Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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    ‘Force of Nature’ : climate shocks, food crises and conflict in Colonial Africa and Asia, 1880-1960
    Papaioannou, Kostadis J. - \ 2017
    Wageningen University. Promotor(en): E.H.P. Frankema; E.H. Bulte. - Wageningen : Wageningen University - ISBN 9789463431668 - 238
    climatic change - environmental degradation - environmental impact - agricultural development - agriculture - agriculture and environment - historical ecology - history - colonialism - colonization - africa - asia - nigeria - rainfed agriculture - rain - klimaatverandering - milieuafbraak - milieueffect - landbouwontwikkeling - landbouw - landbouw en milieu - historische ecologie - geschiedenis - kolonialisme - kolonisatie - afrika - azië - nigeria - regenafhankelijke landbouw - regen

    “Global climate change poses one of the most urgent challenges of our age. The increasing frequency and intensity of weather shocks, such as heat waves, droughts, floods, and hurricanes, are all anticipated to adversely affect conditions of agricultural production, and jeopardize efforts to achieve global food security. In recent years, there has been a rapidly growing body of literature across multiple disciplines aiming to quantify and assess the adverse consequences of climate on relatively poor rural societies. Building entirely on original primary sources, this dissertation provides evidence that weather shocks raised property crime, triggered civil conflict and shaped patterns of human settlement in British colonial Africa and Asia during the first half of the twentieth century (~1880-1960). By merging the theoretical and empirical insights of several strands of literature (e.g. economics, history, geography), this dissertation has both academic and social merit. Its academic merit lies in its promise to disentangle the net effect of climate on societies from the many other contextual factors that may affect them. And its social merit lies in its capacity to reveal key factors that can mitigate the adverse consequences of weather shocks, enabling tailor-made policy interventions. In sum, the present dissertation contributes to a better understanding of long-term agrarian development in tropical Africa and Asia, offering fresh input to academic debates on how to mitigate the effects of weather extremes”

    Non-Typhoidal Salmonella Colonization in Chickens and Humans in the Mekong Delta of Vietnam
    Trung, N.V. ; Carrique-Mas, J.J. ; Nghia, N.H. ; Tu, L.T.P. ; Mai, H.H. ; Tuyen, H.T. ; Campbell, J. ; Nhung, N.T. ; Nhung, H.N. ; Minh, P.V. ; Chieu, T.T.B. ; Hieu, T.Q. ; Mai, N.T.N. ; Baker, S. ; Wagenaar, J.A. ; Hoa, N.T. ; Schultsz, C. - \ 2017
    Zoonoses and Public Health 64 (2017)2. - ISSN 1863-1959 - p. 94 - 99.
    antimicrobial resistance - chickens - colonization - humans - Non-typhoidal Salmonella - Vietnam
    Salmonellosis is a public health concern in both the developed and developing countries. Although the majority of human non-typhoidal Salmonella enterica (NTS) cases are the result of foodborne infections or person-to-person transmission, NTS infections may also be acquired by environmental and occupational exposure to animals. While a considerable number of studies have investigated the presence of NTS in farm animals and meat/carcasses, very few studies have investigated the risk of NTS colonization in humans as a result of direct animal exposure. We investigated asymptomatic NTS colonization in 204 backyard chicken farms, 204 farmers and 306 matched individuals not exposed to chicken farming, in southern Vietnam. Pooled chicken faeces, collected using boot or handheld swabs on backyard chicken farms, and rectal swabs from human participants were tested. NTS colonization prevalence was 45.6%, 4.4% and 2.6% for chicken farms, farmers and unexposed individuals, respectively. Our study observed a higher prevalence of NTS colonization among chicken farmers (4.4%) compared with age-, sex- and location- matched rural and urban individuals not exposed to chickens (2.9% and 2.0%). A total of 164 chicken NTS strains and 17 human NTS strains were isolated, and 28 serovars were identified. Salmonella Weltevreden was the predominant serovar in both chickens and humans. NTS isolates showed resistance (20–40%) against tetracycline, chloramphenicol, sulfamethoxazole-trimethoprim and ampicillin. Our study reflects the epidemiology of NTS colonization in chickens and humans in the Mekong delta of Vietnam and emphasizes the need of larger, preferably longitudinal studies to study the transmission dynamics of NTS between and within animal and human host populations.
    Invasive behavior of Campylobacter jejuni in immunosuppressed chicken
    Vaezirad, Mahdi M. ; Keestra-Gounder, A.M. ; Zoete, Marcel R. de; Koene, Miriam G. ; Wagenaar, Jaap A. ; Putten, Jos P.M. van - \ 2017
    Virulence 8 (2017)3. - ISSN 2150-5594 - p. 248 - 260.
    Campylobacter - chicken - colonization - glucocorticoids - innate immunity - invasion - Toll-like receptor
    Campylobacter jejuni is a predominant cause of gastroenteritis in humans but rather harmless in chickens. The basis of this difference is unknown. We investigated the effect of the chicken immune defense on the behavior of C. jejuni using glucocorticoid (GC)-treated and mock-treated 17-day old Ross 308 chicken bearing in mind that GCs have immunosuppressive effects and dampen the innate immune response. The effect of GC administration on the behavior of C. jejuni was compared with that on infection with Salmonella Enteritidis to address possible microbe-associated differences. Our results revealed that GC treatment fastened the intestinal colonization of C. jejuni (p <0.001) and enhanced its dissemination to the liver (p = 0.007). The effect of GC on intestinal colonization of S. Enteritidis was less pronounced (p = 0.033) but GC did speed up the spread of this pathogen to the liver (p <0.001). Cytokine transcript analysis showed an up to 30-fold reduction in baseline levels of IL-8 mRNA in the cecal (but not spleen) tissue at Day 1 after GC treatment (p <0.005). Challenge with C. jejuni strongly increased intestinal IL-8, IL-6, and iNOS transcript levels in the non-GC treated animals but not in the GC-treated birds (P <0.005). In vitro assays with chicken macrophages showed that GC dampened the TLR agonist- and C. jejuni induced-inflammatory gene transcription and production of nitric oxide (P <0.005). Together, the results support the hypothesis that C. jejuni has the intrinsic ability to invade chicken tissue and that an effective innate immune response may limit its invasive behavior.
    Early plant recruitment stages set the template for the development of vegetation patterns along a hydrological gradient
    Fraaije, R.G.A. ; Braak, C.J.F. ter; Verduyn, B. ; Breeman, L.B.S. ; Verhoeven, J.T.A. ; Soons, M.B. - \ 2015
    Wageningen UR
    biodiversity - colonization - environmental filtering - lowland streams - niche segregation - plant community assembly - riparian zones - wetland restoration
    1. Recruitment processes are critical components of a plant's life cycle. However, in comparison with later stages in the plant life cycle (e.g. competition among adults), relatively little is known about their contribution to the regulation of plant species distribution. Particularly little is known about the individual contributions of the three main recruitment processes—germination, seedling survival, and seedling growth—to community assembly, while quantitative information on these contributions is essential for a more mechanistic understanding of the regulation of plant species distribution and biodiversity. 2. Riparian zones along streams provide a globally-relevant case study for evaluating the importance of the different stages of plant recruitment. The natural hydrological gradients of stream riparian zones are currently being restored after a period of worldwide habitat degradation. To identify how recruitment contributes to vegetation patterns and biodiversity in riparian zones, we carried out field experiments at restored lowland streams. We quantified the germination of introduced seeds, and survival and growth of introduced seedlings of 17 riparian plant species across a gradient from the stream channel to upland. 3. The hydrological gradient of riparian zones acted as a strong environmental filter on all three recruitment processes, through imposing an abiotic limitation (excess water) at low elevations and a resource limitation (water shortage) at higher elevations. Other variables, such as soil organic matter content and nutrient availability, only affected recruitment marginally. 4. Species-specific patterns of environmental filtering initiated niche segregation along the riparian gradient during all three recruitment processes, but particularly during germination and seedling growth. These recruitment niches appeared strongly related to indicator values for adult distribution optima, suggesting that at least some riparian plant species may have evolutionary adaptations that promote recruitment under favourable hydrological conditions for adult growth and reproduction. 5. Our results suggest that strong environmental filtering during germination and seedling growth plays an important role in determining later adult distributions, by forming the spatial template on which all subsequent processes operate. In addition to well-known mechanisms, such as competitive exclusion at the adult stage, environmental filtering during early recruitment stages already strongly affect plant distribution and diversity.
    Early-season movement dynamics of phytophagous pest and natural enemies across a native vegetation-crop ecotone
    Macfadyen, S. ; Hopkinson, J. ; Parry, H. ; Neave, M.J. ; Bianchi, F.J.J.A. ; Zalucki, M.P. ; Schellhorn, N.A. - \ 2015
    Agriculture, Ecosystems and Environment 200 (2015). - ISSN 0167-8809 - p. 110 - 118.
    managing ecosystem services - agricultural landscape - biological-control - spatial scales - dispersal - colonization - predators - ecology - parasitoids - suppression
    There is limited understanding about how insect movement patterns are influenced by landscape features, and how landscapes can be managed to suppress pest phytophage populations in crops. Theory suggests that the relative timing of pest and natural enemy arrival in crops may influence pest suppression. However, there is a lack of data to substantiate this claim. We investigate the movement patterns of insects from native vegetation (NV) and discuss the implications of these patterns for pest control services. Using bi-directional interception traps we quantified the number of insects crossing an NV/crop ecotone relative to a control crop/crop interface in two agricultural regions early in the growing season. We used these data to infer patterns of movement and net flux. At the community-level, insect movement patterns were influenced by ecotone in two out of three years by region combinations. At the functional-group level, pests and parasitoids showed similar movement patterns from NV very soon after crop emergence. However, movement across the control interface increased towards the end of the early-season sampling period. Predators consistently moved more often from NV into crops than vice versa, even after crop emergence. Not all species showed a significant response to ecotone, however when a response was detected, these species showed similar patterns between the two regions. Our results highlight the importance of NV for the recruitment of natural enemies for early season crop immigration that may be potentially important for pest suppression. However, NV was also associated with crop immigration by some pest species. Hence, NV offers both opportunities and risks for pest management. The development of targeted NV management may reduce the risk of crop immigration by pests, but not of natural enemies.
    Early feeding and early life housing conditions influence the response towards a noninfectious lung challenge in broilers
    Simon, K. ; Vries Reilingh, G. de; Bolhuis, J.E. ; Kemp, B. ; Lammers, A. - \ 2015
    Poultry Science 94 (2015)9. - ISSN 0032-5791 - p. 2041 - 2048.
    intestinal immune-responses - symbiotic bacteria - delayed access - laying hens - germ-free - system - colonization - performance - maturation - microbiota
    Early life conditions such as feed and water availability immediately post hatch (p.h.) and housing conditions may influence immune development and therefore immune reactivity later in life. The current study addressed the consequences of a combination of these 2 early life conditions for immune reactivity, i.e., the specific antibody response towards a non-infectious lung challenge. Broiler chicks received feed and water either immediately p.h. or with a 72 h delay and were either reared in a floor or a cage system. At 4 weeks of age, chicks received either an intra-tracheally administered Escherichia coli lipopolysaccharide (LPS)/Human Serum Albumin (HuSA) challenge or a placebo, and antibody titers were measured up to day 14 after administration of the challenge. Chicks housed on the floor and which had a delayed access to feed p.h. showed the highest antibody titers against HuSA. These chicks also showed the strongest sickness response and poorest performance in response to the challenge, indicating that chicks with delayed access to feed might be more sensitive to an environment with higher antigenic pressure. In conclusion, results from the present study show that early life feeding strategy and housing conditions influence a chick's response to an immune challenge later in life. These 2 early life factors should therefore be taken into account when striving for a balance between disease resistance and performance in poultry.
    Bright fluorescent Streptococcus pneumoniae for live cell imaging of host-pathogen interactions
    Kjos, M. ; Aprianto, R. ; Fernandes, V.E. ; Andrew, P.W. ; Strijp, J.A.G. van; Nijland, R. ; Veening, J.W. - \ 2015
    Journal of Bacteriology 197 (2015)5. - ISSN 0021-9193 - p. 807 - 818.
    epithelial-cells - gene-expression - pneumococcal virulence - bacillus-subtilis - in-vivo - protein - capsule - colonization - disease - invasion
    Streptococcus pneumoniae is a common nasopharyngeal resident in healthy people, but at the same time one of the major causes of infectious diseases such as pneumonia, meningitis and sepsis. The shift from commensal to pathogen and its interaction with host cells is poorly understood. One of the major limitations for research on pneumococcal-host interactions is the lack of suitable tools for live cell imaging. To address this issue, we developed a generally applicable strategy to create genetically stable, highly fluorescent bacteria. Our strategy relies on fusing superfolder green fluorescent protein (GFP) or a far-red fluorescent protein (RFP) to the abundant histone-like protein HlpA. Due to efficient translation and limited cellular diffusion of these fusions, the cells are 25-fold brighter than the currently best available imaging S. pneumoniae strain. These novel bright pneumococcal strains are fully virulent and the GFP-reporter can be used for in situ imaging in mouse tissue. We used our reporter strains to study the effect of the polysaccharide capsule, a major pneumococcal virulence factor, on different stages of infection. By dual-color live cell imaging experiments, we show that unencapsulated pneumococci adhere significantly better to human lung epithelial cells compared to encapsulated strains, in line with previous data obtained by classical approaches. We also confirm with live cell imaging that the capsule protects pneumococci from neutrophil phagocytosis, demonstrating the versatility and usability of our reporters. The described imaging tools will pave the way for live cell imaging of pneumococcal infection and help understand the mechanisms of pneumococcal pathogenesis.
    Simulating distal gut mucosal and luminal communities using packed-column biofilm reactors and an in vitro chemostat model
    McDonald, J.A. ; Fuentes, S. ; Schroeter, K. ; Heikamp-de Jong, G.A.M. ; Khursigara, C.M. ; Vos, W.M. de; Allen-Vercoe, E. - \ 2015
    Journal of Microbiological Methods 108 (2015). - ISSN 0167-7012 - p. 36 - 44.
    human intestinal microbiota - motile bacteria - clindamycin - mucin - diversity - colonization - resistance - stability - system - akkermansia
    In vivo studies of human mucosal gut microbiota are often limited to end-point analyses and confounded by bowel cleansing procedures. Therefore, we used biofilm reactors to incorporate a simulated mucosal environment into an in vitro gut chemostat model. Communities developed were complex, reproducible, distinct, and representative of in vivo communities.
    Transmission of Actinobacillus pleuropneumoniae among weaned piglets on endemically infected farms
    Tobias, T.J. ; Bouma, A. ; Broek, J. van den; Nes, A. van; Daemen, A.J.J.M. ; Wagenaar, J.A. ; Stegeman, J.A. ; Klinkenberg, D. - \ 2014
    Preventive Veterinary Medicine 117 (2014)1. - ISSN 0167-5877 - p. 207 - 214.
    between-pen transmission - acquired colostral antibodies - within-pen - airborne transmission - pigs - serotype-2 - virus - herd - quantification - colonization
    Clinical outbreaks due to Actinobacillus pleuropneumoniae occur recurrently, despite the wide-scale use of antimicrobials or vaccination. Therefore, new approaches for the prevention and control of these outbreaks are necessary. For the development of alternative measures, more insight into the transmission of the bacterium on farms is necessary. The aim of this cohort study was to quantify transmission of A. pleuropneumoniae amongst weaned piglets on farms. We investigated three possible transmission routes: (i) indirect transmission by infected piglets within the same compartment, (ii) transmission by infected pigs in adjacent pens and (iii) transmission by direct contact within pens. Additionally, we evaluated the effect of independent litter characteristics on the probability of infection. Two farms participated in our study. Serum and tonsil brush samples were collected from sows pre-farrowing. Serum was analysed for antibodies against Apx toxins and Omp. Subsequently, tonsil brush samples were collected from all piglets from these dams (N = 542) in three cohorts, 3 days before weaning and 6 weeks later. Tonsil samples were analysed by qPCR for the presence of the apxIVA gene of A. pleuropneumoniae. Before weaning, 25% of the piglets tested positive; 6 weeks later 47% tested positive. Regression and stochastic transmission models were used to assess the contribution of each of the three transmission routes and to estimate transmission rates. Transmission between piglets in adjacent pens did not differ significantly from that between non-adjacent pens. The transmission rate across pens was estimated to be 0.0058 day(-1) (95% CI: 0.0030-0.010), whereas the transmission rate within pens was ten times higher 0.059 day(-1) (95% CI: 0.048-0.072). Subsequently, the effects of parity and serological response of the dam and litter age at weaning on the probability of infection of pigs were evaluated by including these into the regression model. A higher dam ApxII antibody level was associated with a lower probability of infection of the pig after weaning; age at weaning was associated with a higher probability of infection of the pig after weaning. Finally, transmission rate estimates were used in a scenario study in which the litters within a compartment were mixed across pens at weaning instead of raising litter mates together in a pen. The results showed that the proportion of infected piglets increased to 69% if litters were mixed at weaning, indicating that farm management measures may affect spread of A. pleuropneumoniae. (C) 2014 Elsevier B.V. All rights reserved.
    Directional movement in response to altered flow in six lowland stream Trichoptera
    Verdonschot, P.F.M. ; Besse, A.A. ; Dekkers, T.B.M. ; Verdonschot, R.C.M. - \ 2014
    Hydrobiologia 740 (2014)1. - ISSN 0018-8158 - p. 219 - 230.
    lotic macroinvertebrates - benthic invertebrates - field experiments - upstream movements - river systems - drift - colonization - habitat - refugia - insect
    Understanding the trait adaptations associated with mobility in Trichoptera larvae under different flow conditions would enhance the understanding of survival mechanisms under flow stress induced by spates. In stream mesocosms, we mimicked a lowland stream spate by suddenly increasing current velocity above an organic habitat patch from 10 to 30 or 50 cm/s. Subsequently, we investigated whether short-term, small-scale movements in six Trichoptera species were not random but directional and whether the type of movement was related to the magnitude of flow increase. Main types of response distinguished were as follows: (1) resistance, in which the species remained in the habitat patch, (2) upstream or downstream crawling, and (3) being dislodged from the streambed and drift downstream (vulnerability). The type of response observed was related to the species’ ecological preferences and morphological traits. The experiment showed that movement in Trichoptera larvae was directional and flow-dependent. Drift was the main mechanism observed with an increase in current velocity, but upstream crawling and aggregation in the habitat patch were observed as well. The type and magnitude of the response were highly species specific. It appeared that each combination of morphological and behavioral adaptations developed individually for each species under niche-specific conditions.
    A SpoT polymorphism correlates with chill stress survival and is prevalent in clinical isolates of Campylobacter jejuni
    Nierop Groot, M.N. ; Boer, A.G. de; Pelt, W. van; Hulst-van Arkel, M.C. van der; Leeuw, P. ; Widjaja, H.C.A. ; Smits, M.A. ; Wal, F.J. van der - \ 2014
    Poultry Science 93 (2014)11. - ISSN 0032-5791 - p. 2900 - 2909.
    virulence-associated phenotypes - htra degp protein - chicken carcasses - escherichia-coli - broiler meat - poultry - colonization - strains - netherlands - expression
    Resistance of Campylobacter jejuni to environmental stress is regarded as a risk factor for the transmission of C. jejuni from poultry or poultry products to humans. So far, the mechanisms underlying the capacity of C. jejuni to survive environmental stress conditions are not fully understood. In this study, we searched for polymorphisms in C. jejuni genes, potentially involved in resistance to chill stress. To this end, we assessed 3 groups of C. jejuni isolates (clinical, retail chicken meat, and feces) for survival of experimentally induced chill stress. For each isolate we sequenced 3 genes encoding the C. jejuni sigma factors FliA, RpoD, and RpoN as well as the genes for the transcriptional regulator SpoT and the periplasmic protein HtrA. Data suggest a higher prevalence of a specific polymorphism in spoT in clinical isolates compared with poultry meat or farm isolates. Moreover, this genotype correlated with enhanced survival of chill stress. The observation that the prevalence of this SNP is relatively high in clinical isolates, which most likely have been exposed to multiple forms of stress, suggest that this SNP may be a biomarker for enhanced survival of stress.
    Genetic variability of central–western European pine marten (Martes martes) populations
    Pertoldi, C. ; Elschot, K. ; Ruiz-Gonzalez, A. ; Zande, L. van de; Zalewski, A. ; Muñoz, J. ; Madsen, A.B. ; Loeschcke, V. ; Groot, G.A. de; Bijlsma, R.J. - \ 2014
    Acta Theriologica 59 (2014)4. - ISSN 0001-7051 - p. 503 - 510.
    mitochondrial-dna variation - glacial refugia - clethrionomys-glareolus - control-region - phylogeography - conservation - consequences - colonization - evolution - patterns
    Recent studies highlighted the potential role of cryptic glacial refugia for temperate taxa in Europe beyond the Mediterranean peninsulas. To further investigate phylogeographic features of the European pine marten (Martes martes) in previously identified cryptic refugia located in central–western Europe, we analysed the hyper-variable diagnostic fragment of the mitochondrial control region in a total of 134 specimens, allowing for reliable comparisons with previous genetic studies of the species. We included samples from eight different European countries in central–western Europe (Belgium, France, Luxembourg and the Netherlands), in south–western Europe (Spain), in north–central Europe (Denmark) and in central Europe (Germany and Poland). The sequences collapsed in 17 haplotypes, which allowed us to determine the genetic composition of the pine marten populations throughout central–western Europe. Overall, our results showed that the population genetic variation, estimated by the standardised haplotype diversity, was high (0.400¿=¿Hs¿=¿0.762), and it was considerably higher in Germany (0.762) and the Netherlands (0.722) compared to the other countries. The nucleotide diversity was relatively low (0.002¿=¿p¿=¿0.016) even in Germany and the Netherlands (0.016 and 0.014, respectively), suggesting relatively small, long-term effective population sizes or severe bottlenecks. Out of the 17 haplotypes found in our study area, 13 were unique and limited to a single country: one in Denmark, one in Spain, four in Poland and seven in the Netherlands. The pairwise genetic distance ranged from 0.001 to 0.032 and did not show any evident correlation with the geographic distances between the populations. A genealogical relationship network was constructed, which provided evidence for a recent origin of many of the unique haplotypes. Approximately 82 % of the samples analysed in this study belonged to haplotypes grouped into a previously identified central–northern European phylogroup of the species. Our results support previous findings, indicating low contribution of southern refugial populations to the postglacial recolonization of central–western Europe and a predominant contribution of pine marten populations that survived the Last Glacial Maxima in cryptic northern refugia.
    Metropolitan Blueprints of Colonial Taxation? Lessons from Fiscal Capacity Building in British and French Africa, c. 1880-1940
    Frankema, E.H.P. ; Waijenburg, M.F.M. van - \ 2014
    Journal of African History 55 (2014)3. - ISSN 0021-8537 - p. 371 - 400.
    sub-saharan africa - growth - education - colonization - institutions - government - legacies - origins - history - world
    The historical and social science literature is divided about the importance of metropolitan blueprints of colonial rule for the development of colonial states. We exploit historical records of colonial state finances to explore the importance of metropolitan identity on the comparative development of fiscal institutions in British and French Africa. Taxes constituted the financial backbone of the colonial state and were vital to the state building efforts of colonial governments. A quantitative comparative perspective shows that pragmatic responses to varying local conditions can easily be mistaken for specific metropolitan blueprints of colonial governance and that under comparable local circumstances the French and British operated in remarkably similar ways.
    The effectiveness of ditch banks as dispersal corridor for plants in agricultural landscapes depends on species' dispersal traits
    Dijk, W.F.A. van; Ruijven, J. van; Berendse, F. ; Snoo, G.R. de - \ 2014
    Biological Conservation 171 (2014). - ISSN 0006-3207 - p. 91 - 98.
    agri-environment schemes - european countries - biodiversity - grassland - farmland - habitat - colonization - fragmentation - connectivity - pollinators
    The effectiveness of agri-environment schemes (AES) in enhancing biodiversity in agricultural landscapes is still strongly debated. In the Netherlands, one of the most widely implemented AES is the management of ditch banks to enhance plant species diversity. Previous research has shown that this type of AES has not led to increases in plant diversity. However, this work also showed that the success of this type of AES may depend on the presence of source populations in the surrounding areas. In this study we investigated if species-rich nature reserves can act as seed sources for agricultural ditch banks under AES and whether this function of nature reserves differs among plant species with different dispersal capacities. We used data collected by farmers over a 10 year period to analyse trends in species richness of target plants and in different dispersal groups in ditch banks under AES at different distances from nature reserves. Our results demonstrate that nature reserves can act as species rich sources in agricultural landscapes and that adjacent AES ditch banks can facilitate the colonisation of the surrounding agricultural landscape. However, the suitability of ditch banks as corridors depends on the dispersal capacity of a species. Particularly water-dispersed species clearly spread from nature reserves into the surrounding agricultural landscape along ditches. In contrast, species without adaptations to disperse over long distances do not show these spatiotemporal patterns.
    Plant movements and climate warming: intraspecific variation in growth responses to nonlocal soils
    Frenne, P. De; Coomes, D. ; Schrijver, A. De; Staelens, J. ; Alexander, J.M. ; Bernhardt-Romermann, M. ; Brunet, J. ; Chabrerie, O. ; Chiarucci, A. ; Ouden, J. den - \ 2014
    New Phytologist 202 (2014)2. - ISSN 0028-646X - p. 431 - 441.
    local adaptation - latitudinal gradient - vascular plants - forest herbs - nitrogen deposition - seed dispersal - range shifts - germination - colonization - temperature
    Most range shift predictions focus on the dispersal phase of the colonization process. Because moving populations experience increasingly dissimilar nonclimatic environmental conditions as they track climate warming, it is also critical to test how individuals originating from contrasting thermal environments can establish in nonlocal sites. We assess the intraspecific variation in growth responses to nonlocal soils by planting a widespread grass of deciduous forests (Milium effusum) into an experimental common garden using combinations of seeds and soil sampled in 22 sites across its distributional range, and reflecting movement scenarios of up to 1600 km. Furthermore, to determine temperature and forest-structural effects, the plants and soils were experimentally warmed and shaded. We found significantly positive effects of the difference between the temperature of the sites of seed and soil collection on growth and seedling emergence rates. Migrant plants might thus encounter increasingly favourable soil conditions while tracking the isotherms towards currently ‘colder’ soils. These effects persisted under experimental warming. Rising temperatures and light availability generally enhanced plant performance. Our results suggest that abiotic and biotic soil characteristics can shape climate change-driven plant movements by affecting growth of nonlocal migrants, a mechanism which should be integrated into predictions of future range shifts.
    Mother-to-Infant Transmission of Intestinal Bifidobacterial Strains Has an Impact on the Early Development of Vaginally Delivered Infant's Microbiota
    Makino, H. ; Kushiro, A. ; Ishikawa, E. ; Kubota, H. ; Gawad, A. ; Sakai, T. ; Oishi, K. ; Martin, R. ; Ben-Amor, K. ; Knol, J. ; Tanaka, R. - \ 2013
    PLoS ONE 8 (2013)11. - ISSN 1932-6203
    species-specific primers - milk oligosaccharides - gut microbiota - fecal flora - bacterial - microflora - colonization - diversity - identification - sequence
    Objectives: Bifidobacterium species are one of the major components of the infant's intestine microbiota. Colonization with bifidobacteria in early infancy is suggested to be important for health in later life. However, information remains limited regarding the source of these microbes. Here, we investigated whether specific strains of bifidobacteria in the maternal intestinal flora are transmitted to their infant's intestine. Materials and Methods: Fecal samples were collected from healthy 17 mother and infant pairs (Vaginal delivery: 12; Cesarean section delivery: 5). Mother's feces were collected twice before delivery. Infant's feces were collected at 0 (meconium), 3, 7, 30, 90 days after birth. Bifidobacteria isolated from feces were genotyped by multilocus sequencing typing, and the transitions of bifidobacteria counts in infant's feces were analyzed by quantitative real-time PCR. Results: Stains belonging to Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium catenulatum, Bifidobacterium longum subsp. longum, and Bifidobacterium pseudocatenulatum, were identified to be monophyletic between mother's and infant's intestine. Eleven out of 12 vaginal delivered infants carried at least one monophyletic strain. The bifidobacterial counts of the species to which the monophyletic strains belong, increased predominantly in the infant's intestine within 3 days after birth. Among infants delivered by C-section, monophyletic strains were not observed. Moreover, the bifidobacterial counts were significantly lower than the vaginal delivered infants until 7 days of age. Conclusions: Among infants born vaginally, several Bifidobacterium strains transmit from the mother and colonize the infant's intestine shortly after birth. Our data suggest that the mother's intestine is an important source for the vaginal delivered infant's intestinal microbiota.
    Explaining Bacterial Dispersion on Leaf Surfaces with an Individual-Based Model (PHYLLOSIM)
    Wal, A. van der; Tecon, R. ; Kreft, J.U. ; Mooij, W.M. ; Leveau, J.H.J. - \ 2013
    PLoS ONE 8 (2013)10. - ISSN 1932-6203
    plant-microbe interactions - pseudomonas-syringae - biofilm formation - water availability - growth - detachment - diffusion - motility - colonization - wettability
    We developed the individual-based model PHYLLOSIM to explain observed variation in the size of bacterial clusters on plant leaf surfaces (the phyllosphere). Specifically, we tested how different 'waterscapes' impacted the diffusion of nutrients from the leaf interior to the surface and the growth of individual bacteria on these nutrients. In the 'null' model or more complex 'patchy' models, the surface was covered with a continuous water film or with water drops of equal or different volumes, respectively. While these models predicted the growth of individual bacterial immigrants into clusters of variable sizes, they were unable to reproduce experimentally derived, previously published patterns of dispersion which were characterized by a much larger variation in cluster sizes and a disproportionate occurrence of clusters consisting of only one or two bacteria. The fit of model predictions to experimental data was about equally poor (
    Diversity patterns of leaf-associated aquatic hyphomycetes along a broad latitudinal gradient
    Jabiol, J. ; Bruder, A. ; Gessner, M.O. ; Makkonen, M. ; McKie, B.G. ; Peeters, E.T.H.M. ; Vos, V.C.A. ; Chauvet, E. - \ 2013
    Fungal Ecology 6 (2013)5. - ISSN 1754-5048 - p. 439 - 448.
    species-diversity - community structure - fungal communities - stream - litter - biodiversity - temperature - leaves - colonization - decomposition
    Information about the global distribution of aquatic hyphomycetes is scarce, despite the primary importance of these fungi in stream ecosystem functioning. In particular, the relationship between their diversity and latitude remains unclear, due to a lack of coordinated surveys across broad latitudinal ranges. This study is a first report on latitudinal patterns of aquatic hyphomycete diversity associated with native leaf-litter species in five streams located along a gradient extending from the subarctic to the tropics. Exposure of leaf litter in mesh bags of three different mesh sizes facilitated assessing the effects of including or excluding different size-classes of litter-consuming invertebrates. Aquatic hyphomycete evenness was notably constant across all sites, whereas species richness and diversity, expressed as the Hill number, reached a maximum at mid-latitudes (Mediterranean and temperate streams). These latitudinal patterns were consistent across litter species, despite a notable influence of litter identity on fungal communities at the local scale. As a result, the bell-shaped distribution of species richness and Hill diversity deviated markedly from the latitudinal patterns of most other groups of organisms. Differences in the body-size distribution of invertebrate communities colonizing the leaves had no effect on aquatic hyphomycete species richness, Hill diversity or evenness, but invertebrates could still influence fungal communities by depleting litter, an effect that was not captured by the design of our experiment. (C) 2013 Elsevier Ltd and The British Mycological Society. All rights reserved.
    From space and from the ground: determining forest dynamics in settlement projects in the Brazilian Amazon
    Diniz, F.H. ; Kok, K. ; Hott, H.C. ; Hoogstra-Klein, M.A. ; Arts, B.J.M. - \ 2013
    International Forestry Review 15 (2013)3. - ISSN 1465-5489 - p. 442 - 455.
    land-use change - secondary forests - ecuadorian amazon - transition theory - deforestation - cover - reforestation - colonization - biodiversity - expansion
    Deforestation in the Brazilian Amazon has been partially attributed to the establishment of settlement projects. Acknowledging the difficulties in quantifying the rate and patterns of deforestation, the objective of this paper is to determine forest dynamics (deforestation and reforestation) in areas where settlement projects have been established, at multiple levels and using different methods. Using satellite images from 1985 to 2010, a study was conducted in five settlement projects in Pará State, aiming to determine forest dynamics at municipal and settlement levels. At property level, participatory maps were constructed to understand settlers’ perception of forest/non-forest areas. The results show that reforestation is the current process in the municipality and in some settlements. Settlers, however, perceive areas with secondary regrowth as potentially fertile cropland and might deforest again in the future. More research is needed to elucidate whether the observed reforestation will lead to a forest transition or is merely a temporary trend.
    Fern spore longevity in saline water: can sea bottom sediments maintain a viable spore bank?
    Groot, G.A. de; During, H. - \ 2013
    PLoS ONE 8 (2013)11. - ISSN 1932-6203 - 11 p.
    genetic diversity - diaspore banks - dispersal - germination - colonization - temperature - populations - ecosystems - plants - nacl
    Freshwater and marine sediments often harbor reservoirs of plant diaspores, from which germination and establishment may occur whenever the sediment falls dry. Therewith, they form valuable records of historical interand intraspecific diversity, and are increasingly exploited to facilitate diversity establishment in new or restored nature areas. Yet, while ferns may constitute a considerable part of a vegetation’s diversity and sediments are known to contain fern spores, little is known about their longevity, which may suffer from inundation and - in sea bottoms - salt stress. We tested the potential of ferns to establish from a sea or lake bottom, using experimental studies on spore survival and gametophyte formation, as well as a spore bank analysis on sediments from a former Dutch inland sea. Our experimental results revealed clear differences among species. For Asplenium scolopendrium and Gymnocarpium dryopteris, spore germination was not affected by inundated storage alone, but decreased with rising salt concentrations. In contrast, for Asplenium trichomanes subsp. quadrivalens germination decreased following inundation, but not in response to salt. Germination rates decreased with time of storage in saline water. Smaller and less viable gametophytes were produced when saline storage lasted for a year. Effects on germination and gametophyte development clearly differed among genotypes of A. scolopendrium. Spore bank analyses detected no viable spores in marine sediment layers. Only two very small gametophytes (identified as Thelypteris palustris via DNA barcoding) emerged from freshwater sediments. Both died before maturation. We conclude that marine, and likely even freshwater sediments, will generally be of little value for long-term storage of fern diversity. The development of any fern vegetation on a former sea floor will depend heavily on the deposition of spores onto the drained land by natural or artificial means of dispersal.
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