Correlates of substitution rate variation in mammalian protein-coding sequences

Background  

Rates of molecular evolution in different lineages can vary widely, and some of this variation might be predictable from aspects of species' biology. Investigating such predictable rate variation can help us to understand the causes of molecular evolution, and could also help to improve molecular dating methods. Here we present a comprehensive study of the life history correlates of substitution rate variation across the mammals, comparing results for mitochondrial and nuclear loci, and for synonymous and non-synonymous sites. We use phylogenetic comparative methods, refined to take into account the special nature of substitution rate data. Particular attention is paid to the widespread correlations between the components of mammalian life history, which can complicate the interpretation of results.     

Generation of Domestic Solid Waste in Rural Areas: Case Study of Remote Communities in the Brazilian Amazon

The Brazilian rural population is estimated to be around 30 million people and many rural areas do not have universal access to basic infrastructure services, including those related to solid waste. There are very few scientific studies on rural domestic solid waste and more investigative work is needed to provide information for appropriate solid waste management policies. This paper aims to characterize rural domestic solid waste in terms of quantity and quality. Amazonian rural communities were chosen for our case study. The issue of domestic solid waste was characterized both by means of interviews, at household level, and by a study of industrialized products traded in the communities located along the banks of the Juruá River, in the Brazilian Amazon. Quantitative results have shown that generation of solid waste in these rural communities reaches 0.5 kg/person/day. Organic matter represents 90 % of domestic solid waste generation and is mainly reused to feed animals and/or is composted using a method called paú. Inorganic solid waste (10 %) is either reused, burned or inadequately dumped in open sites. Based on these data, the annual production of solid waste is 437 tons per year in these communities. Since infrastructure services are virtually non-existent in this rural context, even this amount of solid waste may have a serious environmental impact, with negative effects on the population’s health, particularly in terms of hazardous waste. Even though solid waste management solutions for rural populations might not always be based on economic efficiency, decision makers responsible for development and planning should present solutions that are socially, technologically, environmentally and economically suitable for this context.     

<Emphasis Type="Italic">Xenopus laevis</Emphasis> (Daudin, 1802), a new exotic amphibian in Portugal

The African clawed frog Xenopus laevis has been introduced at several locations, including Mediterranean climate-type regions. In 2006, several individuals of this species were found inhabiting a stream at Oeiras, about 20 km W of Lisbon, Portugal. Although the place and time of introduction are not clearly identified, there are reasons to believe that this population may be the result of an almost 30-year-old introduction proceeding from research laboratories located nearby. Field surveys were conducted in 2007 and 2008 on the distribution and abundance of this species in the region. The species was found in two streams, about 5 km from each other. While being locally abundant, the adults of X. laevis are smaller than those from South Africa and California. In spite of an abundant production of eggs and tadpoles at one of the streams, no tadpoles were found in advanced developmental stages. Until now, most individuals were found in heavily urbanized areas that should constrain their ability to cross overland to other water bodies. An eradication program may be feasible, but the presence of adults on two streams indicates that the species may be expanding, in spite of the urban landscape.