The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Steven Goodman - One of the best experts on this subject based on the ideXlab platform.
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Biogeography of Leptospira in wild Animal Communities inhabiting the insular ecosystem of the western Indian Ocean islands and neighboring Africa
Emerging microbes & infections, 2018Co-Authors: Muriel Dietrich, Yann Gomard, Erwan Lagadec, Beza Ramasindrazana, Gildas Le Minter, Vanina Guernier, Aude Benlali, Gérard Rocamora, Wanda Markotter, Steven GoodmanAbstract:Understanding the processes driving parasite assemblages is particularly important in the context of zoonotic infectious diseases. Leptospirosis is a widespread zoonotic bacterial infection caused by pathogenic species of the genus Leptospira. Despite a wide range of Animal hosts, information is still lacking on the factors shaping Leptospira diversity in wild Animal Communities, especially in regions, such as tropical insular ecosystems, with high host species richness and complex biogeographical patterns. Using a large dataset (34 mammal species) and a multilocus approach at a regional scale, we analyzed the role of both host species diversity and geography in Leptospira genetic diversity in terrestrial small mammals (rodents, tenrecs, and shrews) and bats from 10 different islands/countries in the western Indian Ocean (WIO) and neighboring Africa. At least four Leptospira spp. (L. interrogans, L. borgpetersenii, L. kirschneri, and L. mayottensis) and several yet-unidentified genetic clades contributed to a remarkable regional Leptospira diversity, which was generally related to the local occurrence of the host species rather than the geography. In addition, the genetic structure patterns varied between Leptospira spp., suggesting different evolutionary histories in the region, which might reflect both in situ diversification of native mammals (for L. borgpetersenii) and the more recent introduction of non-native host species (for L. interrogans). Our data also suggested that host shifts occurred between bats and rodents, but further investigations are needed to determine how host ecology may influence these events.
Stefan Scheu - One of the best experts on this subject based on the ideXlab platform.
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Diversity and functional structure of soil Animal Communities suggest soil Animal food webs to be buffered against changes in forest land use
Oecologia, 2021Co-Authors: Melanie M. Pollierer, Mark Maraun, Bernhard Klarner, David Ott, Christoph Digel, Roswitha B. Ehnes, Bernhard Eitzinger, Georgia Erdmann, Ulrich Brose, Stefan ScheuAbstract:Forest soil and litter is inhabited by a diverse community of Animals, which directly and indirectly rely on dead organic matter as habitat and food resource. However, community composition may be driven by biotic or abiotic forces, and these vary with changes in habitat structure and resource supply associated with forest land use. To evaluate these changes, we compiled comprehensive data on the species composition of soil Animal Communities and environmental factors in forest types varying in land-use intensity in each of three regions in Germany, i.e., coniferous, young managed, old managed, and unmanaged beech forests. Coniferous forests featured high amounts of leaf litter and low microbial biomass concentrations contrasting in particular unmanaged beech forests. However, soil Animal diversity and functional community composition differed little between forest types, indicating resilience against disturbance and forest land use. Structural equation modelling suggested that despite a significant influence of forest management on resource abundance and quality, the biomass of most soil fauna functional groups was not directly affected by forest management or resource abundance/quality, potentially because microorganisms hamper the propagation of nutrients to higher trophic levels. Instead, detritivore biomass depended heavily on soil pH. Macrofauna decomposers thrived at high pH, whereas mesofauna decomposers benefitted from low soil pH, but also from low biomass of macrofauna decomposers, potentially due to habitat modification by macrofauna decomposers. The strong influence of soil pH shows that decomposer Communities are structured predominantly by regional abiotic factors exceeding the role of local biotic factors such as forest type.
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roots mycorrhizal fungi and altitude as determinants of litter decomposition and soil Animal Communities in tropical montane rainforests
Plant and Soil, 2019Co-Authors: Franca Marian, Mark Maraun, Linda Brown, Dorothee Sandmann, Stefan ScheuAbstract:This study assesses the importance of root- and mycorrhiza-derived resources for decomposition processes and as food resources for microarthropod Communities along an altitudinal gradient of tropical montane rainforests in southern Ecuador. At 1000, 2000 and 3000 m microcosms with openings of different mesh sizes (4 mm, 45 μm) or closed were exposed in the field, manipulating accessibility by roots and mycorrhizal fungi. The microcosms contained undisturbed soil with a mixture of leaf litter from three abundant plant species from the site at which the microcosms were exposed. After 12 months water content, microbial biomass, remaining litter mass, C-to-N ratio and the soil microarthropod community structure were analysed. Water content and C-to-N ratio were lower and microbial biomass was highest at the lowest altitude, while litter decomposition and microarthropod abundance were at a maximum at the intermediate altitude. Exclusion of roots and mycorrhizal fungi did not affect litter decomposition, but decreased the abundance and diversity of Oribatida, while the abundance of Collembola increased in closed microcosms. The effect of root and mycorrhizal exclusion on all investigated parameters did not differ between the three altitudes. The results indicate that in nutrient limited tropical montane rainforests mycorrhizal fungi suppress the activity of other microorganisms, potentially competing for litter-derived resources, at each of the investigated altitudes. Collembola benefitted from this reduced competition while Oribatida strongly depended on root-derived resources.
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trophic guilds of generalist feeders in soil Animal Communities as indicated by stable isotope analysis 15n 14n
Bulletin of Entomological Research, 2010Co-Authors: Katja Oelbermann, Stefan ScheuAbstract:We investigated if the commonly used aggregation of organisms into trophic guilds, such as detritivores and predators, in fact represent distinct trophic levels. Soil arthropods of a forest-meadow transect were ascribed a priori to trophic guilds (herbivores, detritivores, predators and necrovores), which are often used as an equivalent to trophic levels. We analysed natural variations in 15N/14N ratios of the Animals in order to investigate the trophic similarity of organisms within (a priori defined) trophic guilds. Using trophic guilds as an equivalent to trophic level, the assumed stepwise enrichment of 15N by 3.4 per thousand per trophic level did not apply to detritivores; they were only enriched in 15N by on average 1.5 per thousand compared to litter materials. Predators on average were enriched in 15N by 3.5 per thousand compared to detritivores. Within detritvores and predators delta15N signatures varied markedly, indicating that these trophic guilds are dominated by generalist feeders which form a gradient of organisms feeding on different resources. The results indicate that commonly used trophic guilds, in particular detritivores and predators, do not represent trophic levels but consist of subguilds, i.e. subsets of organisms differing in resource utilization. In particular, in soil and litter food webs where trophic level omnivory is common, the use of distinct trophic levels may be inappropriate. Guilds of species delineated by natural variations of stable isotope ratios are assumed to more adequately represent the structure of litter and soil food webs allowing a more detailed understanding of their functioning.
Sean J Doody - One of the best experts on this subject based on the ideXlab platform.
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chronic effects of an invasive species on an Animal community
Ecology, 2017Co-Authors: Sean J Doody, David Rhind, Brian Green, Christina M Castellano, Colin Mchenry, Simon ClulowAbstract:Invasive species can trigger trophic cascades in Animal Communities, but published cases involving their removal of top predators are extremely rare. An exception is the invasive cane toad (Rhinella marina) in Australia, which has caused severe population declines in monitor lizards, triggering trophic cascades that facilitated dramatic and sometimes unexpected increases in several prey of the predators, including smaller lizards, snakes, turtles, crocodiles, and birds. Persistence of isolated populations of these predators with a decades-long sympatry with toads suggests the possibility of recovery, but alternative explanations are possible. Confirming predator recovery requires longer-term study of populations with both baseline and immediate post-invasion densities. Previously, we quantified short-term impacts of invasive cane toads on Animal Communities over seven years at two sites in tropical Australia. Herein we test the hypothesis that predators have begun to recover by repeating the study 12 years after the initial toad invasion. The three predatory lizards that experienced 71-97% declines in the short-term study showed no sign of recovery, and indeed a worse fate; two of the three species were no longer detectable in 630 km of river surveys, suggesting local extirpation. Two mesopredators that had increased markedly in the short-term due to the above predator losses showed diverse responses in the medium-term; a small lizard species increased by ca. 500%, while populations of a snake species showed little change. Our results indicate a system still in ecological turmoil, having not yet reached a ‘new equilibrium’ more than a decade after the initial invasion; predator losses due to this toxic invasive species, and thus downstream effects, were not transient. Given that cane toads have proven too prolific to eradicate or control, we suggest that recovery of impacted predators must occur unassisted by evolutionary means: dispersal into extinction sites from surviving populations with alleles for toxin resistance or toad avoidance. Evolution and subsequent dispersal may be the only solution for a number of species or Communities affected by invasive species for which control is either prohibitively expensive, or not possible. This article is protected by copyright. All rights reserved.
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invasive toads shift predator prey densities in Animal Communities by removing top predators
Ecology, 2015Co-Authors: Sean J Doody, David Rhind, Brian Green, Christina M Castellano, Rebekah Soanes, Colin R Mchenry, Simon ClulowAbstract:Although invasive species can have substantial impacts on Animal Communities, cases of invasive species facilitating native species by removing their predators have rarely been demonstrated across vertebrate trophic linkages. The predictable spread of the invasive cane toad (Rhinella marina), however, offered a unique opportunity to quantify cascading effects. In northern Australia, three species of predatory monitor lizards suffered severe population declines due to toad-induced lethal toxic ingestion (yellow-spotted monitor (Varanus panoptes), Mertens' water monitor (V. mertensi), Mitchell's water monitor (V. mitchelli). We, thus, predicted subsequent increases in the abundance and recruitment of prey species due to the reduction of those predators. Toad-induced population-level declines in the water monitor species approached 50% over a five-year period spanning the toad invasion, apparently causing fledging success of the Crimson Finch (Neochmia.phaeton) to increase from 55% to 81%. The consensus of our original and published long-term data is that invasive cane toads are causing predators to lose a foothold on top-down regulation of their prey, triggering shifts in the relative densities of predator and prey in the Australian tropical savannah ecosystem.
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the dry season shuffle gorges provide refugia for Animal Communities in tropical savannah ecosystems
PLOS ONE, 2015Co-Authors: Sean J Doody, David Rhind, Christina M Castellano, Simon Clulow, Geoff Kay, Domenic C Damore, Steve Wilson, Ryan J Ellis, Colin R MchenryAbstract:In the wet-dry tropics, Animal species face the major challenges of acquiring food, water or shelter during an extended dry season. Although large and conspicuous Animals such as ungulates and waterfowl migrate to wetter areas during this time, little is known of how smaller and more cryptic Animal species with less mobility meet these challenges. We fenced off the entire entrance of a gorge in the Australian tropical savanna, offering the unique opportunity to determine the composition and seasonal movement patterns of the small vertebrate community. The 1.7 km-long fence was converted to a trapline that was deployed for 18-21 days during the early dry season in each of two years, and paired traps on both sides of the fence allowed us to detect the direction of Animal movements. We predicted that semi-aquatic species (e.g., frogs and turtles) would move upstream into the wetter gorge during the dry season, while more terrestrial species (e.g., lizards, snakes, mammals) would not. The trapline captured 1590 individual vertebrates comprising 60 species. There was a significant bias for captures on the outside of the fence compared to the inside for all species combined (outside/inside = 5.2, CI = 3.7-7.2), for all vertebrate classes, and for specific taxonomic groups. The opposite bias (inside/outside = 7.3, N= 25) for turtles during the early wet season suggested return migration heading into the wet season. Our study revealed that the small vertebrate community uses the gorge as a dry season refuge. The generality of this unreplicated finding could be tested by extending this type of survey to tropical savannahs worldwide. A better understanding of how small Animals use the landscape is needed to reveal the size of buffer zones around wetlands required to protect both semi-aquatic and terrestrial fauna in gorges in tropical savannah woodland, and thus in ecosystems in general.
Koki Horikoshi - One of the best experts on this subject based on the ideXlab platform.
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psychromonas kaikoae sp nov a novel piezophilic bacterium from the deepest cold seep sediments in the japan trench
International Journal of Systematic and Evolutionary Microbiology, 2002Co-Authors: Yuichi Nogi, Chiaki Kato, Koki HorikoshiAbstract:Two strains of obligately piezophilic bacteria were isolated from sediment collected from the deepest cold-seep environment with chemosynthesis-based Animal Communities within the Japan Trench, at a depth of 7434 m. The isolated strains, JT7301 and JT7304 T , were closely affiliated with members of the genus Psychromonas on the basis of 16S rDNA sequence analysis. Hybridization values for DNA-DNA relatedness between these strains and the Psychromonas antarctica reference strain were significantly lower than that accepted as the phylogenetic definition of a species. The optimal temperature and pressure for growth of the isolates were 10 °C and 50 MPa and they produced both eicosapentaenoic acid (C20:5ω3) and docosahexaenoic acid (C22:6) in the membrane layer. Based on the taxonomic differences observed, the isolated strains appear to represent a novel obligately piezophilic Psychromonas species. The name Psychromonas kaikoae sp. nov. (type strain JT7304 T = JCM 11054 T = ATCC BAA-363 T ) is proposed. This is the first proposed obligately piezophilic species of the genus Psychromonas.
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psychromonas kaikoae sp nov a novel from the deepest piezophilic bacterium cold seep sediments in the japan trench
International Journal of Systematic and Evolutionary Microbiology, 2002Co-Authors: Yuichi Nogi, Chiaki Kato, Koki HorikoshiAbstract:Two strains of obligately piezophilic bacteria were isolated from sediment collected from the deepest cold-seep environment with chemosynthesis-based Animal Communities within the Japan Trench, at a depth of 7434 m. The isolated strains, JT7301 and JT7304T, were closely affiliated with members of the genus Psychromonas on the basis of 16S rDNA sequence analysis. Hybridization values for DNA-DNA relatedness between these strains and the Psychromonas antarctica reference strain were significantly lower than that accepted as the phylogenetic definition of a species. The optimal temperature and pressure for growth of the isolates were 10 degrees C and 50 MPa and they produced both eicosapentaenoic acid (C20:5omega3) and docosahexaenoic acid (C22:6) in the membrane layer. Based on the taxonomic differences observed, the isolated strains appear to represent a novel obligately piezophilic Psychromonas species. The name Psychromonas kaikoae sp. nov. (type strain JT7304T = JCM 11054T = ATCC BAA-363T) is proposed. This is the first proposed obligately piezophilic species of the genus Psychromonas.
Tancredi Caruso - One of the best experts on this subject based on the ideXlab platform.
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population asynchrony alone does not explain stability in species rich soil Animal assemblages the stabilizing role of forest age on oribatid mite Communities
Journal of Animal Ecology, 2020Co-Authors: Tancredi Caruso, Viesturs Melecis, Ugis Kagainis, Thomas BolgerAbstract:The importance of microbial and plant Communities in the control of the diversity and structure of soil Animal Communities has been clarified over the last decade. Previous research focused on abiotic factors, niche separation and spatial patterns. Significant gaps still exist in our knowledge of the factors that control the stability of these Communities over time. We analysed a 9-year dataset from the national Long-term Ecological Research Network of Latvia. We focused on 117 oribatid species from three Scots pine forests of different age ( 150 years) and structure. For each forest type, 100 samples were collected each year, providing very high replication and long time series for a soil community. We assessed different aspects of stability: we used a dynamic null model, parameterized on observed growth rates, to test the hypothesis that asynchrony in species populations stabilizes total community size; we also analysed alpha and beta diversity over time to test the hypothesis that temporal variation in species composition and relative abundances is controlled by forest attributes. Real Communities can be more stable than their stochastic counterparts if species are asynchronous, confirming for the first time the role of asynchrony in stabilizing soil Communities. Yet, while some real Communities were more stable and had higher abundance and growth rates than others, they were not necessarily more asynchronous than the less stable Communities. Species composition and relative abundances were also less variable in the more stable Communities. Species asynchrony generally stabilizes species-rich Communities but is not sufficient to explain the different levels of stability between forests. Forest age is a key factor explaining the different levels of overyielding and so stability. Data suggest that both asynchrony and high diversity of microhabitat structure of Scots pine forests promote the stability of soil Animal Communities.
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Oribatid mites reveal that competition for resources and trophic structure combine to regulate the assembly of diverse soil Animal Communities.
Ecology and Evolution, 2019Co-Authors: Matthew Magilton, Mark Maraun, Mark Emmerson, Tancredi CarusoAbstract:: The role of niche partitioning in structuring species-rich soil Animal Communities has been debated for decades and generated the "enigma of soil Animal diversity." More recently, resource-based niche partitioning has been hypothesized to play a very limited role in the assembly of soil Animal Communities. To test this hypothesis, we applied a novel combination of stable isotopes and null models of species co-occurrence to quantify the extent of resource niche partitioning on a diverse oribatid mite community sampled from mature oak woodland.We asked whether species aggregate or segregate spatially and how these patterns correlated with the abundance of estimated trophic guilds. We also estimated the effects of environmental variables on community structure.All measured environmental variables accounted for 12% of variance in community structure, including 8% of pure spatial structure unrelated to measured environmental factors and 2% of pure environmental variance unrelated to spatial variation. Co-occurrence analysis revealed 10 pairs of species that aggregated and six pairs of species that were spatially segregated. Values of δ15N indicated that five out of the 10 pairs of aggregated species occupied the same trophic guild, while values of δ13C indicated that species in these five pairs consumed resources of different quality, supporting a significant role of resource-based niche partitioning. Also, one of the five pairs of segregated species occupied the same trophic guild but had overlapping δ13C values suggesting that these species do not co-occur locally and thus minimize competition for shared resources.Partitioning of resources plays an underestimated role in soil microarthropod Communities and different local Communities consisted of the same trophic guilds with species identity changing from place to place. The sum of resource partitioning, multi-trophic interactions, and microscale environmental variability in the environment is a viable solution to the enigma of soil Animal diversity.