Divergence of feeding channels within the soil food web determined by ecosystem type.

Understanding trophic linkages within the soil food web (SFW) is hampered by its opacity, diversity, and limited niche adaptation. We need to expand our insight between the feeding guilds of fauna and not just count biodiversity. The soil fauna drive nutrient cycling and play a pivotal, but little understood role within both the carbon (C) and nitrogen (N) cycles that may be ecosystem dependent. Here, we define the structure of the SFW in two habitats (grassland and woodland) on the same soil type and test the hypothesis that land management would alter the SFW in these habitats. To do this, we census the community structure and use stable isotope analysis to establish the pathway of C and N through each trophic level within the ecosystems. Stable isotope ratios of C and N from all invertebrates were used as a proxy for trophic niche, and community-wide metrics were obtained. Our empirically derived C/N ratios differed from those previously reported, diverging from model predictions of global C and N cycling, which was unexpected. An assessment of the relative response of the different functional groups to the change from agricultural grassland to woodland was performed. This showed that abundance of herbivores, microbivores, and micropredators were stimulated, while omnivores and macropredators were inhibited in the grassland. Differences between stable isotope ratios and community-wide metrics, highlighted habitats with similar taxa had different SFWs, using different basal resources, either driven by root or litter derived resources. Overall, we conclude that plant type can act as a top-down driver of community functioning and that differing land management can impact on the whole SFW

Стратегии и тактики речевого воздействия в русском и французском Интернет-дискурсе (на материале корпоративных веб-сайтов)

Данная работа посвящена исследованию речевого воздействия в текстах деловой коммуникации корпоративных веб-сайтов Интернет - дискурса. Целью данного исследования является выявление стратегий и тактик речевого воздействия в русском и французском Интернет-дискурсе.This thesis work is devoted to the study of speech influence in the texts of business communication of corporate websites of Internet-discourse. The purpose of this study is to identify strategies and tactics of speech influence in Russian and French Internet-discourse

How Many Species Are There on Earth and in the Ocean?

The diversity of life is one of the most striking aspects of our planet; hence knowing how many species inhabit Earth is among the most fundamental questions in science. Yet the answer to this question remains enigmatic, as efforts to sample the world's biodiversity to date have been limited and thus have precluded direct quantification of global species richness, and because indirect estimates rely on assumptions that have proven highly controversial. Here we show that the higher taxonomic classification of species (i.e., the assignment of species to phylum, class, order, family, and genus) follows a consistent and predictable pattern from which the total number of species in a taxonomic group can be estimated. This approach was validated against well-known taxa, and when applied to all domains of life, it predicts ∼8.7 million (±1.3 million SE) eukaryotic species globally, of which ∼2.2 million (±0.18 million SE) are marine. In spite of 250 years of taxonomic classification and over 1.2 million species already catalogued in a central database, our results suggest that some 86% of existing species on Earth and 91% of species in the ocean still await description. Renewed interest in further exploration and taxonomy is required if this significant gap in our knowledge of life on Earth is to be closed

Local stability properties of complex, species-rich soil food webs with functional block structure

Publication history: Accepted - 14 October 2021; Published online - 3 November 2021.Ecologists have long debated the properties that confer stability to complex, species-rich ecological networks. Species-level soil food webs are large and structured networks of central importance to ecosystem functioning. Here, we conducted an analysis of the stability properties of an up-to-date set of theoretical soil food web models that account both for realistic levels of species richness and the most recent views on the topological structure (who is connected to whom) of these food webs. The stability of the network was best explained by two factors: strong correlations between interaction strengths and the blocked, nonrandom trophic structure of the web. These two factors could stabilize our model food webs even at the high levels of species richness that are typically found in soil, and that would make random systems very unstable. Also, the stability of our soil food webs is well-approximated by the cascade model. This result suggests that stability could emerge from the hierarchical structure of the functional organization of the web. Our study shows that under the assumption of equilibrium and small perturbations, theoretical soil food webs possess a topological structure that allows them to be complex yet more locally stable than their random counterpart. In particular, results strongly support the general hypothesis that the stability of rich and complex soil food webs is mostly driven by correlations in interaction strength and the organization of the soil food web into functional groups. The implication is that in real-world food web, any force disrupting the functional structure and distribution pattern of interaction strengths (i.e., energy fluxes) of the soil food webs will destabilize the dynamics of the system, leading to species extinction and major changes in the relative abundances of species.TC was supported by the project SENSE (Structure and Ecological Niche in the Soil Environment; EC FP7 –631399 –SENSE). TC and FdC were also supported by the NERC Grant Controls on the stability of soils and their functioning under land use and climate change (NE/M017036/1) as was RDB (NE/M017028/1). MÖ was supported by the European Regional Development Fund [Centre of Excellence EcolChange]

Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes

This revision of the classification of eukaryotes follows that of Adl et al., 2012 [J. Euk. Microbiol. 59(5)] and retains an emphasis on protists. Changes since have improved the resolution of many nodes in phylogenetic analyses. For some clades even families are being clearly resolved. As we had predicted, environmental sampling in the intervening years has massively increased the genetic information at hand. Consequently, we have discovered novel clades, exciting new genera, and uncovered a massive species level diversity beyond the morphological species descriptions. Several clades known from environmental samples only have found their home. Sampling soils, deeper marine waters, and the deep sea will continue to fill us with surprises. The main changes in this revision are the confirmation that eukaryotes form at least two domains, the loss of monophyly in the Exavata, robust support for the Haptista and Cryptista. We provide suggested primer sets for DNA sequences from environmental samples that are effective for each clade. We have provided a guide to trophic functional guilds in an appendix, to facilitate the interpretation of environmental samples. This revision of the classification of eukaryotes updates that of the International Society of Protistologists (Adl et al., 2012). Since then, there has been a massive increase in DNA sequence information of phylogenetic relevance from environmental samples. We now have a much better sense of the undescribed biodiversity in our environment (Pawlowski et al., 2012; de Vargas et al., 2015). While significant, it still remains a partial estimation as several continents and soils in general are poorly sampled, and the deeper ocean is hard to reach. This new data clarified phylogenetic relationships and the new information is incorporated in this revision

Soil protistology rebooted: 30 fundamental questions to start with

Protists are the most diverse eukaryotes. These microbes are keystone organisms of soil ecosystems and regulate essential processes of soil fertility such as nutrient cycling and plant growth. Despite this, protists have received little scientific attention, especially compared to bacteria, fungi and nematodes in soil studies. Recent methodological advances, particularly in molecular biology techniques, have made the study of soil protists more accessible, and have created a resurgence of interest in soil protistology. This ongoing revolution now enables comprehensive investigations of the structure and functioning of soil protist communities, paving the way to a new era in soil biology. Instead of providing an exhaustive review, we provide a synthesis of research gaps that should be prioritized in future studies of soil protistology to guide this rapidly developing research area. Based on a synthesis of expert opinion we propose 30 key questions covering a broad range of topics including evolution, phylogenetics, functional ecology, macroecology, paleoecology, and methodologies. These questions highlight a diversity of topics that will establish soil protistology as a hub discipline connecting different fundamental and applied fields such as ecology, biogeography, evolution, plant-microbe interactions, agronomy, and conservation biology. We are convinced that soil protistology has the potential to be one of the most exciting frontiers in biology

Regulation of cell cycle duration, cell size and life history in the ciliate sterkiella histriomuscorum

As eukaryotic cells grow and divide, their size remains within a limited range despite changes in resources available. Understanding cell cycle regulation can help understand how size constancy is achieved and provide the molecular and physiological clues to size regulation. However, it is not always obvious how to reconcile the physiological behaviour of cells with this molecular information. We chose the ciliate Sterkiella histriomuscorum (Oxytrichidae) to obtain new insights into size regulation. This organism re-adjusts its cell dimensions as resources diminish. It exits the cell cycle for conjugation or encystment when resources are scarce. A general model is proposed for ciliate cell cycle regulation and the cell cycle of Sterkiella was described within this context. Conditions for inducing conjugation, encystment and excystment were determined to obtain synchronous cultures, and to describe the timing of each process. Observations on the effect of clonal ageing on each process is described. These allow one to manipulate the organism predictably in the laboratory. The consequences of changes in food particle size, prey species, prey abundance and temperature on the size and cell cycle duration of Sterkiella were explained using Michaelis- Menten kinetics. Two parameters (Pmin and Pdiv) were then described and calculated, that were useful in predicting tendencies of cultures with one or two prey species. Two approaches were taken to understand this regulation of cell size physiologically. First, an attempt was made to find out if cAMP is an important regulator of cell cycle progression and duration of growth. Some ciliate "fat" mutants were rescued by drug treatments with inhibitors of kinases. Second, the c d mutant was rescued by transformation with a partial DNA library from wild type Paramecium. However, the rescuing element was not the c d gene. Finally, cell size regulation in several protists is provided with a unified jargon, from a physiological and molecular perspective. This allowed for the first time, a comparison of regulatory processes between species and the development of several ideas regarding cell size regulation. Several principles are proposed as generalities for testing.Science, Faculty ofZoology, Department ofGraduat