Fission as a source of variation for group selection.

Without heritable variation natural selection cannot effect evolutionary change. In the case of group selection, there must be variation in the population of groups. Where does this variation come from? One source of variation is from the stochastic birth-death processes that occur within groups.

Impact of the COVID-19 pandemic on Bordetella pertussis infections in England.

Background: In March 2020, England went into its first lockdown in response to the COVID-19 pandemic. Restrictions eased temporarily, followed by second and third waves in October 2020 and January 2021. Recent data showed that the COVID-19 pandemic resulted in reduced transmission of some invasive diseases.

Acculturation drives the evolution of intergroup conflict.

Conflict between groups of individuals is a prevalent feature in human societies. A common theoretical explanation for intergroup conflict is that it provides benefits to individuals within groups in the form of reproduction-enhancing resources, such as food, territory, or mates. However, it is not always the case that conflict results from resource scarcity.

Group-level events are catalysts in the evolution of cooperation.

Group-level events, like fission and extinction, catalyze the evolution of cooperation in group-structured populations by creating new paths from uncooperative population states to more cooperative states. Group-level events allow cooperation to thrive under unfavorable conditions such as low intra-group assortment and moderate rates of migration, and can greatly speed up the evolution of cooperation when conditions are more favorable. The time-dependent effects of fission and extinction events are studied and illustrated here using a PDE model of a group-structured population based loosely on populations of hunter-gatherer tribes.

Hamilton's rule.

This paper reviews and addresses a variety of issues relating to inclusive fitness. The main question is: are there limits to the generality of inclusive fitness, and if so, what are the perimeters of the domain within which inclusive fitness works? This question is addressed using two well-known tools from evolutionary theory: the replicator dynamics, and adaptive dynamics. Both are combined with population structure.

A simple model of group selection that cannot be analyzed with inclusive fitness.

A widespread claim in evolutionary theory is that every group selection model can be recast in terms of inclusive fitness. Although there are interesting classes of group selection models for which this is possible, we show that it is not true in general. With a simple set of group selection models, we show two distinct limitations that prevent recasting in terms of inclusive fitness.

Studying the emergence of complicated group-level cultural traits requires a mathematical framework.

Understanding the cultural evolution of complicated group-level traits requires the mathematical formulation of a dynamical system with birth and death events at multiple levels, that is, at the level of individual humans and at the level of groups of humans. Both levels are characterized by cultural traits that have complicated transmission, innovation, and inheritance mechanisms and that can undergo a form of Lamarckian evolution.

Continuous-time models of group selection, and the dynamical insufficiency of kin selection models.

Traditionally, the process of group selection has been described mathematically by discrete-time models, and analyzed using tools like the Price equation. This approach makes implicit assumptions about the process that are not valid in general, like the central role of synchronized mass-dispersion and group re-formation events. In many important examples (like hunter-gatherer tribes) there are no mass-dispersion events, and the group-level events that do occur, like fission, fusion, and extinction, occur asynchronously.

Towards a general theory of group selection.

The longstanding debate about the importance of group (multilevel) selection suffers from a lack of formal models that describe explicit selection events at multiple levels. Here, we describe a general class of models for two-level evolutionary processes which include birth and death events at both levels. The models incorporate the state-dependent rates at which these events occur.

Hamilton's rule in multi-level selection models.

Hamilton's rule is regarded as a useful tool in the understanding of social evolution, but it relies on restrictive, overly simple assumptions. Here we model more realistic situations, in which the traditional Hamilton's rule generally fails to predict the direction of selection. We offer modifications that allow accurate predictions, but also show that these Hamilton's rule type inequalities do not predict long-term outcomes.

A stochastic model of evolutionary dynamics with deterministic large-population asymptotics.

An evolutionary birth-death process is proposed as a model of evolutionary dynamics. Agents residing in a continuous spatial environment X, play a game G, with a continuous strategy set S, against other agents in the environment. The agents' positions and strategies continuously change in response to other agents and to random effects.

Symptom domains of schizophrenia: the role of atypical antipsychotic agents.

Given their more obvious presentation, the reduction of positive symptoms and their associated behavioural problems have been considered the most important treatment outcome parameter in patients with schizophrenia. However, the development of the atypical antipsychotic agents in the early 1990s resulted in the adoption of more wide-reaching measures of therapeutic outcome. The aim of this review was to evaluate the efficacy of currently available atypical agents across multiple symptom domains of schizophrenia with a specific focus on negative symptoms, neurocognition, social functioning, quality of life and insight.

Smoking and schizophrenia: is symptom profile related to smoking and which antipsychotic medication is of benefit in reducing cigarette use?

Objective: Smoking rate is disproportionately high among patients with schizophrenia, resulting in significant morbidity and mortality. However, cigarette smoking has been reported to have beneficial effects on negative symptoms, extrapyramidal symptoms, cognitive functioning and mood symptoms. Therefore, smoking cessation may worsen disability in schizophrenia.

Strategies for improving adherence to second-generation antipsychotics in patients with schizophrenia by increasing ease of use.

Despite the advances in the treatment of patients with schizophrenia that have occurred since the introduction of the second-generation (atypical) antipsychotic agents, a leading cause of suboptimal outcome is poor patient adherence to oral medication. Partial adherence can be attributed to a number of factors, including lack of insight, cognitive dysfunction, a complicated treatment regimen, drug-related side effects, patient attitude, lack of patient education, and cultural factors. A number of strategies, including psychosocial interventions, cognitive-behavioral techniques, strategies that minimize side effects, and pharmacological approaches that increase ease of medication use, can be employed to support adherence and improve long-term outcomes.

The C/C genotype of the C957T polymorphism of the dopamine D2 receptor is associated with schizophrenia.

The T allele of the human dopamine D2 receptor (DRD2) gene C957T polymorphism is associated with reduced mRNA translation and stability. This results in decreased dopamine induced DRD2 upregulation and decreased in vivo D2 dopamine binding. Conversely, the C allele of the C957T polymorphism is not associated with such changes in mRNA leading to increased DRD2 expression.

Prolactin levels in antipsychotic treatment of patients with schizophrenia carrying the DRD2*A1 allele.

Background: Hyperprolactinaemia induced by D(2) dopamine receptor antagonist antipsychotic medication can result in significant health problems.

Aims: To examine the role of DRD2 polymorphism on prolactin levels in patients treated with antipsychotic medication.

Method: Antipsychotic drugs with different degrees of D(2) receptor binding were given to 144 patients with schizophrenia.

Impact of the physical and topographical characteristics of adsorbent solid-phases upon the fluidised bed recovery of plasmid DNA from Escherichia coli lysates.

A comparison is made of the performance of two types of adsorbent solid phases (commercially sourced Streamline composites and custom-assembled Zirblast pelliculates), derivatised with similar anion exchange chemistries and applied to the recovery of plasmid DNA from Escherichia coli extracts prepared by chemical lysis and coarse filtration. Streamline and Zirblast adsorbents were characterised by average particle diameters of 200 and 95 microm, densities of 1.16 and 3.