Experimental evolution of adaptive divergence under varying degrees of gene flow

Adaptive divergence is the key evolutionary process generating biodiversity by means of natural selection. Yet, the conditions under which it can arise in the presence of gene flow remain contentious. To address this question, we subjected 132 sexually reproducing fission yeast populations, sourced from two independent genetic backgrounds, to disruptive ecological selection and manipulated the level of migration between environments. Contrary to theoretical expectations, adaptive divergence was most pronounced when migration was either absent (allopatry) or maximal (sympatry), but was much reduced at intermediate rates (parapatry and local mating). This effect was apparent across central life-history components (survival, asexual growth and mating) but differed in magnitude between ancestral genetic backgrounds. The evolution of some fitness components was constrained by pervasive negative correlations (trade-off between asexual growth and mating), while others changed direction under the influence of migration (for example, survival and mating). In allopatry, adaptive divergence was mainly conferred by standing genetic variation and resulted in ecological specialization. In sympatry, divergence was mainly mediated by novel mutations enriched in a subset of genes and was characterized by the repeated emergence of two strategies: an ecological generalist and an asexual growth specialist. Multiple loci showed consistent evidence for antagonistic pleiotropy across migration treatments providing a conceptual link between adaptation and divergence. This evolve-and-resequence experiment shows that rapid ecological differentiation can arise even under high rates of gene flow. It further highlights that adaptive trajectories are governed by complex interactions of gene flow, ancestral variation and genetic correlations

The prevalence of musculoskeletal diseases among casual dock workers Prevalecía de enfermedades musculoesqueléticos entre trabajadores portuarios apulsos Prevalência de doenças musculoesqueléticas entre trabalhadores portuários avulsos

This study identified the prevalence of work-related musculoskeletal disorders among casual dockworkers. This is a retrospective and quantitative study, the data sources of which included the medical files of dockworkers from 2000 to 2009. Data were collected in a medical service for dockworkers using a previously developed form; descriptive quantitative analysis was performed. Ethical aspects were complied with. A total of 15.8% of the diagnoses identified among male workers referred to musculoskeletal disorders. Individuals older than 52 years of age and with more than 21 years working in the field predominated. The most frequent musculoskeletal diseases included low back pain (38.8%), tendinitis (19.7%), and neck pain (12.5%). These diseases can be prevented through health interventions, confirming the importance of developing clinical support in nursing in order to improve the quality of life of dockworkers.<br>Este estudio tuvo como objetivo identificar la prevalecía de enfermedades osteomusculares relacionadas al trabajo entre trabajadores portuarios sin registro. Estudio cuantitativo, retrospectivo. La fuente de datos las tablas de atención medica de los trabajadores portuarios sin registro en el período de 2000 a 2009. La colecta de datos fue realizada en un Servicio de Medicina del Trabajo Portuario a partir de un formulario predeterminado. Se procedió en el análisis cuantitativo descriptivo de los datos. Los aspectos éticos fueran respetados. Se identificó 15,8% diagnósticos de enfermedades osteomusculares, entre trabajadores del sexo masculino. Predominaran individuos con más de 52 años de edad y con tiempo de actuación laboral superior a 21 años. Las principales enfermedades fueran de lumbalgia (38,8%), tendinitis (19,7%) y cervicalgía (12,5%). Las enfermedades osteomusculares mas prevalentes fueran las lumbalgías, tendinitis y cervicalgías, las cuales pueden prevenirse por medio de acciones interventoras y evaluativas en salud, ratificando la importancia de construir subsidios clínicos en enfermería que colaboren para la cualidad de vida del trabajador portuario.<br>O objetivo deste estudo foi identificar a prevalência de doenças musculoesqueléticas relacionadas ao trabalho, entre trabalhadores portuários avulsos. É estudo quantitativo, retrospectivo. A fonte de dados constituiu-se de fichas de atendimento médico dos trabalhadores portuários avulsos, no período de 2000 a 2009. A coleta de dados foi realizada em um serviço de medicina do trabalho portuário, a partir de formulário pré-determinado. Procedeu-se à análise quantitativa descritiva. Aspectos éticos foram respeitados. Identificaram-se 15,8% de diagnósticos de doenças osteomusculares, entre trabalhadores do sexo masculino. Predominaram indivíduos com mais de 52 anos de idade e com tempo de atuação laboral superior a 21 anos. As doenças osteomusculares prevalentes foram lombalgias (38,8%), tendinites (19,7%) e cervicalgias (12,5%), que podem ser prevenidas por meio de ações interventoras em saúde, ratificando a importante construção de subsídios clínicos em enfermagem para a qualidade do trabalho portuário