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Morphological variation of the skull was examined in the northern treeshrew (Tupaia belangeri) from various localities across Southeast Asia. Through a multivariate analysis, the treeshrews from South Vietnam exhibited distinct morphological characteristics compared to other populations from Thailand and Laos, and Malaysia. The plots of the specimens of North Vietnam are not randomly mixed with Thailand plots segregation in the scatteregrams of canonical discriminant analysis. Since the skulls of the population from North Vietnam were morphologically similar to those form central Laos and northern and northeastern Thailand, the zoogeographical barrier effect of Mekong River was not clearly confirmed. The population of the Kanchanaburi in western Thailand is clearly smaller in size compared to the other populations. The southern border of the distribution of this species is determined by the Isthmus of Kra or Kangar-Pattani Line. In the northern treeshrew, which is distributed from southern China to Bangladesh and southern Thailand, we have detected osteometrical geographical variation driven by geography. These results indicate that the skull morphology in the Tupaia glis-belangeri complex distinctively differs in South Vietnam, western Thailand, and southern Thailand. The zoogeographical barrier and factor separating these districts are expected to clarify in the future.

The global road network is rapidly growing associated with human economic development. This growth also entails a high toll for biodiversity, with several well-documented negative impacts on different species. However, there is still a great lack of knowledge about the effects of roads on the persistence of wildlife populations. Here, we aimed to summarize our current knowledge on this topic, based on systematic reviews. We found that only a small proportion of studies (8%) focused on the effects of roads on population persistence. Most of these studies were about large mammals and were performed in high-income countries. Furthermore, these works studied only 2% of those species identified by the IUCN Red List as threatened by roads. Overall, our results show that we are far from understanding how roads affect the long-term viability of wildlife populations inhabiting road-effect zones. Addressing this challenge will require modifying our conceptual perspective, from short-term to long-term studies, from single road sections to focusing the landscape scale, and strive to obtain empirical data to support sound analyses to assess how road impacts affect the survival of wildlife populations, namely with information required to perform approaches such as population viability analyses. We highlight some key studies from our reviews that have addressed this global conservation concern with population-oriented approaches.

Globally, the aggregate length of roads exceeds 64 million km and 90.7% of protected areas are disturbed by road penetration, and therefore understanding how road networks impact species and ecosystem processes is highly relevant to applied conservation ecology. Among various effects on wildlife, roads may disrupt the interaction between plants and their animal-mediated seed dispersers, compromising forest regeneration and composition. Here, using the acorn-rodent system, we quantified to what extent rodent functions on seed dispersal are modified by roads over two years (i.e. 2013 and 2014). Road had negative effects on seed-dispersal services provided by rodents, with an approximate 30% reduction of seed dispersal effectiveness (SDE) and 50% reductions of dispersal distance in proximity to the road. These detrimental effects gradually declined along a gradient from the roadside towards forest interior. Declines of rodent abundance in proximity to the road seem to induce these depressed seed dispersal functions. Although the influential magnitudes of roads on SDE were similar in both years, its influential magnitudes on seed dispersal were stronger in 2014 which indicates the more negative impacts of road encroachment on seed dispersal services. Crucially, no tagged seeds were dispersed across the road, implying that it imposed a barrier effect on animal-mediated seed dispersal and plant recruitment. Given wildlife’s key roles in plant recruitment, we conclude that the ever-expanding effect of roads on animal-mediated seed dispersal may ultimately cause profound changes in forest composition and structure across diverse ecosystems, on a global scale.

Advances in spectral-domain optical coherence tomography (SD-OCT) technology have enhanced the understanding of external limiting membrane (ELM) and ellipsoid zone (EZ) in diabetic macular edema. An increase in VEGF has been demonstrated to be associated with sequential ELM and EZ disruption on SD-OCT. An intact ELM is a prerequisite for an intact EZ in DME. Anti-VEGF therapy leads to restoration of barrier effect of ELM. The ELM restores first followed by EZ restoration.

The ocular surface flora perform an important role in the defense mechanisms of the ocular surface system. Its regulation of the immunological activity and the barrier effect against pathogen invasion are remarkable. Composition of the flora differs according to the methods of investigation, because the microbiome, composed of the genetic material of bacteria, fungi, viruses, protozoa, and eukaryotes on the ocular surface, differs from the microbiota, which are the community of microorganisms that colonize the ocular surface. The observed composition of the ocular surface flora depends on harvesting and examining methods, whether with traditional culture or with more refined genetic analysis based on rRNA and DNA sequencing. Environment, diet, sex, and age influence the microbial flora composition, thus complicating the analysis of the baseline status. Moreover, potentially pathogenic organisms can affect its composition, as do various disorders, including chronic inflammation, and therapies applied to the ocular surface. A better understanding of the composition and function of microbial communities at the ocular surface could bring new insights and clarify the epidemiology and pathology of ocular surface dynamics in health and disease. The purpose of this review is to provide an up-to-date overview of knowledge about this topic.

The objective of this study was to investigate the effect of spices and packaging films on the bacterial dynamics of pot-stewed duck wings (PSDW) during storage at 8°C. The results showed that spices added at a 1 : 1 ratio (weight ratio of pungent spices and fragrant spices) could delay the lag period of bacterial growth and extend the shelf-life of PSDW. Denaturing Gel Gradient Electrophoresis (DGGE) analysis indicated that the predominant bacteria in PSDW at the end of storage were Weisella hellenica, Weisella diestrammenae, Staphylococcus equorum and Streptococcus parauberis, and spices added at a 1 : 1 ratio showed better inhibition for bacteria at the end of storage, except for W. hellenica. Thus, general-purpose and high barrier films in modified atmosphere packaging, had a good barrier effect for the isolation of air, and showed no effect on the bacteria. This study will help PSDW processing companies to understand the biodiversity of PSDW, and provide a scientific basis for the extension of shelf-life. Significance and Impact of the Study This study confirmed that high barrier cover film, general barrier base film and spices added at a 1 : 1 ratio (weight ratio of pungent and fragrant spices), had a better inhibition effect on bacteria in pot-stewed duck wings products, which could be used for processing and storage conditions of this product. Simultaneously, the change in the bacterial community of this product during 8°C storage was analysed, where the predominant bacteria of modified atmosphere packaging pot-stewed duck wings at the end of 8°C storage included Weisella hellenica, Weisella diestrammenae, Staphylococcus equorum and Streptococcus parauberis.

Roads have a pervasive multi-faceted influence on ecosystems, including pronounced impacts on wildlife movements. In recognition of the scale-transcending impacts of transportation infrastructure, ecologists have been encouraged to extend the study of barrier impacts from individual roads and animals to networks and populations. In this study, we adopt an analytical representation of road networks as mosaics of landscape tiles, separated by roads. We then adapt spatial capture-recapture analysis to estimate the propensity of wildlife to stay within the boundaries of the road network tiles (RNTs) that hold their activity centres. We fit the model to national non-invasive genetic monitoring data for brown bears (Ursus arctos) in Sweden and show that bears had up to 73% lower odds of using areas outside the network tile of their home range centre, even after accounting for the effect of natural barriers (major rivers) and the decrease in utilization with increasing distance from a bear’s activity centre. Our study highlights the pronounced landscape-level barrier effect on wildlife mobility and, in doing so, introduces a novel and flexible approach for quantifying contemporary fragmentation from the scale of RNTs and individual animals to transportation networks and populations. non-invasive genetic sampling, road network tile, island biogeography, road ecology, spatial capture-recapture, fragmentation, carnivores, transportation network

The gut is an enormously complex environment in which microbiota, nutrients, and host cells interact widely, a process significant for the gut homeostasis and host health. Gut microbial organization plays many roles in the host body, including metabolic, barrier effect, and trophic functions. Many diseases have henceforth been connected to gut microbiota impairment. This part provides in depth view of the close relationships between gut microbiota, host health, and disease.

Chromatin remodelers are essential for establishing and maintaining the placement of nucleosomes along genomic DNA. Yet how chromatin remodelers recognize and respond to distinct chromatin environments surrounding nucleosomes is poorly understood. Here, we use Lac repressor as a tool to probe how a DNA-bound factor influences action of the Chd1 remodeler. We show that Chd1 preferentially shifts nucleosomes away from Lac repressor, demonstrating that a DNA-bound factor defines a barrier for nucleosome positioning. Rather than an absolute block in sliding, the barrier effect was achieved by altered rates of nucleosome sliding that biased redistribution of nucleosomes away from the bound Lac repressor site. Remarkably, in addition to slower sliding toward the LacO site, the presence of Lac repressor also stimulated sliding in the opposite direction. These experiments therefore demonstrate that Chd1 responds to the presence of a bound protein on both entry and exit sides of the nucleosome. This sensitivity to both sides of the nucleosome allows for a faster and sharper response than would be possible by responding to only the entry side, and we speculate that dual entry/exit sensitivity is also important for regularly spaced nucleosome arrays generated by Chd1 and the related ISWI remodelers.

The role of polyamines of the human Lactobacillus plantarum strain Inducia (DSM 21379) for modulation of innate immune markers was explored. The strains’ genes for polyamines, and amino acid metabolites were tested. Edam-type cheese comprised with putrescine producing strain Inducia, and control cheese were administered to n = 20 NIH-line mice and tested in 12 healthy Estonian volunteers (ISRCTN38739209) consuming 50 g Inducia cheese (3 × 109 CFU/daily) and control cheese in blinded placebo-controlled 3-week cross-over trial In experimental mice the amount of ileal and colonic lymphatic tissue, the count and diversity of lactobacilli increased. In volunteers' urine acetylated putrescine (p = 0.021); monocytes (p = 0.032), and cytokine IL-6 (p = 0.020) content in blood increased moderately. The amount of putrescine with IL-6 (r = 0.892, p = 0.003); acetylated spermidine with monocytes (r = 0.657, p = 0.039) and high-sensitive C-reactive protein (r = 0.848, p = 0.004) were correlated. Polyamines of L. plantarum Inducia and its food products can enhance the innate immune markers.

The modern human gut is teeming with bacterial cells, mostly located in the colon: about 100 trillion cells in total, representing more than 1,000 species of bacteria. By shaping and maintaining normal mucosal immunity, the intestinal flora forms a “barrier effect” that prevents colonization of the intestine by pathogens and thereby helps the body defend against infections. The delicate balance between microbes can be disturbed by diet, alcohol, contaminated foods, antibiotics, stress, and aging, as well as by digestive disorders and diseases. There is a growing market for foods that contain probiotic bacteria, and a wide variety of probiotic strains are being added to an array of foods. The ability of probiotic strains to survive conditions encountered in industrial manufacturing processes (e.g., temperature, pH, oxygen, etc.) is the main obstacle food manufacturers must overcome. For example, the heat involved in baking can result in significant losses in probiotic viability during the manufacture and s...

Reindeer herdsmen and authorities in Scandinavia fear detrimental effects from wind-power plants (WPs) on movements and area use of reindeer Rangifer tarandus tarandus. We tested the extent to which a WP represented a behavioural barrier for reindeer movement by comparing two neighbouring areas; one peninsula with and one without a WP. Both peninsulas had a parallel road and a power line bisecting them in a north-south direction. Presence of a larger or similar number of reindeer on the outer western compared to the inner eastern sections in both areas indicated no barrier effect from the WP. Furthermore, no clear barrier effects were found for reindeer movements during summer in the WP or neighbouring area, as reindeer have continued to cross back and forth between the inner and outer sections of the two areas. Contrary to our expectation, our finding contrasted with previous studies finding negative barrier effects from linear structures such as power lines and roads, suggesting considerable variation i...

Wire fences are widely used in rangelands around the world and may have a negative impact on wildlife that varies among species and habitats. The guanaco (Lama guanicoe) is the largest Patagonian ungulate and though entanglement in wire fences is frequently reported, its impact on guanaco populations has not been previously evaluated. We estimated annual mortality rate of wild guanacos due to entanglement in wire fences and evaluated whether the frequency of entanglement was age-dependent in the two wire-fence designs traditionally used in Patagonian sheep ranches. We found that annual yearling mortality on fences (5.53%) was higher than adult mortality (0.84%) and was more frequent in ovine (93. cm high) than bovine (113. cm) fences. Most guanacos died entangled by their legs in the highest wire when trying to jump over the fence. Our results suggest that guanacos are more likely to die due to fence entanglement than ungulates studied in other regions. Indirect effects of wire fences should also be considered as they may act as semi-permeable barriers for guanaco populations. We suggest removal of unnecessary wire fences and replacement by guanaco-friendly fences, like high-tensile electric fences that may reduce mortality and barrier-effect on guanaco populations. Fil: Rey, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Novaro, Andres Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Wildlife Conservation Society; Estados Unidos Fil: Guichon, Maria Laura. Universidad Nacional de Luján. Departamento de Ciencias Básicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Previous studies suggest the gap in forest cover generated by roads contributes to the barrier effect of roads on movement of forest-dwelling small mammals. However, it is not known if vegetated medians of divided highways affect movement of small mammals by reducing the effective highway width. The purpose of our study was to determine whether the type of vegetation cover in the median (treed or grassy) or median width affects small-mammal crossings of divided highways. At 11 study sites varying in median cover type and width, we live-trapped small mammals next to one side of the highway and translocated them to the opposite side of the highway using a standardized translocation distance. In total, 24% of translocated individuals were recaptured on the side of the highway of initial capture, i.e., they had moved across the entire highway. This was significantly lower than what would have been expected in the absence of the highway (58%). The overall probability of recapturing a translocated individual was not significantly related to median cover type or width. Our results suggest that efforts to mitigate the barrier effect of highways on small mammals cannot be accomplished by al- tering median vegetation type and width. Resume : Des etudes anterieures laissent croire que les trouees dans la couverture forestiere formees par les routes contri- buent a l'effet de barriere des routes sur les deplacements des petits mammiferes forestiers. On ne sait pas, cependant, si des terre-pleins centraux de vegetation dans les routes divisees affectent les deplacements des petits mammiferes en reduisant la largeur effective des grandes routes. Le but de notre etude est de determiner si le type de couverture vegetale (arborescent ou herbeux) et la largeur du terre-plein central affectent la traversee des routes divisees par les petits mammiferes. A 11 sites d'etude presentant une variete de types de couverture et de largeurs du terre-plein central, nous avons piege des petits mam- miferes vivants pres d'un cote de la grande route et les avons relocalises sur le cote oppose a une distance standardisee de deplacement. En tout, 24 % des individus deplaces ont ete recaptures du cote de leur capture originale, c.-a-d. qu'ils ont tra- verse toute la route. C'est un pourcentage significativement plus bas que celui attendu en l'absence de grande route (58 %). La probabilite globale de recapturer un individu deplace n'est pas reliee significativement au type de couverture, ni a la lar- geur du terre-plein central. Nos resultats font penser que les efforts de mitigation de l'effet de barriere des grandes routes sur les petits mammiferes ne peuvent consister en une modification du type de vegetation et de la largeur des terre-pleins centraux. (Traduit par la Redaction)

Highways constitute barriers to wildlife passage, or permeability, which fragment populations and habitats. The degree of barrier effect caused by roadways varies by wildlife species, highway type and standard, and traffic volume. We assessed deer–highway relationships along a 27-km stretch of highway in central Arizona, USA. Our research objectives were to 1) assess white-tailed deer (Odocoileus virginianus) highway crossing patterns and permeability, 2) compare deer permeability on 4-lane reconstructed and 2-lane control sections to determine the influence of wildlife underpasses, and 3) assess and compare deer passage relationships to traffic volume. We fitted 13 deer with Global Positioning System (GPS) collars between 2004 and 2007. Eleven deer crossed the highway 395 times. On 2 control sections, deer crossed an average of 0.02 times/day, while on 3 reconstructed sections they averaged 15 times more crossings/day (0.28; t13 = −2.35; P = 0.035). The deer passage rate on control sections averaged 0.03 crossings/approach, approximately 20% of that for reconstructed sections (0.16; t13 = −2.43; P = 0.030). We linked hourly traffic volumes to our GPS data to examine how passage rates and the proportion of deer relocations at different distances from the highway varied with traffic volume. Deer distance from the highway showed minimal shift away from the highway with increased traffic, and at-grade passage rates were low (≤0.1 crossings/approach) across all traffic volumes. Although our linear regression analysis found no relationship between deer passage rate and increasing traffic volume on reconstructed sections with underpasses, there was a strong negative relationship on control sections (r = −0.881; P = 0.05); thus, we conclude that deer passage rates were minimally affected by traffic on reconstructed sections where passage structures facilitated below-grade passage. Further, from the 865 deer groups we recorded on videotape at 5 underpasses, traffic levels did not affect below-grade deer passage at the volumes we studied. Passage structures improved highway permeability across reconstructed sections with underpasses where traffic volume had a much lower impact compared to deer crossing at highway grade on control sections. © 2011 The Wildlife Society.

This study reviewed recent studies of road-kill, barrier effect and mitigation techniques on wild animals. It also surveyed road-crossing structures used in Japan. By comparing Japanese and international case studies, we addressed the possibility of studies on road-kill, barrier effect and mitigation technique development in Japan. The road-studies in Japan were mostly studies of the road-kill of Sika deer, Cervus nippon yesoensis, and Raccoon dog, Nyctereutes procyonoides. There were fewer Japanese studies on roadkill and barrier effect examining species, taxa, and landscapes than international studies. Most of the road-crossing structures were underpasses, box-culverts, and pipe-culverts targeting large and mid-sized mammals. There were fewer eco-bridges targeting arboreal mammals and amphibian tunnels targeting herptiles in Japan. In the future, it will be necessary to analyze the factors influencing road-kill and barrier effect of various species and taxa in order to develop mitigation techniques targeting arboreal mammals and herptiles, and to develop quantitative methods for monitoring wild mammals utilizing road-crossing structures as movement corridors.

In a growth chamber, we tested how the seasonal timing of placing a physical barrier (simulating a possible effect of log storage) and inflicting root damage impacted aspen (Populus tremuloides Michx.) root systems and their suckering capability. Roots from 4-year-old saplings were used, and one half of these root systems had the above-ground portion cut in the winter (dormant) while the other half was cut during the growing season in the summer. Damage was inflicted to the roots by driving a large farm tractor over them, and a covering treatment was applied using a polystyrene board to prevent suckers from emerging from the soil. Soil temperatures for the winter-cut root systems were kept at 5 8C over the growing season, using a water bath, while for the summer-cut root systems soil temperatures were maintained at 17 8C over the growing season. In the winter-cut root systems, both log storage and root wounding caused a 40% reduction in living root mass and carbohydrate reserves, as well as reducing sucker numbers and their growth performance. In the summer-cut root systems log storage and root wounding reduced living root mass by approximately 35% as well as sucker growth, but had less of an impact on the number of suckers produced.

The Neovolcanic Belt is a physical and ecologic barrier that has affected plant distribution patterns in central Mexico. It has been proposed that the barrier effect is incomplete due to openings that connect valleys across the Belt and permit floristic interchange. To substantiate the presence of floristic corridors, moss collections were made in the Chalco and Toluca areas and in the valleys of the state of Morelos. About 3594 samples representing 330 species and varieties from 2700 m or below were studied. The tropical species were selected and used as markers to determine possible floristic interchanges. Although the number of species shared between valleys on either side of the Belt indicates that its topographic discontinuities may have permitted it, the time of the interchange of tropical taxa cannot be established. The alpine species may have reached the corridors in the Pleistocene along with species from other elevations.

Roads are widely recognized to represent a barrier to individual movements and, conversely, verges can act as potential corridors for the dispersal of many small mammals. Both barrier and corridor effects should generate a clear spatial pattern in genetic structure. Nevertheless, the effect of roads on the genetic structure of small mammal populations still remains unclear. In this study, we examine the barrier effect that different road types (4-lane highway, 2-lane roads and single-lane unpaved roads) may have on the population genetic structure of three species differing in relevant life history traits: southern water vole Arvicola sapidus, the Mediterranean pine vole Microtus duodecimcostatus and the Algerian mouse Mus spretus. We also examine the corridor effect of highway verges on the Mediterranean pine vole and the Algerian mouse. We analysed the population structure through pairwise estimates of FST among subpopulations bisected by roads, identified genetic clusters through Bayesian assignment approaches, and used simple and partial Mantel tests to evaluate the relative barrier or corridor effect of roads. No strong evidences were found for an effect of roads on population structure of these three species. The barrier effect of roads seems to be site-specific and no corridor effect of verges was found for the pine vole and Algerian mouse populations. The lack of consistent results among species and for each road type lead us to believe that the ability of individual dispersers to use those crossing structures or the habitat quality in the highway verges may have a relatively higher influence on gene flow among populations than the presence of crossing structures per se. Further research should include microhabitat analysis and the estimates of species abundance to understand the mechanisms that underlie the genetic structure observed at some sites

Summary 1. Roads can act as barriers to animal movement, which may reduce population persistence by reducing recolonization of empty habitats and limiting immigration. Appropriate mitigation of this barrier effect (e.g. seasonal road closures, location and design of wildlife over- or underpasses) depends upon whether the animals avoid the road itself or the traffic on the road. Empirical studies of road avoidance to date do not generally differentiate between these. 2. We conducted short- and long-distance translocations and trapping studies of white-footed mice ( Peromyscus leucopus ) and eastern chipmunks ( Tamias striatus ) near two-lane paved roads, which differed widely in traffic amount, from 47 to 15 433 vehicles per day. 3. In the trapping study (13 sites) only five animals moved across a road, in comparison to 36 animals that moved the same distance without an intervening road ( P < 0·0001). In the short-distance translocations (15 sites), 51% of the small mammals that were translocated across roads returned, in comparison to a return rate of 77% of animals that were translocated a similar distance with no intervening road ( P = 0·009). 4. In the long-distance translocation study (24 sites) we found that each intervening road reduced the probability of successful return by about 50%. 5. We found no significant effects of traffic amount on return rates in either the short-distance or the long-distance translocations studies. 6. Small mammal densities were not lower near roads and we found no evidence for a decrease in density near roads with increasing traffic amount. 7. Synthesis and applications. Our results suggest that small mammals avoid the road itself, and not emissions such as noise from the traffic on the roads. Our results imply that the barrier effect of roads on these species cannot be mitigated by measures aimed at reducing traffic amount; other measures such as wildlife passages would be needed.

in reproductive swards, stems appear to act as vertical or horizontal barriers to bite formation, influencing instantaneous intake rate (IIR). The hypothesis was tested that the stems' barrier effect is determined by the physical properties and density of stems. Artificial microswards, consisting of 20-cm leaves and 15-cm stems of Panicum maximum, were offered to three steers (362 kg) in a factorial combination of three stem densities (0, 100 and 400 stems m(-2)) and two levels of stem tensile resistance [low (LTRS) and high tensile-resisting stems (HTRS)]. LTRS were not a barrier to defoliation and did not affect bite depth and bite mass. HTRS acted as both a horizontal barrier and a vertical barrier depressing bite depth (13.4, 13.6 and 5.1 cut for 0, 100 and 400 stems m(-2), respectively), bite area (89.3, 50.8 and 47.6 cm(2) for 0, 100 and 400 stems M-2, respectively), bite mass (0.51, 0.29 and 0.11 g for 0, 100 and 400 stems m(-2), respectively) and IIR (23.8, 10.5 and 3.6 g sec(-2) for 0, 100 and 400 Stems m(-2), respectively). The results confirmed the importance of the density and physical properties of stems as determinants of the stems' barrier effect on bite dimensions and IIR.

Much remains to be learned about how anthropogenic structures affect migration in large mammals. We examined the potential influence of the international railroad in Mongolia on migration in Mongolian gazelles (Procapra gutturosa). We examined gazelle movements and the normalized difference vegetation index (NDVI) on both sides of the railroad. The tracked gazelles never crossed the railroad, despite movements that mainly followed the railroad in winter and higher NDVI values on the opposite side. It is likely that the railroad had a barrier effect on gazelle migration because it split the gazelles' habitat. Our results, although based on an extremely small sample, have utility in indicating approaches that might be useful for examining migration in ungulates. Resumen: Falta mucho por conocer sobre el efecto de estructuras antropogenicas sobre la migracion de mamiferos mayores. Examinamos la potencial influencia del ferrocarril internacional en Mongolia sobre la migracion de gacelas de Mongolia ( Procapra gutturosa). Examinamos los movimientos de las gacelas y el indice de vegetacion de diferencia normalizada (IVDN) a ambos lados de la via ferrea. Las gacelas rastreadas nunca cruzaron la via ferrea, a pesar de que los movimientos mayormente seguian la via en invierno y que los valores de IVDN eran mayores del lado contrario. Es probable que la via ferrea produjera un efecto de barrera sobre la migracion de las gacelas porque dividio al habitat de las gacelas. Nuestros resultados, aunque basados en una muestra extremadamente pequena, son utiles para senalar estrategias que pueden ser utilizadas provechosamente para examinar la migracion de ungulados.

The dose-dependent responses of the slug Deroceras panormitanum and the snail Oxyloma pfeifferi were tested with three novel molluscicides: cinnamamide, copper ammonium carbonate and ureaformaldehyde. Solutions of products were used at concentrations ranging from 0.005% to 1% (active ingredients: 0.05–149 μg/cm2). In a bioassay, antifeedant effects, mortality, repellence and irritation were investigated. Both species were significantly repelled by cinnamamide and a ureaformaldehyde resin at concentrations of 0.5% and 1%, causing a barrier effect. A significant antifeedant effect on D. panormitanum was also seen with those dose-treatment combinations, whereas only Croptex-Fungex® at 0.5% and 0.625% had a significant antifeedant effect on O. pfeifferi. In comparison to the untreated compost, the accumulated leaf damage on treated compost was significantly reduced by all three products at concentrations of 0.5% and above. The behavioural software EthoVision was used for an automated analysis of the behavioural response of D. panormitanum to the irritant effect. All dose-treatment combinations of 0.1% and above significantly reduced the moving activity of the slug, accompanied by severe weight loss and significant increases in mortality with cinnamamide and a ureaformaldehyde resin at 0.5% and 1%. Egg development was completely suppressed at concentrations as low as 0.05%. Significant delays in egg development time were observed with all three molluscicides at concentrations as low as 0.005%. The implications for an integrated control strategy of these pest species are discussed.

The complete mitochondrial genome was determined from a variegated racerunner, Eremias vermiculata, which was collected from north of Tianshan Mountains, Xinjiang, China. The mitogenome sequence was 19,494 bp in size, containing 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and a control region (D-loop), which is similar to the typical mtDNA of vertebrates. All the protein-coding genes in E. vermiculata were distributed on the H-strand, except the ND6 gene and eight tRNA genes, which were encoded on the L-strand. The mitogenome sequence herein will provide fundamental data for further investigating the phylogeographical pattern of E. vermiculata, along with testing the barrier effect of the Tianshan Mountains to gene flow. A preliminary phylogenetic inference has been implemented with five racerunner species and several other related lacertid species.

The human gut is a huge complex ecosystem where microbiota, nutrients, and host cells interact extensively, a process crucial for the gut homeostasis and host development with a real partnership. The various bacterial communities that make up the gut microbiota have many functions including metabolic, barrier effect, and trophic functions. Hence, any dysbiosis could have negative consequences in terms of health and many diseases have been associated to impairment of the gut microbiota. These close relationships between gut microbiota, health, and disease, have led to great interest in using probiotics (i.e. live micro-organisms), or prebiotics (i.e. non-digestible substrates) to positively modulate the gut microbiota to prevent or treat some diseases. This review focuses on probiotics, their mechanisms of action, safety, and major health benefits. Health benefits remain to be proven in some indications, and further studies on the best strain(s), dose, and algorithm of administration to be used are needed. Nevertheless, probiotic administration seems to have a great potential in terms of health that justifies more research.

The effect of the multiline consisting of a rice cultivar, Sasanishiki, and its isogenic lines on the rice blast disease caused by Pyricularia oryzae Cavara was investigated under natural conditions. The blast disease severity and the percent diseased plants in the mixtures were less than that observed in the single line plantings. The blast disease occurrence in the mixture of compatible and incompatible lines was less than that of the compatible lines mixture. Moreover, even in the compatible lines mixture, the rice blast disease severity was depressed significantly. It became apparent that a reduced inoculum density effect and a barrier effect for infection depressed the blast disease, and it was assumed that an induced resistance operated to suppress the blast disease in the Sasanishiki's multiline. Furthermore, the feasibility of using the Sasanishiki multiline of ten isogenic lines with different true resistances was effective for the control of blast diseases.

Infectious prions cause diverse clinical signs and form an extraordinary range of structures, from amorphous aggregates to fibrils. How the conformation of a prion dictates the disease phenotype remains unclear. Mice expressing GPI-anchorless or GPI-anchored prion protein exposed to the same infectious prion develop fibrillar or nonfibrillar aggregates, respectively, and show a striking divergence in the disease pathogenesis. To better understand how a prion's physical properties govern the pathogenesis, infectious anchorless prions were passaged in mice expressing anchorless prion protein and the resulting prions were biochemically characterized. Serial passage of anchorless prions led to a significant decrease in the incubation period to terminal disease and altered the biochemical properties, consistent with a transmission barrier effect. After an intraperitoneal exposure, anchorless prions were only weakly neuroinvasive, as prion plaques rarely occurred in the brain yet were abundant in extracerebral sites such as heart and adipose tissue. Anchorless prions consistently showed very high stability in chaotropes or when heated in SDS, and were highly resistant to enzyme digestion. Consistent with the results in mice, anchorless prions from a human patient were also highly stable in chaotropes. These findings reveal that anchorless prions consist of fibrillar and highly stable conformers. The additional finding from our group and others that both anchorless and anchored prion fibrils are poorly neuroinvasive strengthens the hypothesis that a fibrillar prion structure impedes efficient CNS invasion., Author Summary Prions cause fatal neurodegenerative disease in humans and animals and there is currently no treatment available. The cellular prion protein is normally tethered to the outer leaflet of the plasma membrane by a glycophosphatidyl inositol (GPI) anchor. A rare stop codon mutation in the PRNP gene leads to the production of GPI-anchorless prion protein and the development of familial prion disease, which has been reproduced in mouse models. GPI-anchorless prions in humans or mice form large, dense plaques containing fibrils in the brain that vary from the more common non-fibrillar prion aggregates. Here we investigated the biochemical differences between GPI-anchored and GPI-anchorless prions. We also assessed the capacity of GPI-anchorless prions to spread from entry sites into the central nervous system. We found that infectious GPI-anchorless prions were extraordinarily stable when exposed to protein denaturing conditions. Additionally, we show that GPI-anchorless prions rarely invade the central nervous system and then only after long incubation periods, despite their presence in extraneural tissues including adipose tissue and heart. Our study shows that GPI-anchored prions converted into GPI-anchorless prions become extraordinarily stable, more resistant to enzyme digestion, and are poorly able to invade the nervous system.

Linear landscape elements may act as barriers to the movement of wildlife, inducing genetic sub-structure because barriers impair gene flow. This effect often occurs in response to transportation infrastructure such as freeways, requiring expensive measures, such as overpasses, to re-establish connectivity among separated populations. Here, we present a landscape genetic study using a spatial overlay of landscape elements and genetic clustering based on nuclear microsatellites in roe deer. Our results show that fenced freeways appeared as the main obstacles to gene flow in roe deer within a nationally important wildlife corridor in Switzerland. On the other hand, a wide river only showed a weak barrier effect, whereas a highly frequented but unfenced railway track had no detectable effect on gene flow. Landscape genetic overlays proved helpful in the communication with practical environmental management, as they are intuitively appealing. Furthermore, the chosen approach pointed to the need for setting priorities for building wildlife passages as a connectivity measure in the study landscape and sets the reference line for testing the effectiveness of the measures taken. Lineare Landschaftselemente können als Barrieren für die Bewegungen von Wildtieren wirken. Dadurch kann genetische Struktur entstehen, da Genfluss verhindert wird. Solche Effekte werden oft durch Verkehrsinfrastruktur wie zum beispielsweise Autobahnen verursacht, wodurch teure Massnahmen wie Wildtierbrücken notwendig werden, um die Vernetzung getrennter Populationen wieder herzustellen. Die hier vorgestellte landschaftsgenetische Studie basiert auf einer räumlichen Überlagerungsanalyse von Landschaftselementen und genetischer Gruppierung aufgrund von nukleären Mikrosatelliten bei Rehen. Die Ergebnisse zeigen, dass abgezäunte Autobahnen die hauptsächlichen Hindernisse für den Genfluss bei Rehen innerhalb eines national bedeutenden Wildtierkorridors der Schweiz darstellen. Im Gegensatz dazu hatte ein breiter Fluss nur geringe Barrierewirkung, während eine stark frequentierte, aber nicht abgezäunte Eisenbahnlinie keinen Einfluss auf den Genfluss der Rehe zeigte. Die landschaftsgenetischen Überlagerungsanalysen erwiesen sich als hilfreiches Instrument in der Kommunikation mit Praktikern, da sie intuitiv verständlich sind. Mit diesem Ansatz lassen sich auch Prioritäten setzen bei der Realisierung von Wildtierpassagen als Vernetzungsmassnahme in der untersuchten Landschaft. Die hier vorgestellten Resultate können zudem als Referenz für eine nachfolgende Wirkungskontrolle dienen.

An experimental model developed in our laboratory was used for this study, i.e. a minimum microbiota showing resistance to Clostridium difficile colonisation isolated from the gut of the hamster. Only trixenic mice (C indolis, C. cocleatum, Eubacterium sp.) were able to eliminate the target strain C. difficile. With the ‘Swiss rolls’ technique and scanning electron microscopy, it was shown that at each step of colonisation the caecal barrier microbiota was observed in the mucus present on the surface of the caecal mucous membrane and at the openings of the intestinal crypts, but never in the mucus situated inside the crypts. Moreover, some differences in mucus colonisation could be seen related to each colonisation step. In C. difficile monoxenic mice, these bacteria colonised the mucus in the same fashion as did the bacteria responsible for colonisation resistance. The mechanisms of this barrier effect against C. difficile remain unknown, although it may involve competition between C. difficile and the b...

1. Barrier effect. Relevant models should include an anaerobic dominant flora that antagonizes minor bacterial populations such as drug resistant E. coli. 2. Anaerobes vs. aerobes. Aerobe counts are more precise and much less time consuming than anaerobe counts. Minor populations of drug resistant aerobes are sensitive markers of the ecosystem balance, and are directly relevant to the potential risk of antimicrobial residues. 3. MIC vs. plate counts. The determination of minimum inhibitory concentrations ( MIC ) of selected clones is time consuming, does not detect subdominant resistance (less than 1 %), and the MIC shift is difficult to test statistically. In contrast, direct counts of bacteria on drug supplemented media allows a rapid measure of minor resistant populations. 4. Statistics: Most published designs do not include adequate statistical evaluation. This is critical for trials made in conventional humans and animals, where data are highly variable. 5. Human trials: The lowest concentration of antibiotic tested in human volunteers (2mg oxytetracycline /d for 7d in 6 subjects) significantly increased the proportion of resistant fecal enterobacteria (P=0.05). However, the huge day-to-day and inter-individual variations of human floras make this evidence rather weak. 6. Gnotobiotic mice inoculated with human flora are living isolated models in which the effect of any antimicrobial on the human gut flora can be tested. This in vivo model does include the barrier effect of dominant anaerobes. Inter-individual and day-to-day variations of bacterial populations are lower in those mice than in humans. 7. Most resistant enterobacteria in the human gut of untreated people come from bacterial contamination of raw foods. The relative contribution of residues in selecting antibiotic resistance seems to be low when compared to bacterial contamination.

Laboratory experiments were carried out to study water kinematics induced by air bubble barriers, to evaluate their effectiveness in protecting water intakes from jellyfish attack. The experiments ...

The pathogenesis of venous ulceration is thought to involve the formation of fibrin cuffs around dermal capillaries. Consistent with a barrier effect of fibrin, it has been shown that the dermal diffusion of oxygen, as measured by transcutaneous oxygen pressure (TcPO2), is decreased in limbs affected by venous ulcer. However, it is unknown whether oxygen diffusion around the perimeter of venous ulcers is uniformly affected. In this study, we investigated TcPO2 values at four different quadrants around the ulcers of 14 patients, the contralateral leg of five patients with unilateral ulcers, and the leg of six normal individuals. These values were also compared to TcPO2 measurements at the chest. Our results indicate that, whereas TcPO2 values in limbs affected by venous ulcers are much lower than normal, there is a great deal of variability in oxygen diffusion around individual ulcers. These findings may represent a heterogeneity in the disease process affecting the leg.

Mouen Bedimo, J. A., Njiayouom, I., Bieysse, D., Ndoumbe Nkeng, M., Cilas, C., and Notteghem, J. L. 2008. Effect of shade on Arabica coffee berry disease development: Toward an agroforestry system to reduce disease impact. Phytopathology 98:1320-1325. Coffee berry disease (CBD), caused by Colletotrichum kahawae, is a major constraint for Arabica coffee cultivation in Africa. The disease is specific to green berries and can lead to 60% harvest losses. In Cameroon, mixed cropping systems of coffee with other crops, such as fruit trees, are very widespread agricultural practices. Fruit trees are commonly planted at random on coffee farms, providing a heterogeneous shading pattern for coffee trees growing underneath. Based on a recent study of CBD, it is known that those plants can reduce disease incidence. To assess the specific effect of shade, in situ and in vitro disease development was compared between coffee trees shaded artificially by a net and trees located in full sunlight. In the field, assessments confirmed a reduction in CBD on trees grown under shade compared with those grown in full sunlight. Artificial inoculations in the laboratory showed that shade did not have any effect on the intrinsic susceptibility of coffee berries to CBD. Coffee shading mainly acts on environmental parameters in limiting disease incidence. In addition to reducing yield losses, agroforestry system may also be helpful in reducing chemical control of the disease and in diversifying coffee growers’ incomes.

The human intestinal microbiota plays a pivotal role in human nutrition and health by promoting the supply of nutrients, preventing pathogen colonization and shaping and maintaining normal mucosal immunity. The depletion of the individual microbiota can result in a higher susceptibility to enteropathogenic bacteria infection. In order to reduce this risk, the use of food supplements containing probiotic bacteria has been recently addressed. In this paper, we investigate the protective role toward enteropathogen infection of probiotic strains belonging to Lactobacillus and Bifidobacterium. According to our experimental data, Lactobacillus acidophilus Bar13, L. plantarum Bar10, Bifidobacterium longum Bar33 and B. lactis Bar30 were effective in displacing the enteropathogens Salmonella typhimurium and Escherichia coli H10407 from a Caco-2 cell layer. Moreover, L. acidophilus Bar13 and B. longum Bar33 have been assessed for their immunomodulatory activity on IL-8 production by HT29 cells. Both strains showed the potential to protect enterocytes from an acute inflammatory response. These probiotic strains are potential candidates for the development of new functional foods helpful in counteracting enteropathogen infections.

Within the framework of appraising the new type of forest damage, the epidermis of two-year-old spruce (Picea abies) needles was investigated as a possible site for primary attack by air pollutants using light and scanning electron microscopy. Depending upon the extent of the macroscopically visible needle leaf disease, a degeneration process of the cuticular, stomatal and epidermal structures leading to the lethal destruction of the needle surface was observed. Stomatal and epidermal cells become increasingly deformed or collapsed showing increasing discolouration due to phenolic deposits. Additionally, the erosion of stomatal waxes is accelerated, leading initially to a temporary occlusion of the stomata, and then to a wide opening of the antechamber following a complete decomposition of the plug. Surface lesions indicating early damage to the epidermal tissue already occur on slightly yellowed needles. The barrier effect of the spruce needle epidermis on exogenous stressors could thereby already be reduced at an early stage, triggering incipient losses of structural resistance. ZusammenfassungVerlust der strukturellen Resistenz in Nadeln geschiadigter Fichten immissionsbelasteter Standorte II. Epidermis und Stomata (Abschlusgewebe) In Zusammenhang mit dem Auftreten neuartiger Waldschaden wurde das Absehlusgewebe zweijahriger Fichtennadeln als vermutlieher primarer Angriffsort fur Luftschadstoffe lichi-undelektronenmikroskopisch uncersucht. In Abhangigkeit von dem Ausmas der makroskopisch sichtbaren Schiaden des Nadelblattes konnte eine Reihung der Degeneration der kutikularen, stomatiaren und epidermalen Strukturen bis hin zu einer vollstandigen Zerstarung der Nadeloberflache vorgenommen werden. Die stomataren und epidermalen Zellen erweisen sich fortschreitend deformiert oder kollabiert und zeigen zunehmende Verfarbungen bedingt durch phenolische Ablagerungen. Weiter findet eine beschleungte Erosion der stomataren Wachse statt, die zuniachst zu einem zeitweiligen Versfhlus der Stomata und schlieslich nach einer volligen Zerstorung des Wachspfropfens zu einer weitgehenden Freilegung des Vorhofes fahrt. Oberflachenlasionen, die friabe Schadigungen des epidermalen Gewebes anzeigen, treten bereits bei geringfiagig vergiibten Nadeln auf. Die absehirmende Wirkung des Abschlusgewebes des Nadelblattes gegeniuber exogenen Stresaoren kann damit bereits auf einer friahen Stufe reduziert werden und dies konnte den Beginn des Verlustes der strukturellen Resistenz auslasen.

BACKGROUND: Treating soil with insecticides is thought to be an effective method for termite control. Speed of action and repellency of insecticides are important factors for discussing their barrier effects as soil-treatment termiticides. The chemical barrier effect of microencapsulated fenobucarb against Coptotermes formosanus Shiraki was examined in the laboratory. RESULTS: Fenobucarb had a significantly faster lethal effect when applied to the mouthparts than to the tergites of worker termites. Soil that had been treated with ≥ 50 mg kg−1 of microencapsulated fenobucarb had a barrier effect within a single day, and could stop or retard the penetration of termites for 7 days. Microencapsulated fenobucarb did not act as a repellent, as indicated by a gradual increase in mortality at ≥ 50 mg kg−1 with slight penetration into the treated soil during the 7 day test. CONCLUSION: The results suggest that microencapsulated fenobucarb is a fast-acting termiticide, with a good barrier effect as a soil treatment, that also acts as a reduced repellent, retarding entry of termites into treated soil. Copyright © 2007 Society of Chemical Industry

Increasingly wildlife managers and land managers are challenged to maintain the viability and connectivity among large mammal populations. Thus, it is important that effective highway crossings are identified and optimized with respect to construction cost, facilitation of ungulate movements, and ability to reduce wildlife-vehicle collisions. The use of exclusion fencing to reduce ungulate-vehicle collisions is commonly installed along Swedish highways. However, exclusion fences may pose a threat to the viability of wildlife populations because they serve as barriers to individual movements and may limit accessibility to resources. Various types of wildlife crossings intended to reduce road-kills and increase habitat connectivity across fenced highways have been constructed throughout the world. Previous studies have evaluated the importance of structure design and size for many ungulate species, but few studies involved moose (Alces alces) which is the target species for most large ungulate mitigations in Sweden. The results of the studies are intended to facilitate the development of wildlife crossings and conventional road passages to meet ungulate demands. We monitored moose fitted with GPS radio collars and characterized their space and habitat use patterns in southwestern Sweden. Moose had seasonal differences in habitat selection within their home range, and generally preferred clear-cuts and early successional forest, boreal forest, and glades, but avoided agricultural areas and open water. We used infrared remote cameras, track surveys, and GPS telemetry to monitor the use of wildlife crossings and conventional road passages by moose and roe deer (Capreolus capreolus). The upgrading of a non-fenced road to a fenced highway with three wildlife crossings decreased the moose movements across the highway by 67-89 %. Overpass use by moose and roe deer declined with increased traffic volume on the highway and both species walked during periods of low highway traffic volumes and shifted to trotting as traffic intensity increased. Low rates of human disturbances and proximity to forest edges increased use of highway underpasses by roe deer. Moose used large underpasses to a higher degree than small.

Six isogenic lines with complete resistance genes (R-genes) on the genetic background of the japonica rice variety Koshihikari were developed. BL1 has Piz-t, BL2 has Pii and Pita-2, BL3 has Pib, BL4 has Pik-p, BL5 has Pik-m, and BL6 has Piz and Pia, respectively. We adopted these lines for mixed planting, because we expected them to have a barrier effect. Based on the distribution of the blast race, we determined that we should mix BL 1, BL2 and BL4 in a ratio of 4, 4 and 2. After mixing, we investigated the barrier effect under moderate and heavy epidemics of disease. The barrier effect was confirmed under the moderate conditions even when the mix contained 40% of the susceptible variety, but the ratio of the susceptible variety could only be 20% under the heavy conditions. This suggests that the mixing ratio of the susceptible varieties should be restricted to within 20% under a heavy blast epidemic. Furthermore, BL showed strong resistance to the panicle blast that occurred during the ripening period. In this case, the BL yield was 1.7 times as high as that of Koshihikari.

Mucosal epithelial surfaces such as the respiratory system, the gastrointestinal and urogenital tracts are sites where allochthonous microorganisms can encounter, and in some instances, infect the host. Some mucosal surfaces, such as the heavily colonised distal intestine, are physiologically colonised by a commensal microflora that entertains symbiotic interactions with its host. Others, such as the distal respiratory airways, remain relatively sterile. The commensal intestinal microflora can be considered an organ with a hugh diversity of (bacterial) cells that, in turn, perform different important functions for the body (Brassart and Schiffrin, 1997).

The history of the establishment of safe residue levels is reviewed. Current internation agreements within the FAO/WHO Codex Alimentarius programme and EC legislation establish these levels on the basis of toxicology studies. In addition to conventional toxicological effects, other effects such as the effects of drugs on the immune system, and pharmacological effects should be taken into account. The latter also include specific effects of residues of veterinary antibiotics on the human gut flora. The methods for the assessment of these effects are evaluated. Studies in human volunteers enable the establishment of a no-effect level in conditions which are the most closely mimicking the conditions of use. However, they are less favourable from a practical and ethical point of view. Studies with animal models can be used; for example human intestinal flora can be inoculated to gnotobiotic mice. These models need nevertheless to be further validated. Studies in vitro, such as those to determine the MIC, are relatively simple to carry out and inexpensive, but are not always representative of the relevant bacteria, and may not take into account factors such as, Ph, anaerobiosis and the barrier effect.

Pseudomonas aeruginosais a formidable opportunistic pathogen. Pseudomonal infections are very common among hospitalized patients, particularly in the ICU. They are notoriously difficult to treat and account for substantial morbidity and mortality. One of the major factors contributing to the high death rate associated with these infections is the broad resistance to common antimicrobial agents which typifies this organism. One of the least well understood aspects of this resistance is the barrier effect of the outer membrane. In this chapter, I will briefly survey newer information pertaining to the role of cell wall barriers as mechanisms of antibiotic resistance in P. aeruginosa.

A model is proposed of mechanisms which might affect the progress of Erysiphe graminis f. sp. hordei in mixtures of barley varieties. Results obtained from two field trials indicate that the efffect of mixtures may be panitioned into three categoriesof the influence of the reduced density of the susceptible plants, the barrier effect of the resistant plants, and the induced resistance due to the non-virulent pathogen biotypes. In the early stages of plant growth the lower density of susceptible plants accounted for most of the reduction in pathogen development in mixtures. As the epidemic progressed, the barrier and induced resistance effects increased in importance and the total mixture effect was at a maximum mid-way through epidemic development. Towards the end of the trials the overall mixture effect declined though the influence of induced resistance was at its maximum. The reasons for these changes and their implications for the use of host varietal mixtures in disease control are discussed. Mixtures also protected the crop against a pathogen other than the target organism.

This paper presents the main contributions of a group of French scientists, involved in the field of gnotoxeny, to the present knowledge of the interactions between the host animal and its microflora It is possible to analyse these relationships by means of two recently developed techniques: (a) use of ‘axenic’ (germ-free) animals and of ‘gnotoxenic’ animals inoculated with known bacterial populations; and (b) perfecting of bacteriological techniques for the quantitative differential analysis of the various gastro-intestinal bacterial populations, in particular the strictly anaerobic species. Various examples of the action of the gastro-intestinal microflora on the nutritional physiology of the host are given, including action on growth, on carbohydrate, nitrogen, lipid, mineral and vitamin metabolism, and on the anatomy of the digestive tract. Finally, various examples are included showing how the composition of the diet may effect the equilibrium of the gastro-intestinal microflora, and especially how it may modify the barrier effect of the bacteria established in the digestive tract towards the environmental bacteria penetrating the ecosystem.

It is commonplace for islands to have fewer bird species than adjoining mainlands. In this respect Tasmania is no different to other islands. Lack (1969) has pointed out that until recently this was attributed to difficulties of dispersal, a view which he rejected. The two most recent studies of the Tasmanian avifauna (Ridpath & Moreau, 1966; Kikkawa & Pearse, 1969) both attributed the low number of species breeding in Tasmania to the barrier effect of Bass Strait. In this chapter it is argued that the barrier effect alone is inadequate and that additional factors must be taken into account if the impoverishment of the Tasmanian avifauna is to be explained adequately. The comprehensive theory of island biogeography proposed by Macarthur & Wilson (1963, 1967) is believed to provide this explanation.

Roads and traffic are pervasive components of landscapes throughout the world: they cause wildlife mortality, disrupt animal movements, and increase the risk of extinction. Expensive engineering solutions, such as overpasses and tunnels, are increasingly being adopted to mitigate these effects. Although some species readily use such structures, their success in preventing population extinction remains unknown. Here, the authors use population viability modeling to assess the effectiveness of tunnels for the endangered Mountain Pygmy-possum (Burramys parvus) in Australia. The underpasses reduced, but did not completely remove, the negative effects of a road. The expected minimum population size of a “reconnected” population remained 15% lower than that of a comparable “undivided” population. The authors propose that the extent to which the risk of extinction decreases should be adopted as a measure of effectiveness of mitigation measures and that the use of population modeling become routine in these evaluations.

Rapids, falls, and cascades might act as barriers for freshwater species, determining the species community up- and downstream of barriers. However, they affect community composition not only by acting as barriers but also by their influence on environmental gradients. Moreover, the directional dispersal of species along the watercourse might determine community composition. A suitable system to study these differential effects is the Congo River, the world’s second largest river by discharge. The small ‘Upper Congo Rapids’ ecoregion features several rapids known as barrier for fishes. The Wagenia Cataracts at the town of Kisangani constitute the strongest drop of the Congo River and several studies have emphasized its role as barrier for fish distribution. Alternative explanations for this pattern, however, are rarely evaluated. Though mollusks represent a vital component of the macrozoobenthos, with distribution patterns and underlying drivers often distinct from that of fishes, virtually no field surveys of the Congo River have been reported for decades. We collected and determined mollusks of 51 stations, recorded environmental conditions, and generated proxies for directional species dispersal and an indirect barrier effect. Those variables were subjected to distance-based redundancy analyses and variation partitioning in order to test whether the mollusk community compositions are better explained by an individual or combined influence of the direct and indirect effect of the cataract barrier, environmental conditions, and downstream-directed dispersal. Our survey showed an exclusive upstream/downstream distribution for just four out of the 19 species, suggesting a limited barrier effect. We revealed no direct influence of the barrier itself on community composition but of substrate type. However, we found an indirect effect of the barrier through replacing spatially structured communities upstream of the cataract with more uniform ones downstream. Downstream‑directed dispersal explained the highest fraction of variation in mollusk communities. Thus, environmental factors, the indirect cataract effect, and downstream-directed spatial proxies model mollusk community composition in concert. These results support previous studies showing a multi-factorial imprint on communities. However, a large fraction of variation community composition remained unexplained, potentially due to flood plain dynamics that (re-)shape mollusk communities constantly and a high temporal turnover, evidenced by the comparison with historical surveys. This is likely caused by the growth of Kisangani and resulting human activities. A monitoring system could allow better assessments of these impacts on communities and the conservation status of endemic species in the Wagenia Cataracts.

Microbial communities are continuously exposed to the arrival of alien species. In complex environments such as soil, the success of invasion depends on the characteristics of the habitat, especially the diversity and structure of the residing bacterial communities. While most data available on microbial invasion relies on experiments run under constant conditions, the fate of invading species when the habitat faces disturbances has not yet been addressed. Here, we designed experiments to assess the consequences of habitat disturbance on the success of ongoing microbial invasion. We investigated (i) if disturbance-induced alterations in resident microbial communities could mitigate or facilitate invasion of Listeria monocytogenes, (ii) if disturbance itself could either improve or reduce the invader's fitness and (iii) if the invading species alters the structure of indigenous microbial communities. Our data show that environmental disturbances affect invasion patterns of L. monocytogenes in soils. Intriguingly, successful invasion was recorded in a regimen of disturbances that triggered small changes in microbial community structure while maintaining high bacterial diversity. On the opposite, dramatic decline of the invader was recorded when disturbance resulted in emergence of specific communities albeit concomitant with a diversity loss. This suggests that community composition is more important than its diversity when it comes to prevent the establishment of an invading species. Finally, shifts in bacterial communities during the disturbance event were strengthened by the presence of the invader indicating a major impact of invasion on microbial diversity when the habitat faces disturbance.