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Horizontal gene transfer (HGT) is widespread among prokaryotes driving their evolution. In this paper, we review the potential impact in humans of the HGT between prokaryotes living in close association with humans in two scenarios: horizontal transfer in human microbiomes and transfer between microbes living in human managed environments. Although our vision is focused on the possible impact of these transfers in the propagation of antibiotic resistance genes or pathogenicity determinants, we also discuss possible human physiological adaptations via gene transfer between resident and occasional bacteria in the human microbiome. [ABSTRACT FROM AUTHOR]

Horizontal gene transfer has, over the past 25 years, become a part of evolutionary thinking. In the present paper I discuss horizontal gene transfer (HGT) in relation to contingency, natural selection, evolutionary change speed and the Tree-of-Life endeavour, with the aim of contributing to the understanding of the role of HGT in evolutionary processes. In addition, the challenges that HGT imposes on the current view of evolution are emphasized. [ABSTRACT FROM AUTHOR]

The author discusses science and religion. He states that scientific knowledge is a set of theories and data obtained through experiments. Scientist Charles Darwin once stated that there is no good and original observation and careful attention paid to experiments leads to advancement of knowledge. Personal beliefs can be followed but should be kept out of lab in scientific experiments.

Studies on the experimental evolution of microorganisms, on their in vivo evolution (mainly in the case of bacteria producing chronic infections), as well as the availability of multiple full genomic sequences, are placing bacteria in the playground of evolutionary studies. In the present article we review the differential contribution to the evolution of bacterial genomes that processes such as gene modification, gene acquisition and gene loss may have when bacteria colonize different habitats that present characteristic ecological features. In particular, we review how the different processes contribute to evolution in microbial communities, in free-living bacteria or in bacteria living in isolation. In addition, we discuss the temporal constraints in the evolution of bacterial genomes, considering bacterial evolution from the perspective of processes of short-sighted evolution and punctual acquisition of evolutionary novelties followed by long stasis periods. [ABSTRACT FROM AUTHOR]

Three recent papers underline the importance of the host genomic background in allowing the stable maintenance of horizontally acquired genes. These studies suggest that post-transfer changes in both host genome and acquired genes contribute to the stable integration of foreign genes. [ABSTRACT FROM AUTHOR]

Darwin’s main contribution to modern biology was to make clear that all history of life on earth is dominated by a simple principle, which is usually summarised as 'descent with modification'. However, interpretations about how this modification is produced have been controversial. In light of the data provided by recent studies on molecular biology, developmental biology, genomics, and other biological disciplines we discuss, in this paper, how Darwin's theory may apply to two main 'types' of evolution: that occurring in the prebiotic world and that regarding the acquisition of major key-innovations differentiating higher-taxa, which makes up part of the so-called macroevolution. We argue that these studies show that evolution is a fascinating, complex and multifaceted process, with different mechanisms drivin it on different occasions and in different places. [ABSTRACT FROM AUTHOR]

The Mesa Central of Mexico is of special conservation interest due to its high richness of freshwater fish species, of which the goodeines are one of the most representative groups. Through an integrated approach, we determined conservation priorities for goodeine populations. We based our recommendations on the genetic diversity (variation in five microsatellite DNA loci) in 10 populations of Zoogoneticus quitzeoensis and on an analysis of ecological (e.g., presence of exotic species), social (e.g., political situation), and environmental (e.g., pollution) information for 52 historical occurrence points for species in the genus Zoogoneticus . Patterns of genetic erosion and genetic diversity indices were closely associated with human impact. Recent bottleneck events were most evident in the populations from remnants of the lakes drained at the beginning of the twentieth century. We identified seven operational conservation units (OCUs), all of which should be conserved because they contain unique portions of the total variation of the species. Special attention needs to be given to increase genetic variability, recover population sizes, and reestablish contact among populations within OCUs. It is imperative to create an integrative and effective approach for the recovery and conservation of the freshwater fish diversity of Central Mexico that is based on social and natural sciences. [ABSTRACT FROM AUTHOR]

The importance that the density of breeders has on the opportunity for extra-pair fertilizations (EPFs) is controversial. Some evidence supports the idea that population density and frequency of extra-pair paternity are positively associated, whereas other work does not. In the present paper we estimate EPF frequency in a dense House Sparrow Passer domesticus colony. We detected extra-pair nestlings in 9.3% of 54 broods studied, and 7% of 171 nestlings were sired by extra-pair fathers. The number of clutches laid per female, the change of male or female between two consecutive breeding attempts and the age of the partners showed no association with the presence or absence of extra-pair fertilizations. Morphometric variables of paired males and females did not discriminate broods with EPFs from those without. We detected a single case of a female laying a "parasitic" egg in the nest of a male that in a previous breeding attempt was the extra-pair genetic father of her entire brood. The frequency of extra-pair fertilization recorded in this study was low compared with that in other House Sparrow populations breeding at lower densities, or other species that breed in colonies. This result does not support the claim that EPF frequency is associated with population density. We propose, as an explanation for this result, that under high intra-sexual competition for nest sites (1) males may have limited opportunities to search for females for extra-pair copulations and (2) the high quality of male nest-owners may reduce female propensity to search for additional sexual partners. [ABSTRACT FROM AUTHOR]

Horizontal gene transfer is accepted as an important evolutionary force modulating the evolution of prokaryote genomes. However, it is thought that horizontal gene transfer plays only a minor role in metazoan evolution. In this paper, I critically review the rising evidence on horizontally transferred genes and on the acquisition of novel traits in metazoans. In particular, I discuss suspected examples in sponges, cnidarians, rotifers, nematodes, molluscs and arthropods which suggest that horizontal gene transfer in metazoans is not simply a curiosity. In addition, I stress the scarcity of studies in vertebrates and other animal groups and the importance of forthcoming studies to understand the importance and extent of horizontal gene transfer in animals. [ABSTRACT FROM AUTHOR]

The occurrence of fructose 2,6-bisphosphate was detected in Dictyostelium discoideum. The levels of this compound were compared with those of cyclic AMP and several glycolytic intermediates during the early stages of development. Removal of the growth medium and resuspension of the organism in the differentiation medium decreased the content of fructose 2,6-bisphosphate to about 20% within 1 h, remaining low when starvation-induced development was fallowed for 8 h. The content of cyclic AMP exhibited a transient increase that did not correlate with the change in fructose 2,6-bisphosphate. If after 1 h of development 2% glucose was added to the differentiation medium, fructose 2,6-bisphosphate rapidly rose to similar levels to those found in the vegetative state, while the increase in cyclic AMP was prevented. The contents of hexose 6-phosphates, fructose 1,6-bisphosphate and those phosphates changed in a way that was parallel to that of fructose 2,6-bisphosphate, and addition of sugar resulted in a large increase in the levels of these metabolites. The content of fructose 2,6-bisphosphate was not significantly modified by the addition of the 8-bromo or dibutyryl derivatives of cyclic AMP to the differentiation medium. These results provide evidence that the changes in fructose 2,6-bisphosphate levels in D. discoideum development are not related to a cyclic-AMP-dependent mechanism but to the availability of substrate. Fructose 2,6-bisphosphate was found to inhibit fructose-1,6-bisphosphatase activity of this organism at nanomolar concentrations, while it does not affect the activity of phosphofructokinase in the micromolar range. The possible physiological implications of these phenomena are discussed. [ABSTRACT FROM AUTHOR]