Complete Genome Viral Phylogenies Suggests the Concerted Evolution of Regulatory Cores and Accessory Satellites

We consider the concerted evolution of viral genomes in four families of DNA viruses. Given the high rate of horizontal gene transfer among viruses and their hosts, it is an open question as to how representative particular genes are of the evolutionary history of the complete genome. To address the concerted evolution of viral genes, we compared genomic evolution across four distinct, extant viral families. For all four viral families we constructed DNA-dependent DNA polymerase-based (DdDp) phylogenies and in addition, whole genome sequence, as quantitative descriptions of inter-genome relationships. We found that the history of the polymerase gene was highly predictive of the history of the genome as a whole, which we explain in terms of repeated, co-divergence events of the core DdDp gene accompanied by a number of satellite, accessory genetic loci. We also found that the rate of gene gain in baculovirus and poxviruses proceeds significantly more quickly than the rate of gene loss and that there is convergent acquisition of satellite functions promoting contextual adaptation when distinct viral families infect related hosts. The congruence of the genome and polymerase trees suggests that a large set of viral genes, including polymerase, derive from a phylogenetically conserved core of genes of host origin, secondarily reinforced by gene acquisition from common hosts or co-infecting viruses within the host. A single viral genome can be thought of as a mutualistic network, with the core genes acting as an effective host and the satellite genes as effective symbionts. Larger virus genomes show a greater departure from linkage equilibrium between core and satellites functions

Financial credit drives urban land-use change in the United States

Land-use change in the United States is a significant factor in environmental degradation, and occurs at a faster rate than population growth. This paper develops the hypothesis that modern financial instruments and the creation of tools that increase reliance on debt have the undesirable consequences of run-away land-use change, particularly in residential home construction. After reviewing the factors leading to increased housing development and land use change, the paper elucidates the role of modern financial instruments in driving rapid land conversion. The theory is based upon accounting of sources and uses of capital. Financial innovations, especially in credit creation and trading through global capital markets, can help explain the link between land-use change and finance. Available data from a study of modern real estate development supports the role of financial debt as the primary driver for land use change in South Florida. The mechanisms behind development financing address key policies and practices that have led to unsustainable land cover change. We encourage work on land-use change that focuses on a better understanding of the mechanisms linking land developers to financial markets, and cross-disciplinary research that recognizes linkages between financial innovations and ecological health, and that leads to the development of better policies