Assessment of species diversity and state of "Stipa tenacissima" steppes

North African steppes are subjected to extreme degradation resulting in the reduction of their surface, genetic erosion of resources, and decrease in biodiversity. "Stipa tenacissima" steppes, which constitute one of the most representative vegetation types in the driest areas of the Mediterranean basin, are continuously degrading. With the aim of contributing to a better knowledge of the floristic composition and diagnosing the state of degradation of these steppes, we conducted a phytoecological analysis of 10 "S. tenacissima" sites in Tunisia. Floristic inventory compiled a systematic list of 46 vascular plant species belonging to 43 genera and 26 families. Species richness ranged from 4 to 18 species per 900 m2. Total vegetation cover was moderate and fluctuated between 22.8% and 49.9%. Our results revealed also a decreasing trend in species richness with increasing elevation (ρ = –0.585). Indeed, species richness was negatively correlated with slope (ρ = –0.19) and positively correlated with sand content (ρ = 0.262). Biological types were dominated by chamaephytes; this chamaephytization is due to the phenomenon of aridization and overgrazing. Moreover, the low species cover and the appearance of nonpalatable species highlighted the vulnerability of these steppes to degradation.

Sensibilizar para a diversidade linguística e cultural no pré-escolar

Relatório de estágio apresentado para obtenção do grau de mestre na especialidade profissional de educação pré-escolar

Estimating the relative roles of top-down and bottom-up forces on insect herbivore populations: A classic study revisited

Although most ecologists agree that both top-down and bottom-up forces (predation and resource limitation, respectively) act in concert to influence populations of herbivores, it has proven difficult to estimate the relative contributions of such forces in terrestrial systems. Using a combination of time–series analysis of population counts recorded over 16 years and experimental data, we present the first estimates of the relative roles of top-down and bottom-up forces on the population dynamics of two terrestrial insect herbivores on the English oak (Quercus robur). Data suggest that temporal variation in winter moth, Operophtera brumata, density is dominated by time-lagged effects of pupal predators. By comparison, spatial variation in O. brumata density is dominated by host–plant quality. Overall, top-down forces explain 34.2% of population variance, bottom-up forces explain 17.2% of population variance, and 48.6% remains unexplained. In contrast, populations of the green oak tortrix, Tortrix viridana, appear dominated by bottom-up forces. Resource limitation, expressed as intraspecific competition among larvae for oak leaves, explains 29.4% of population variance. Host quality effects explain an additional 5.7% of population variance. We detected no major top-down effects on T. viridana populations. An unknown factor causing a linear decline in T. viridana populations over the 16-year study period accounts for most of the remaining unexplained variance. We discuss the observed differences between the insect species and the utility of time–series analysis as a tool in assessing the relative importance of top-down and bottom-up forces on herbivore populations.

The diversity and evolutionary relationships of the pregnancy-associated glycoproteins, an aspartic proteinase subfamily consisting of many trophoblast-expressed genes

The pregnancy-associated glycoproteins (PAGs) are structurally related to the pepsins, thought to be restricted to the hooved (ungulate) mammals and characterized by being expressed specifically in the outer epithelial cell layer (chorion/trophectoderm) of the placenta. At least some PAGs are catalytically inactive as proteinases, although each appears to possess a cleft capable of binding peptides. By cloning expressed genes from ovine and bovine placental cDNA libraries, by Southern genomic blotting, by screening genomic libraries, and by using PCR to amplify portions of PAG genes from genomic DNA, we estimate that cattle, sheep, and most probably all ruminant Artiodactyla possess many, possibly 100 or more, PAG genes, many of which are placentally expressed. The PAGs are highly diverse in sequence, with regions of hypervariability confined largely to surface-exposed loops. Nonsynonymous (replacement) mutations in the regions of the genes coding for these hypervariable loop segments have accumulated at a higher rate than synonymous (silent) mutations. Construction of distance phylograms, based on comparisons of PAG and related aspartic proteinase amino acid sequences, suggests that much diversification of the PAG genes occurred after the divergence of the Artiodactyla and Perissodactyla, but that at least one gene is represented outside the hooved species. The results also suggest that positive selection of duplicated genes has acted to provide considerable functional diversity among the PAGs, whose presence at the interface between the placenta and endometrium and in the maternal circulation indicates involvement in fetal–maternal interactions.

Inverse radiation dose-rate effects on somatic and germ-line mutations and DNA damage rates

The mutagenic effect of low linear energy transfer ionizing radiation is reduced for a given dose as the dose rate (DR) is reduced to a low level, a phenomenon known as the direct DR effect. Our reanalysis of published data shows that for both somatic and germ-line mutations there is an opposite, inverse DR effect, with reduction from low to very low DR, the overall dependence of induced mutations being parabolically related to DR, with a minimum in the range of 0.1 to 1.0 cGy/min (rule 1). This general pattern can be attributed to an optimal induction of error-free DNA repair in a DR region of minimal mutability (MMDR region). The diminished activation of repair at very low DRs may reflect a low ratio of induced (“signal”) to spontaneous background DNA damage (“noise”). Because two common DNA lesions, 8-oxoguanine and thymine glycol, were already known to activate repair in irradiated mammalian cells, we estimated how their rates of production are altered upon radiation exposure in the MMDR region. For these and other abundant lesions (abasic sites and single-strand breaks), the DNA damage rate increment in the MMDR region is in the range of 10% to 100% (rule 2). These estimates suggest a genetically programmed optimatization of response to radiation in the MMDR region.

Diversity and phylogeny of gephyrin: Tissue-specific splice variants, gene structure, and sequence similarities to molybdenum cofactor-synthesizing and cytoskeleton-associated proteins

Gephyrin is essential for both the postsynaptic localization of inhibitory neurotransmitter receptors in the central nervous system and the biosynthesis of the molybdenum cofactor (Moco) in different peripheral organs. Several alternatively spliced gephyrin transcripts have been identified in rat brain that differ in their 5′ coding regions. Here, we describe gephyrin splice variants that are differentially expressed in non-neuronal tissues and different regions of the adult mouse brain. Analysis of the murine gephyrin gene indicates a highly mosaic organization, with eight of its 29 exons corresponding to the alternatively spliced regions identified by cDNA sequencing. The N- and C-terminal domains of gephyrin encoded by exons 3–7 and 16–29, respectively, display sequence similarities to bacterial, invertebrate, and plant proteins involved in Moco biosynthesis, whereas the central exons 8, 13, and 14 encode motifs that may mediate oligomerization and tubulin binding. Our data are consistent with gephyrin having evolved from a Moco biosynthetic protein by insertion of protein interaction sequences.

Human-caused environmental change: Impacts on plant diversity and evolution

Human-caused environmental changes are creating regional combinations of environmental conditions that, within the next 50 to 100 years, may fall outside the envelope within which many of the terrestrial plants of a region evolved. These environmental modifications might become a greater cause of global species extinction than direct habitat destruction. The environmental constraints undergoing human modification include levels of soil nitrogen, phosphorus, calcium and pH, atmospheric CO2, herbivore, pathogen, and predator densities, disturbance regimes, and climate. Extinction would occur because the physiologies, morphologies, and life histories of plants limit each species to being a superior competitor for a particular combination of environmental constraints. Changes in these constraints would favor a few species that would competitively displace many other species from a region. In the long-term, the “weedy” taxa that became the dominants of the novel conditions imposed by global change should become the progenitors of a series of new species that are progressively less weedy and better adapted to the new conditions. The relative importance of evolutionary versus community ecology responses to global environmental change would depend on the extent of regional and local recruitment limitation, and on whether the suite of human-imposed constraints were novel just regionally or on continental or global scales.

Genetic diversity and susceptibility to Vip3Aa20 protein in Brazilian populations of Helicoverpa armigera and Helicoverpa zea (Lepidoptera: Noctuidae)

Helicoverpa armigera (Hübner) was officially reported in Brazil in 2013. This species is closely related to Helicoverpa zea (Boddie) and has caused significant crop damage in Brazil. The use of genetically modified crops expressing insecticidal protein from Bacillus thuringiensis (Berliner) has been one of the control tactics for managing these pests. Genetically modified maize expressing Vip3Aa20 was approved to commercial use in Brazil in 2009. Understanding the genetic diversity and the susceptibility to B. thuringiensis proteins in H. armigera and H. zea populations in Brazil are crucial for establishing Insect Resistance Management (IRM) programs in Brazil. Therefore, the objectives of this study were: (a) to infer demographic parameters and genetic structure of H. armigera and H. zea Brazil; (b) to assess the intra and interspecific gene flow and genetic diversity of H. armigera and H. zea; and (c) to evaluate the susceptibility to Vip3Aa20 protein in H. armigera and H. zea populations of Brazil. A phylogeographic analysis of field H. armigera and H. zea populations was performed using a partial sequence data from the cytochrome c oxidase I (COI) gene. H. armigera individuals were most prevalent on dicotyledonous hosts and H. zea individuals were most prevalent on maize crops. Both species showed signs of demographic expansion and no genetic structure. High genetic diversity and wide distribution were observed for H. armigera. A joint analysis indicated the presence of Chinese, Indian, and European lineages within the Brazilian populations of H. armigera. In the cross-species amplification study, seven microsatellite loci were amplified; and showed a potential hybrid offspring in natural conditions. Interespecific analyses using the same microsatellite loci with Brazilian H. armigera and H. zea in compare to the USA H. zea were also conducted. When analyses were performed within each species, 10 microsatellites were used for H. armigera, and eight for H. zea. We detected high intraspecific gene flow in populations of H. armigera and H. zea from Brazil and H. zea from the USA. Genetic diversity was similar for both species. However, H. armigera was more similar to H. zea from Brazil than H. zea from the USA and some putative hybrid individuals were found in Brazilian populations.Tthere was low gene flow between Brazilian and USA H. zea. The baseline susceptibility to Vip3Aa20 resulted in low interpopulation variation for H. zea (3-fold) and for H. armigera (5-fold), based on LC50. H. armigera was more tolerant to Vip3Aa20 than H. zea (≈ 40 to 75-fold, based on CL50). The diagnostic concentration for susceptibility monitoring, based on CL99, was fairly high (6,400 ng Vip3Aa20/cm2) for H. zea and not validated for H. armigera due to the high amount of protein needed for bioassays. Implementing IRM strategies to Vip3Aa20 in H. armigera and H. zea will be of a great challenge in Brazil, mainly due to the low susceptibility to Vip3Aa20 and high genetic diversity and gene flow in both species, besides a potential of hybrid individuals between H. armigera and H. zea under field conditions.

Environmental health, indigenous identity, cultural representations and the production of ecological consciousness in Northern Ontario

The primary goal of this research is to document local perspectives by presenting a set of commentaries and meanings, in the form of narratives, related to environmental health conceptions on an Oji-Cree reserve in Northeastern Ontario, Canada. Through an ethnographic case study, this research explores how the modern-day production of a sociocentric and ecocentric self, as ethnic marker and moral category, is contributing to environmental/community health and well-being on Native reserves. Cultural representations of personhood and community based on the Medicine Wheel model, as a cognitive model, create an ontological paradigm that promotes a holistic foundation for human behaviour and interaction, as well as healthy, sustainable communities.

Chemical diversity and potential biological functions of the pygidial gland secretions in two species of Neotropical dung roller beetles

Dung roller beetles of the genus Canthon (Coleoptera: Scarabaeinae) emit an odorous secretion from a pair of pygidial glands. To investigate the chemical composition of these secretions, we used stir bar sorptive extraction (SBSE), coupled with gas chromatography–mass spectrometry (GC–MS) for analysis of extracts of pygidial gland secretions secreted by the dung roller beetles Canthon femoralis femoralis and Canthon cyanellus cyanellus. Chemical analyses of volatiles collected from pygidial gland secretions comprise a great diversity of the functional groups. Chemical profile comparisons showed high intra- and interspecific variability. The pygidial gland secretion of Canthon f. femoralis was dominated by sesquiterpene hydrocarbons, whereas the profile of Canthon c. cyanellus was dominated by carboxylic acids. The different pygidial secretions have a high diversity of chemical compounds suggesting a multifunctional nature involving some key functions in the biology. We discuss the biological potential of these compounds found in the pygidial glands of each species with respect to their ecological and behavioral relevance.

Mogollon cultural continuity and change; the stratigraphic analysis of Tularosa and Cordova Caves / [by] Paul S. Martin, Chief Curator, Department of Anthropology, et al.

v.40(1952)

The Dynamics of Decentralization in Italy: Towards a Federal Solution? European Diversity and Autonomy Papers, EDAP/04 2013

This paper analyses the recent process of state decentralisation in Italy from the perspectives of political science and constitutional law. It considers the conflicting pressures and partisan opportunism of the decentralising process, and how these have adversely affected the consistency and completeness of the new constitutional framework. The paper evaluates the major institutional reforms affecting state decentralisation, including the 2001 constitutional reform and the more recent legislation on fiscal federalism. It argues that while the legal framework for decentralisation remains unclear and contradictory in parts, the Constitutional Court has performed a key role in interpreting the provisions and giving life to the decentralised system, in which regional governments now perform a much more prominent role. This new system of more decentralised multi-level government must nevertheless contend with a political culture and party system that remains highly centralised, while the administrative apparatus has undergone no comparable shift to take account of state decentralisation, leading to the duplication of bureaucracy at all territorial levels and continuing conflicts over policy jurisdiction. Unlike in federal systems these conflicts cannot be resolved in Italy through mechanisms of “shared rule”, since formal inter-governmental coordination structure are weak and entirely consultative.