singly until hatching, and exposed them experimentally to different levels of pathogen stress at a late embryonic stage. We found that the embryos' tolerance to the induced pathogen stress was linked to the major histocompatibility complex (MHC) of their parents, i.e. certain MHC genotypes appeared to provide better protection against infection than others. We also found significant additive genetic variance for stress tolerance. Melanin-based dark skin patterns revealed males with 'good genes', i.e. embryos fathered by dark coloured males had a high tolerance to infection. Mating with large and dominant males would, however, not improve embryo viability when compared to random mating. We used simulations to provide estimates of how mate choice based on MHC or melanin-based skin patterns would influence embryos' tolerance to the experimentally induced pathogen stress.