Positive selection over the mitochondrial genome and its role in the diversification of gentoo penguins in response to adaptation in isolation

Although mitochondrial DNA has been widely used in phylogeography, evidence has emerged that factors such as climate, food availability, and environmental pressures that produce high levels of stress can exert a strong influence on mitochondrial genomes, to the point of promoting the persistence of certain genotypes in order to compensate for the metabolic requirements of the local environment. As recently discovered, the gentoo penguins (Pygoscelis papua) comprise four highly divergent lineages across their distribution spanning the Antarctic and sub-Antarctic regions. Gentoo penguins therefore represent a suitable animal model to study adaptive processes across divergent environments. Based on 62 mitogenomes that we obtained from nine locations spanning all four gentoo penguin lineages, we demonstrated lineage-specific nucleotide substitutions for various genes, but only lineage-specific amino acid replacements for the ND1 and ND5 protein-coding genes. Purifying selection (dN/dS  1) was mostly present in codons of the Complex I (NADH genes), supported by two different codon-based methods at the ND1 and ND4 in the most divergent lineages, the eastern gentoo penguin from Crozet and Marion Islands and the southern gentoo penguin from Antarctica respectively. Additionally, ND5 and ATP6 were under selection in the branches of the phylogeny involving all gentoo penguins except the eastern lineage. Our study suggests that local adaptation of gentoo penguins has emerged as a response to environmental variability promoting the fixation of mitochondrial haplotypes in a non-random manner. Mitogenome adaptation is thus likely to have been associated with gentoo penguin diversification across the Southern Ocean and to have promoted their survival in extreme environments such as Antarctica. Such selective processes on the mitochondrial genome may also be responsible for the discordance detected between nuclear- and mitochondrial-based phylogenies of gentoo penguin lineages

Analysis of current trends in the distribution patterns of ruminant livestock in tropical Africa

This paper attempts to demonstrate the importance of livestock in African Agriculture through an analysis of the major factors affecting livestock density and species composition. In the zonal analysis, the general distribution patterns have been summarised by subdividing the continent into five agro-ecological zones and into four broad geographical regions (west, east, southern and central) following the approach of Jahnke (1982). The livestock population data from his study were given by species and agro-ecological zones for each country, together with estimates of the rural population density based on FAO statistics for the period 1979 to 1981. In the second part of this paper, more recent changes in livestock distribution patterns are examined in order to verify some of the hypotheses formulated and to identify the causes

Nutrient transfers from livestock in West African agricultural systems

The potential supply of nutrients from excreta voided by livestock and what is potentially available for transfer to cropland are examined within a West African context. Nutrient output from cattle is derived from a simulation model that predicts nutrient intake in relation to animal performance and monthly feed supplies; it subsequently links intake to excreted output of lactating and dry cows and young growing stock, as well as of entire cattle herds. The supply side of potential nutrient transfers is addressed at several scales, from agro-ecological zones to that of individual farmers, by analysing rations between livestock and farmed and non-farmed land. At a regional scale, focus is on Nigeria and on the cottonbelt in francophone West Africa. The Nigerian situation elucidates the relationships between livestock and land along the rainfall gradient and brings out the multiple interactions between settled smallholder farmers and more mobile agropastoral and transhumant herders. Farming systems in the cottonbelt demonstrate the importance of animal traction and cash cropping as determinants of nutrient-transfer patterns. At the farm level, three case areas are analysed: two in the cottonbelt of Mali and Cote d'Ivoire and one in the closely settled zone in semi-arid Nigeria. These analyses highlight the variable scenarios of nutrient transfers at the farm and village level, demonstrating that heterogeneity among farmers is as much at play as differences between zones and countries. The implications of these nutrient-transfer scenarios are discussed with emphasis on crop-livestock interactions at increasing levels of population pressure and how they may affect pathways of land-use intensification and soil-fertility maintenance

Prevalência de Echinococcus granulosus (Batsch, 1786) em cães urbanos errantes do município de Dom Pedrito (RS), Brasil Prevalence of Echinococcus granulosus (Batsch, 1786) in urban stray dogs from Dom Pedrito in the State of Rio Grande do Sul, Brazil

Echinococcus granulosus é um dos parasitas mais importantes envolvidos em zoonoses de municípios próximos a fronteira do Rio grande do Sul com a Argentina e Uruguai. Amostras de 65 cães urbanos errantes do município de Dom Pedrito foram analisadas por meio de três técnicas: purgação pelo bromidrato de arecolina para visualização da presença do parasito; ensaio de imunoadsorção enzimática (ELISA), para detecção de coproantígenos, imunofluorescência indireta (IFI), para detecção de anticorpos séricos contra E. granulosus. Destes cães, 7,7% (5/65) apresentaram o parasita nas fezes, 10,8 (7/65) coproantígenos e 13,8% (9/65) anticorpos séricos contra o cestódeo. Conclui-se que a equinococose canina, no meio urbano, pode representar um sério problema à saúde pública, devido ao risco de hidatidose humana.<br>Echinococcus granulosus is the one of the most important parasites involved in zoonosis in the State of Rio Grande do Sul, in cities near the Argentinian and Uruguayian border. Sixty-five samples of urban stray dogs from Dom Pedrito county were analyzed by three techniques: purgation by arecoline hydrobromide, to verify the presence of the parasite; enzyme-linked immunosorbent assay test (ELISA), to detect the coproantigen and indirect immunofluorescence antibody test (IFA) to identify serum antibodies against E. granulosus. From the analyzed dogs 7.7% (5/65) have presented the parasite in feces, 10.8% (7/65) had coproantigens and 13.8% (9/65) serum antibodies against this cestode. It was concluded that canine echinococcosis in the urban zone may represent a serious problem to public health, due to hidatidosis risk for humans