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As the higher education landscape has shifted and calls for change and improvements have grown louder, researchers have turned to empirical investigations of what makes change possible in higher education. Recent studies on the impact of informal interactions for promoting change have given impetus to social network analysis as an approach to studying higher education change. However, the relationship between teachers’ social network characteristics and their disposition to adopt changes remains largely unknown. In this study, we describe the characteristics of teaching networks and explain the network characteristics of the most innovative teaching staff. By capturing whole teaching and research networks within a STEM discipline department at a Norwegian university, we show that teachers tend to speak to the same colleagues about both research and teaching, and that teaching communities are constrained by departmental sub-units (i.e. research groups). Furthermore, by combining the network data with a survey on diffusion of innovation, we find that the most innovative teachers (1) are central in the network, having the largest personal networks, (2) have a substantial reach to the rest of the network, and (3) are highly interconnected. This paper contributes to the understanding of change theories in higher education and discusses how these results can inform the practice of change agents and educational developers. In addition to confirming the presence of a research-teaching nexus, we discuss why leveraging the networks of the most innovative teaching staff would be a promising strategy for facilitating change in higher education. [ABSTRACT FROM AUTHOR]

Abstract: As custodians of deep time, palaeontologists have an obligation to seek the causes and consequences of long‐term evolutionary trajectories and the processes of ecosystem assembly and collapse. Building explicit process models on the relevant scales can be fraught with difficulties, and causal inference is typically limited to patterns of association. In this review, we discuss some of the ways in which causal connections can be extracted from palaeontological time series and provide an overview of three recently developed analytical frameworks that have been applied to palaeontological questions, namely linear stochastic differential equations, convergent cross mapping and transfer entropy. We outline how these methods differ conceptually, and in practice, and point to available software and worked examples. We end by discussing why a paradigm of dynamical causality is needed to decipher the messages encrypted in palaeontological patterns. [ABSTRACT FROM AUTHOR]

The fossil record is a unique resource on the history of life, but it is well known to be incomplete. In a series of high-profile papers, a residual modelling technique has been applied to correct the raw palaeodiversity signal for this bias and incompleteness, and the claim is made that the processed time series are more accurate than the raw data. We apply empirical and simulation approaches to test for correlation and directionality of any relationships between rock and fossil data. The empirical data comprise samples of the global fossil record through the Phanerozoic, and we use simulations to assess whether randomly sampled subsets of modelled data can be improved by application of the residual modelling technique. Our results show that using formation counts as a sampling proxy to correct the fossil record via residual modelling is ill founded. The supposedly independent model of sampling is information-redundant with respect to the raw palaeodiversity data it seeks to correct, and so the outputs are generally likely to be further from the truth than the raw data. We recommend that students of palaeodiversity cease to use residual modelling estimates based on formation counts, and suggest that results from a substantial number of papers published in the past ten years require re-evaluation. [ABSTRACT FROM AUTHOR]

Common species shape the world around us, and changes in their commonness signify large-scale shifts in ecosystem structure and function. However, our understanding of long-term ecosystem response to environmental forcing in the deep past is centred on species richness, neglecting the disproportional impact of common species. Here, we use common and widespread species of planktonic foraminifera in deep-sea sediments to track changes in observed global occupancy (proportion of sampled sites at which a species is present and observed) through the turbulent climatic history of the last 65 Myr. Our approach is sensitive to relative changes in global abundance of the species set and robust to factors that bias richness estimators. Using three independent methods for detecting causality, we show that the observed global occupancy of planktonic foraminifera has been dynamically coupled to past oceanographic changes captured in deep-ocean temperature reconstructions. The causal inference does not imply a direct mechanism, but is consistent with an indirect, time-delayed causal linkage. Given the strong quantitative evidence that a dynamical coupling exists, we hypothesize that mixotrophy (symbiont hosting) may be an ecological factor linking the global abundance of planktonic foraminifera to long-term climate changes via the relative extent of oligotrophic oceans. [ABSTRACT FROM AUTHOR]

Calcifying phytoplankton play an important role in marine ecosystems and global biogeochemical cycles, affecting the transfer of both organic and inorganic carbon from the surface to the deep ocean. Coccolithophores are the most prominent members of this group, being well adapted to low-nutrients environments (e.g., subtropical gyres). Despite urgent concerns, their response to rising atmospheric carbon dioxide levels ( p CO2) and ocean acidification is still poorly understood, and short-term experiments may not extrapolate into longer-term climatic adaptation. Current atmospheric p CO2 (~390 ppmv) is unprecedented since at least 3 million years ago (Ma), and levels projected for the next century were last seen more than 34 Ma. Hence, a deep-time perspective is needed to understand the long-term effects of high p CO2 on the biosphere. Here we combine a comprehensive fossil data set on coccolithophore cell size with a novel measure of ecological prominence: Summed Common Species Occurrence Rate ( SCOR). The SCOR is decoupled from species richness, and captures changes in the extent to which coccolithophores were common and widespread, based on global occurrences in deep-sea sediments. The size and SCOR records are compared to state-of-the-art data on climatic and environmental changes from 50 to 5 Ma. We advance beyond simple correlations and trends to quantify the relative strength and directionality of information transfer among these records. Coccolithophores were globally more common and widespread, larger, and more heavily calcified in the pre-34 Ma greenhouse world, and declined along with p CO2 during the Oligocene (34-23 Ma). Our results suggest that atmospheric p CO2 has exerted an important long-term control on coccolithophores, directly through its availability for photosynthesis or indirectly via weathering supply of resources for growth and calcification. [ABSTRACT FROM AUTHOR]

The Phanerozoic fossil record of marine animal diversity covaries with the amount of marine sedimentary rock. The extent to which this covariation reflects a geologically controlled sampling bias remains unknown. We show that Phanerozoic records of seawater chemistry and continental flooding contain information on the diversity of marine animals that is independent of sedimentary rock quantity and sampling. Interrelationships among variables suggest long-term interactions among continental flooding, sulfur and carbon cycling, and macroevolution. Thus, mutual responses to interacting Earth systems, not sampling biases, explain much of the observed covariation between Phanerozoic patterns of sedimentation and fossil biodiversity. Linkages between biodiversity and environmental records likely reflect complex biotic responses to changing ocean redox conditions and long-term sea-level fluctuations driven by plate tectonics. [ABSTRACT FROM AUTHOR]

Quantitative characterization of the mode and rate of phenotypic evolution is rarely applied to prokaryotes. Here, we present an analysis of temperature optimum ( T) evolution in the thermophilic family Thermotogaceae, which has a large number of cultured representatives. We use log-rate-interval analysis to show that T evolution in Thermotogaceae is consistent with a Brownian motion (BM) evolutionary model. The properties of the BM model are used to a establish confidence intervals on the unknown phenotypic trait value of an uncultured organism, given its distance to a close relative with known trait value. Cross-validation by bootstrapping indicates that the predictions are robust. [ABSTRACT FROM AUTHOR]

Quantification of drive-response relationships from geological records is challenged both by the complexity of the interactions and by indirect and uncertain proxy data. Here I demonstrate the use of information-theoretic techniques to detect causal relationships directly from incomplete and noisy time series. A non-parametric estimate of information transfer (IT) is used to quantify (1) the relative strength of statistical dependence among three variables, including nonlinear relationships, and (2) the directionality of coupling between two variables, compared to surrogate time series. Surrogates preserve the amplitudes and frequencies of the original data, and allow causation to be distinguished from correlation. Simple data pre-processing helps overcome biases related to non-stationarity. Causal inference involves a combination of the two IT calculations, and the method is sufficiently robust to sparse, irregular sampling to have geological applicability. Two case studies highlight some of the possibilities and limitations: (1) IT analysis of oxygen isotope records from Chinese speleothems against ice cores from Greenland and Antarctica suggests time-varying relative influence of the two hemispheres on monsoon intensity over the interval 40 to 10 Ka. IT from the Greenland record dominates except in the deep glacial phase, during which IT from the Antarctic record is more prominent. (2) IT analyses of Phanerozoic seawater isotope ratios capture long-term coupling between temperature (δ18O) and carbon cycling (δ13C), and between the cycling of carbon (δ13C) and sulfur (δ34S). Results suggest that the δ34S record contains an important signal for understanding Phanerozoic Earth system evolution. Although directional IT between proxies cannot be equated with direct causality, the method holds some promise as a data-driven approach to inferring causal interactions from geological records. [ABSTRACT FROM AUTHOR]

Spatial and temporal patterns in the sedimentary record are controlled by a wide range of forcing mechanisms. Macrostratigraphy uses the temporal ranges of gap-bound rock packages, compiled separately for different geographic locations, to quantify these patterns. The total number of gap-bound packages (D) and the rates of package initiation and truncation (p and q, respectively) distill depositional geometries into time series that preserve information on both the spatial extent and the temporal continuity of deposition. These macrostratigraphic quantities should, in principle, relate quantitatively to the underlying forcing mechanisms that govern sedimentation. Here, we use a numerical model of continental-margin sedimentation to test the extent to which time-varying forcing mechanisms, including subsidence, sediment supply, and sea level change, can be detected quantitatively by the application of macrostratigraphy. Spectral and information-theoretic analyses of time series of D, p, and q show that (1) all three quantities contain significant information on the sea level change, sediment supply variability, and subsidence patterns specified in the model input and (2) they convey the relative strengths of multiple forcing processes and how the relative importance of these processes varies with temporal resolution. We also find that the process information of p, q, and D is very robust to incomplete spatial sampling of the deposits. Our results suggest that D, which reflects variations in the area of sediment coverage and its temporal persistence, may afford the single best macrostratigraphic quantity for capturing the entire range of forcing mechanisms. Macrostratigraphy thus extends many of the well-known links between sequence architecture and sedimentary processes into a quantitative framework for statistical analyses of entire basin-fill successions. [ABSTRACT FROM AUTHOR]

Stratophenetic data document phenotypic changes in a fossil lineage and play a vital role in reconciling contemporary microevolution with long-term paleontological patterns. However, stratophenetic series represent multiscale geological and biological interactions, defying simple analysis and interpretation. A numerical model is presented that simulates stratophenetic series in shallow marine siliciclastic deposits. The model is driven by predictions of water depth, substrate properties, and sedimentation rate from a high-resolution sedimentary basin fill model. Species abundance is modeled as a probability density peaked with respect to environmental preferences. The Price equation is used to model phenotypic evolution based on phenotype-fitness covariance and drift. Preservation is a Poisson process controlled by population size, preservation probability, and sedimentation. Numerical experiments are used to investigate (1) the effects of sampling and depositional architecture on observed patterns and (2) the performance of various statistical tests in identifying evolutionary mode. As sample sizes decrease, the inaccuracy of sample mean values causes a stratophenetic pattern referred to as analytical stasis. Depositional architecture can cause nonrandom patterns through temporally irregular preservation, with the relative size and distribution of gaps being more important than the absolute size of gaps and overall completeness. For short series, statistical tests based on a random-walk null hypothesis lose power and should be abandoned in favor of a multidimensional approach. A model of the data is needed that can account for confounding factors, and all available information on time and environment as well as phenotypic data should be incorporated and analyzed jointly, with a greater emphasis on quantifying uncertainty. [ABSTRACT FROM AUTHOR]

More than half of the global ocean floor is draped by nutrient-starved sediments characterized by deep oxygen penetration and a prevalence of oxidized nitrogen. Despite low energy availability, this habitat hosts a vast microbial population, and geochemical characteristics suggest that nitrogen compounds are an energy source critical to sustaining this biomass. However, metabolic rates of nitrogen transformation and their link to microbial survival in this global-scale ecosystem remain virtually unknown. Here we provide quantitative constraints on microbial nitrogen cycling in open ocean oligotrophic sediments from seafloor to basement, spanning approximately 8 million years. We find active microbial nitrogen transformation throughout the sediment column but at very low rates. Local peaks in diversity and abundance of nitrifiers and denitrifiers occur at redox transition zones deep within the sediments, strongly indicating that these microbes are revived from their maintenance state and start growing again after millions of years of attrition. [ABSTRACT FROM AUTHOR]

The article discusses the study of correlation between the microbial communities with the geochemical data in the region of Arctic Mid-Ocean Ridge deposited at the sediments. It mentions the formation of complex communities by the microbes with the metabolic activity which affects the global biogeochemical cycles, and highlights the extraction and determination of 16S rRNA genes of approximately 60,000 microbes.

We present a source-to-sink analysis to explain sediment supply variations and depositional patterns over the Holocene within an active rift setting. We integrate a range of modelling approaches and data types with field observations from the Sperchios rift basin, Central Greece that allow us to analyse and quantify (1) the size and characteristics of sediment source areas, (2) the dynamics of the sediment routing system from upstream fluvial processes to downstream deposition at the coastline, and (3) the depositional architecture and volumes of the Holocene basin fill. We demonstrate that the Sperchios rift comprises a 'closed' system over the Holocene and that erosional and depositional volumes are thus balanced. Furthermore, we evaluate key controls in the development of this source-tosink system, including the role of pre-existing topography, bedrock erodibility and lateral variations in the rate of tectonic uplift/subsidence. We show that tectonic subsidence alone can explain the observed grain size fining along the rift axis resulting in the downstream transition from a braided channel to an extensive meander belt (>15 km long) that feeds the fine-grained Sperchios delta. Additionally, we quantify the ratios of sediment storage to bypass for the two main footwall-sourced alluvial fan systems and relate the fan characteristics to the pattern and rates of fault slip. Finally, we show that ≥40% of the sediment that builds the Sperchios delta is supplied by ≤22% of the entire source area and that this can be primarily attributed to a longer-term (∼106 years) transient landscape response to fault segment linkage. Our multidisciplinary approach allows us to quantify the relative importance of multiple factors that control a complex source-to-sink system and thus improve our understanding of landscape evolution and stratigraphic development in active extensional tectonic settings. [ABSTRACT FROM AUTHOR]

We propose a method for computing the transfer entropy between time series using Ulam's approximation of the Perron-Frobenius (transfer) operator associated with the map generating the dynamics. Our method differs from standard transfer entropy estimators in that the invariant measure is estimated not directly from the data points, but from the invariant distribution of the transfer operator approximated from the data points. For sparse time series and low embedding dimension, the transfer operator is approximated using a triangulation of the attractor, whereas for data-rich time series or higher embedding dimension, we use a faster grid approach. We compare the performance of our methods with existing estimators such as the k nearest neighbors method and kernel density estimation method, using coupled instances of well known chaotic systems: coupled logistic maps and a coupled Rössler-Lorenz system. We find that our estimators are robust against moderate levels of noise. For sparse time series with less than 100 observations and low embedding dimension, our triangulation estimator shows improved ability to detect coupling directionality, relative to standard transfer entropy estimators. [ABSTRACT FROM AUTHOR]

Cryoturbation, the burial of topsoil material into deeper soil horizons by repeated freeze-thaw events, is an important storage mechanism for soil organic matter (SOM) in permafrost-affected soils. Besides abiotic conditions, microbial community structure and the accessibility of SOM to the decomposer community are hypothesized to control SOM decomposition and thus have a crucial role in SOM accumulation in buried soils. We surveyed the microbial community structure in cryoturbated soils from nine soil profiles in the northeastern Siberian tundra using high-throughput sequencing and quantification of bacterial, archaeal and fungal marker genes. We found that bacterial abundances in buried topsoils were as high as in unburied topsoils. In contrast, fungal abundances decreased with depth and were significantly lower in buried than in unburied topsoils resulting in remarkably low fungal to bacterial ratios in buried topsoils. Fungal community profiling revealed an associated decrease in presumably ectomycorrhizal (ECM) fungi. The abiotic conditions (low to subzero temperatures, anoxia) and the reduced abundance of fungi likely provide a niche for bacterial, facultative anaerobic decomposers of SOM such as members of the Actinobacteria, which were found in significantly higher relative abundances in buried than in unburied topsoils. Our study expands the knowledge on the microbial community structure in soils of Northern latitude permafrost regions, and attributes the delayed decomposition of SOM in buried soils to specific microbial taxa, and particularly to a decrease in abundance and activity of ECM fungi, and to the extent to which bacterial decomposers are able to act as their functional substitutes. [ABSTRACT FROM AUTHOR]

Changes in Earth’s orbit set the pace of glacial cycles, but the role of spatial variability in the insolation forcing of global ice volume remains unknown. Here, we leverage the intrinsic dynamical information in empirical records to show that ice volume responded to summer energy at high northern latitudes, as predicted by Milankovitch theory. However, the external forcing of ice volume encompasses insolation signals with a wide range of orbital frequency content, and cannot be fully accounted for by a unique time series. Southern mid-latitude insolation forcing coincides with the position of the subtropical front and the westerlies, which have been implicated in Quaternary climate changes. Dominant forcing modes at northern mid-latitudes are anti-phased with the canonical Milankovitch forcing, consistent with ice volume sensitivity to latitudinal insolation gradients. [ABSTRACT FROM AUTHOR]