1,623 research outputs found
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The utility of height for the Ediacaran organisms of Mistaken Point.
Ediacaran fossil communities consist of the oldest macroscopic eukaryotic organisms. Increased size (height) is hypothesized to be driven by competition for water column resources, leading to vertical/epifaunal tiering and morphological innovations such as stems. Using spatial analyses, we find no correlation between tiering and resource competition, and that stemmed organisms are not tiered. Instead, we find that height is correlated with greater offspring dispersal, demonstrating the importance of colonization potential over resource competition.Gibbs Travelling Fellowship from Newnham College, University of Cambridge Henslow Research Fellowship, Cambridge Philosophical Society
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Mortality, Population and Community Dynamics of the Glass Sponge Dominated Community âThe Forest of the Weirdâ From the Ridge Seamount, Johnston Atoll, Pacific Ocean
The ecosystem dynamics of benthic communities depend on the relative importance of organism reproductive traits, environmental factors, inter-specific interactions, and mortality processes. The fine-scale community ecology of sessile organisms can be investigated using spatial analyses because the position of the specimens on the substrate (their spatial positions) reflects the biological and ecological processes that they were subject to in-life. Consequently, spatial point process analyses (SPPA) and Bayesian network inference (BNI) can be used to reveal key insights into the ecological dynamics of these deep-sea communities. Here we use these analyses to investigate the ecology of deep-sea glass sponge dominated community âThe Forest of the Weirdâ (2,442 m depth, Ridge Seamount, Johnston Atoll, Pacific Ocean). A 3D reconstruction was made of this community using photogrammetry of video stills taken from high-resolution ROV video. The community was dominated by two genera of Hexactinellids: Farreidae Aspidoscopulia sp. and Euplectellidae Advhena magnifica with octocorals Narella bowersi, Narella macrocalyx, and Rhodaniridogorgia also present in large proportions. SPPA of the dead vs. alive organisms revealed a random distribution of dead amongst the living, showing a non-density dependent cause of death for the majority of taxa. However, in the high-density ridge crest region there was non-random aggregation of dead specimens, revealing density-dependent mortality for Aspidoscopulia. SPPA showed that the glass sponges and octocorals were each most strongly influenced by different underlying processes, and reacted to the environmental conditions differently. The octocorals responded to higher density areas with increased intra-specific competition, whilst the glass-sponges seemed impervious to a doubling of specimen density. BNI found that mutual habitat associations between different taxa resulted in inter-specific competition at larger (2â4 m) spatial scales, with instances of competition at small-spatial scales (<0.75 m) in the higher-density ridge crest section. To our knowledge, this study is the first to analyze the mortality, population and community dynamics of a deep-sea sponge community using SPPA. Our results provide the first insight into the variety of ecological behaviors of these different glass sponges and octocorals, and show how these different organisms have developed diverse responses to the biological and environmental gradients within their habitat
Out Online: The Experiences of Lesbian, Gay, Bisexual and Transgender Youth on the Internet
This report examines the online experiences of LGBT students in 6-12th grade. LGBT youth experience nearly three times as much bullying and harassment online as non-LGBT youth, but also find greater peer support, access to health information and opportunities to be civically engaged
Risk of Organism Acquisition From Prior Room Occupants: A Systematic Review and Meta-Analysis
A systematic review and meta-analysis was conducted to determine the risk of pathogen acquisition for patients associated with prior room occupancy. The analysis was also broadened to examine any differences in acquisition risk between Gram-positive and Gramânegative organisms
Quantitative Approaches to Understanding Ediacaran Ecology
Ediacaran macrofossils occupy a crucial position in the history of life on Earth, marking the transition between the microbially dominated Proterozoic and the Cambrian explosion of modern animals. These Ediacaran organisms diïŹer fundamentally from those found in other time periods, making it diïŹcult to resolve their phylogenetic relationships or even their basic ecology. Bedding surfaces at Mistaken Point, SE Newfoundland preserve what appear to be entire in-situ communities of Ediacaran (565 Ma) macrofossils under a series of volcanic ash ïŹows. In this dissertation I employ statistical and modelling techniques to investigate the ecological interactions of these problematic organisms with each other and with their environment, in order to test hypotheses about their ecology
Operating at the extreme: Estimating the upper yield boundary of winter wheat production in commercial practice
© 2020 The Authors. Wheat farming provides 28.5% of global cereal production. After steady growth in average crop yield from 1950 to 1990, wheat yields have generally stagnated, which prompts the question of whether further improvements are possible. Statistical studies of agronomic parameters such as crop yield have so far exclusively focused on estimating parameters describing the whole of the data, rather than the highest yields specifically. These indicators include the mean or median yield of a crop, or finding the combinations of agronomic traits that are correlated with increasing average yields. In this paper, we take an alternative approach and consider high yields only. We carry out an extreme value analysis of winter wheat yield data collected in England and Wales between 2006 and 2015. This analysis suggests that, under current climate and growing conditions, there is indeed a finite upper bound for winter wheat yield, whose value we estimate to be 17.60 tonnes per hectare. We then refine the analysis for strata defined by either location or level of use of agricultural inputs. We find that there is no statistical evidence for variation of maximal yield depending on location, and neither is there statistical evidence that maximum yield levels are improved by high levels of crop protection and fertilizer use
Spatial analyses of Ediacaran communities at Mistaken Point
Bedding-plane assemblages of Ediacaran fossils from Mistaken Point, Newfoundland, are among the oldest known records of complex multicellular life on Earth (dated to ~565 Ma). The in situ preservation of these sessile but otherwise deeply enigmatic organisms means that statistical analyses of specimen positions can be used to illuminate their underlying ecological dynamics, including the interactions between taxa.
Fossil assemblages on Mistaken Point D and E surfaces were mapped to millimeter accuracy using differentiated GPS. Spatial correlations between 10 well-defined taxa (Bradgatia, Charniid, Charniodiscus, Fractofusus, Ivesheadiomorphs, Lobate Discs, Pectinifrons, Plumeropriscum, Hiemalora, and Thectardis) were identified using Bayesian network inference (BNI), and then described and analyzed using spatial point-process analysis. BNI found that the E-surface community had a complex web of interactions and associations between taxa, with all but one taxon (Thectardis) interacting with at least one other. The unique spatial distribution of Thectardis supports previous, morphology-based arguments for its fundamentally distinct nature. BNI revealed that the D-surface community showed no interspecific interactions or associations, a pattern consistent with a homogeneous environment.
On the E surface, all six of the abundant taxonomic groups (Fractofusus, Bradgatia, Charniid, Charniodiscus, Thectardis, and Plumeropriscum) were found to have a unique set of interactions with other taxa, reflecting a broad range of underlying ecological responses. Four instances of habitat associations were detected between taxa, of which two (CharniodiscusâPlumeropriscum and PlumeropriscumâFractofusus) led to weak competition for resources. One case of preemptive competition between Charniid and Lobate Discs was detected. There were no instances of interspecific facilitation. Ivesheadiomorph interactions mirror those of Fractofusus and Charniodiscus, identifying them as a form-taxonomic grouping of degradationally homogenized taphomorphs. The absence of increased fossil abundance in proximity to these taphomorphs argues against scavenging or saprophytic behaviors dominating the E-surface community
Facilitating corals in an early Silurian deepâwater assemblage
Corals are powerful ecosystem engineers and can form reef communities with extraordinary biodiversity through time. Understanding the processes underlying the spatial distribution of corals allows us to identify the key biological and physical processes that structure coral communities and how these processes and interactions have evolved. However, few spatial ecology studies have been conducted on coral assemblages in the fossil record. Here we use spatial point process analysis (SPPA) to investigate the ecological interactions of an in situ tabulate and rugose coral community (n = 199), preserved under volcanic ash in the Silurian of Ireland. SPPA is able to identify many different sorts of interactions including dispersal limitation and competition within and between taxa. Our SPPA found that the spatial distribution of rugose corals were best modelled by Thomas clusters (pd = 0.834), indicating a single dispersal episode and that the tabulate corals were best modelled by double Thomas clusters (pd = 0.820), indicating two dispersal episodes. Further, the bivariate distribution was best modelled by linked double clusters (pd = 0.970), giving significant evidence of facilitation between the tabulate and rugose populations, and identifying the facilitators in this community to be the tabulate corals. This interaction could be an important ecological driver for enabling the aggregation of sessile organisms over long temporal periods and facilitation may help to explain trends in reef diversity and abundance during the Ordovician biodiversification and in the early Silurian
Mindfulness-Based Interventions in Recurrent Ovarian Cancer: A Mixed-Methods Feasibility Study.
A recurrence of cancer is a traumatic and stressful experience, and a number of approaches have been proposed to manage or treat the associated psychological distress. Meditative techniques such as mindfulness may be able to improve an individual's ability to cope with stressful life events such as cancer diagnosis or treatment. This single-arm mixed-methods study primarily aimed to determine the feasibility of using a mindfulness-based intervention in managing psychosocial distress in recurrent ovarian cancer. Twenty-eight participants took part in a mindfulness-based program, involving six group sessions, each lasting 1.5 hours and delivered at weekly intervals. The study found that the mindfulness-based intervention was acceptable to women with recurrent ovarian cancer and feasible to deliver within a standard cancer care pathway in a UK hospital setting. The results suggested a positive impact on symptoms of depression and anxiety, but further study is needed to explore the effectiveness of the intervention
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Benthic ecosystem cascade effects in Antarctica using Bayesian network inference
Funder: British Antarctic Survey Polar Science for Planet Earth Programme.Abstract: Antarctic sea-floor communities are unique, and more closely resemble those of the Palaeozoic than equivalent contemporary habitats. However, comparatively little is known about the processes that structure these communities or how they might respond to anthropogenic change. In order to investigate likely consequences of a decline or removal of key taxa on community dynamics we use Bayesian network inference to reconstruct ecological networks and infer changes of taxon removal. Here we show that sponges have the greatest influence on the dynamics of the Antarctic benthos. When we removed sponges from the network, the abundances of all major taxa reduced by a mean of 42%, significantly more than changes of substrate. To our knowledge, this study is the first to demonstrate the cascade effects of removing key ecosystem structuring organisms from statistical analyses of Antarctica data and demonstrates the importance of considering the community dynamics when planning ecosystem management
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