Global gene flow releases invasive plants from environmental constraints on genetic diversity

When plants establish outside their native range, their ability to adapt to the new environment is influenced by both demography and dispersal. However, the relative importance of these two factors is poorly understood. To quantify the influence of demography and dispersal on patterns of genetic diversity underlying adaptation, we used data from a globally distributed demographic research network comprising 35 native and 18 nonnative populations of Plantago lanceolata. Species-specific simulation experiments showed that dispersal would dilute demographic influences on genetic diversity at local scales. Populations in the native European range had strong spatial genetic structure associated with geographic distance and precipitation seasonality. In contrast, nonnative populations had weaker spatial genetic structure that was not associated with environmental gradients but with higher within-population genetic diversity. Our findings show that dispersal caused by repeated, long-distance, human-mediated introductions has allowed invasive plant populations to overcome environmental constraints on genetic diversity, even without strong demographic changes. The impact of invasive plants may, therefore, increase with repeated introductions, highlighting the need to constrain future introductions of species even if they already exist in an area

Review of biological risks associated with the collection of municipal wastes.

In many countries, the management of household waste has recently changed with an increased focus upon waste sorting resulting in lower collection frequency for some waste fractions. A consequence of this is the potential for increased growth of microorganisms in the waste before collection, which can lead to an increased exposure via inhalation for waste collection workers. Through a review of the literature, we aimed to evaluate risks caused by waste collecting workers' exposure to bioaerosols and to illuminate potential measures to reduce the exposure. Across countries and waste types, median exposure to fungi, bacteria, and endotoxin were typically around 10 <sup>4</sup> colony forming units (cfu)/m <sup>3</sup> , 10 <sup>4</sup> cfu/m <sup>3</sup> , and 10 EU/m <sup>3</sup> , respectively. However, some studies found 10-20+ times higher or lower median exposure levels. It was not clear how different types of waste influence the occupational exposure levels. Factors such as high loading, ventilation in and cleaning of drivers' cabs, increased collection frequency, waste in sealed sacks, and use of hand sanitizer reduce exposure. Incidences of gastrointestinal problems, irritation of the eye and skin and symptoms of organic dust toxic syndrome have been reported in workers engaged in waste collection. Several studies reported a correlation between bioaerosol exposure level and reduced lung function as either a short or a long term effect; exposure to fungi and endotoxin is often associated with an inflammatory response in exposed workers. However, a better understanding of the effect of specific microbial species on health outcomes is needed to proceed to more reliable risk assessments. Due to the increasing recycling effort and to the effects of global warming, exposure to biological agents in this working sector is expected to increase. Therefore, it is important to look ahead and plan future measures as well as improve methods to prevent long and short-term health effects