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Keystone predation is the process whereby a predator indirectly facilitates weak competitors by preferentially consuming strong competitors, often affecting local diversity. The keystone predation process is therefore different from keystone species, which refers to any species with a large and disproportionately large effect relative to its abundance. Keystone predation is widely cited as a fundamental ecological process in textbooks and scientific literature, but its empirical evidence has not been reviewed. We addressed this research gap by reviewing papers that explicitly (a) tested for keystone predation with experiments or models, and/or (b) mentioned ‘keystone predation’ in their main text, to assess its prevalence and identify potential context dependencies. We found that almost 2000 publications mentioned keystone predation in their texts, but only 73 papers tested or discussed the process in detail. Most of the 73 studies were from North America (87.4%), temperate (59.4%) and aquatic habitats (48% freshwater, 44% marine). Just 25 publications manipulated predator abundances to explicitly test for keystone predation, of which 10, 7 and 8 publications reported consistent support (mobile invertebrates preying on sessile competitors), context‐dependent support (effects varied, e.g., with temperature or nutrients) or no support (mobile competitors), respectively. The few studies that tested keystone predation make it difficult to evaluate its prevalence, its relative importance, or whether general rules exist to predict its strength. Still, the few published studies suggest that environment, species traits and dispersal can modify keystone predation. We also recognise that more papers may have tested for keystone predation, but lacked this terminology. These papers should be identified in future meta‐analyses by combining wider search terms and expert knowledge. We recommend that researchers use the precise keystone predation terminology to experimentally test this process on different consumer–prey communities and under contrasting environmental conditions, to better understand its prevalence and importance in ecology. Keystone predation has been widely cited as a key ecological mechanism controlling community structures, but is supported by limited theoretical and experimental studies. Reviewing these studies showed keystone predation has been documented across realms, appears to be most prevalent in sessile and dispersal‐limited communities and can be modified by environmental conditions, species traits and dispersal. Therefore, more research that explicitly tests for keystone predation on different predator–prey communities and under contrasting environmental conditions is needed to better understand its prevalence and importance in ecology.

Species’ foraging choices influence their somatic growth rates, age at maturity, and time spent in vulnerable early life stages. Thus, differences in population demographics are often attributed to variability either in diet type, quality, and/or quantity ingested. Knowledge of diet selection, though currently limited, can enhance our understanding of the roles of marine turtles in marine ecosystems and, at a finer scale, elucidate how nutrition and diet influence their growth and productivity. To investigate this relationship, we coupled stable isotope analysis with a diet preference index to provide insights into the selection and plasticity of juvenile green turtle Chelonia mydas diet. The study was conducted at 2 sites (Bonefish Hole and South Bimini) in Bimini, Bahamas, in 2016. Habitat surveys were conducted to gather habitat data and determine resource availability. A dichotomy in diet was found between the sites: at Bonefish Hole, turtles exhibited a more generalist omnivorous diet, selecting for sessile filter feeders and green algae, whereas turtles in South Bimini had a more specialist herbivorous diet, primarily consuming seagrasses and selecting for red algae, when available. The foraging dichotomy found in this study expands our understanding of the spatial differences in green turtle biology in the Bahamas and provides novel information for turtle foraging in Bimini. Knowledge about differences in intra-specific diet, with a focus on diet selection and potential drivers, can shed light on the factors that influence critical life history traits and ultimately inform species management.

Diet selection by a species is determined by comparing the consumption (i.e., use) and abundance (i.e., availability) of prey within their area of occupancy. Because individuals commonly use only a portion of habitat available to them (e.g., a 10-ha home range within a 1000-ha foraging habitat), it is important to quantify forage availability within individuals’ home ranges and core areas, and include these availabilities when calculating diet selection. However, studies of diet selection often consider prey availability across the entire foraging habitat of a species and not within individual home ranges/core areas. Here, we explore how spatial variability in prey availability may influence the results of diet selection for juvenile green turtles, Chelonia mydas, foraging in Bimini, Bahamas. Stable isotope analysis was used to determine prey use and satellite telemetry to infer movements and forage availability for each turtle. Forage availability was assessed at three spatial scales: (1) the full extent of the foraging area (2) across each respective individual’s 95% utilization distribution (UD), or home ranges, and (3) across each individual’s 50% UD, or core areas. Further, we compared potential differences in diet selection by using three selection indices (Ivlev’s, Johnson’s and Chesson’s). Diet selection results varied among individuals and were influenced by the spatial scale of forage items available and the index used. Diet selection variability was observed at various spatial scales and in all indices. Our results highlight the need for careful consideration of the diet selection index and the spatial scale at which prey/forage availability is considered when determining a species’ diet selection. Selecting a more sensitive index will help identify priority resources and/or habitats that are important to species, which in turn carries conservation and management implications.

Knowledge on the spatial distribution, habitat use and processes of site selection by marine turtles is fundamental to identify key habitats, critical resources, and discrete foraging aggregations for protection. This is particularly important for regions of known importance for marine turtles and where widespread habitat degradation is taking place. The waters surrounding Bimini, Bahamas, provide important foraging areas for threatened juvenile green turtles (Chelonia mydas) however, these habitats are being severely degraded by coastal development. To inform managers on the design of planned future no-take marine protected areas (MPA) in Bimini, we used a spatial planning approach and incorporated diverse methodologies (e.g., visual surveys, capture events, passive acoustic telemetry) to identify areas of high use by juvenile green turtles. We also assessed forage items to understand habitat use by green turtles. This information was compared with how various stakeholders use the local waters to identify priority areas for protection within Bimini to maximize conservation of green turtles, while minimizing impact to society, and to meet the conservation target previously stipulated by government officials. Two regions within Bimini (South Flats in south Bimini and Bonefish Hole on the north Island) were identified as important areas for protection and suggestions are made on their considerations for MPA implementation.

Sea turtles migrate thousands of miles annually between foraging and breeding areas, carrying dozens of epibiont species with them on their journeys. Most sea turtle epibiont studies have focused on large-sized organisms, those visible to the naked eye. Here, we report previously undocumented levels of epibiont abundance and biodiversity for loggerhead sea turtles (Caretta caretta), by focusing on the microscopic meiofauna. During the peak of the 2018 loggerhead nesting season at St. George Island, Florida, USA, we sampled all epibionts from 24 carapaces. From the subsamples, we identified 38,874 meiofauna individuals belonging to 20 higher taxa. This means 810,753 individuals were recovered in our survey, with an average of 33,781 individuals per carapace. Of 6992 identified nematodes, 111 different genera were observed. To our knowledge, such levels of sea turtle epibiont abundance and diversity have never been recorded. Loggerhead carapaces are without doubt hotspots of meiofaunal and nematode diversity, especially compared to other non-sedimentary substrates. The posterior carapace sections harbored higher diversity and evenness compared to the anterior and middle sections, suggesting increased colonization and potentially facilitation favoring posterior carapace epibiosis, or increased disturbance on the anterior and middle carapace sections. Our findings also shed new light on the meiofauna paradox: “How do small, benthic meiofauna organisms become cosmopolitan over large geographic ranges?” Considering high loggerhead epibiont colonization, the large distances loggerheads migrate for reproduction and feeding, and the evolutionary age and sheer numbers of sea turtles worldwide, potentially large-scale exchange and dispersal for meiofauna through phoresis is implied. We distinguished different groups of loggerhead carapaces based on divergent epibiont communities, suggesting distinct epibiont colonization processes. These epibiont observations hold potential for investigating loggerhead movements and, hence, their conservation.

Species’ foraging choices influences their somatic growth rates, age at maturity, and time spent in vulnerable early life stages. Thus, differences in population demographics are often attributed to variability either in diet type, quality or quantity ingested. Knowledge of species diet selection, though currently limited, particularly in marine environments, can enhance our understanding of the roles of species in marine ecosystem and, at a finer scale, elucidate how nutrition and diet influences their growth and productivity. Marine green turtles (Chelonia mydas) are considered to be herbivores, predominantly consuming seagrass and algae. However, recent studies have suggested that they may exhibit omnivory in certain forage areas. Using juvenile green turtles as a case study, I coupled stable isotope analysis with a diet preference index to provide insights into the selection and plasticity of their diet. The study was conducted within two sites (Bonefish Hole and South Bimini) in Bimini, Bahamas in 2016. Habitat surveys were conducted to gather habitat data and determine resource availability. A dichotomy in diet was found between the sites: at Bonefish Hole, turtles exhibited a more generalist omnivorous diet, selecting for sessile filters feeders and green algae, whereas turtles in South Bimini had a more specialist herbivorous diet, primarily consuming seagrasses and selecting for red algae, when available. The foraging dichotomy found in this study by green turtles expands our understanding of the spatial differences in their biology in the Bahamas and provides novel information for turtle foraging in Bimini. Knowledge about differences in intra-specific diet, with a focus on diet selection and potential drivers, can elucidate the factors that influence critical life history traits and ultimately inform species management.

Compositional uniqueness has become increasingly relevant for understanding how local communities contribute to regional biodiversity. The most widely used metric is the Local Contribution to Beta Diversity (LCBD), which is typically regressed against environmental predictors. However, LCBD can vary either because of environmental processes that affect the overall variance in community composition, or because communities change directionally along environmental gradients. The latter implies that LCBD–environment relationships can strongly depend on how the environment is sampled. To address this issue, we introduce Generalised Dissimilarity Uniqueness Models (GDUM), a framework that embeds effects on community uniqueness within pairwise dissimilarity modelling. GDUMs are consistent with conventional uniqueness models, while explicitly accounting for directional changes in composition. This distinction disentangles directional and non-directional drivers of beta diversity, such as environmental filtering versus stochastic processes. By improving interpretability and generalizability, GDUM is a useful tool for understanding beta diversity patterns and projecting biodiversity responses.

A common hallmark of human cancers is the overexpression of telomerase, a ribonucleoprotein complex that is responsible for maintaining the length and integrity of chromosome ends. Telomere length deregulation and telomerase activation is an early, and perhaps necessary, step in cancer cell evolution. Here we present the high-resolution structure of the Tribolium castaneum catalytic subunit of telomerase, TERT. The protein consists of three highly conserved domains, organized into a ring-like structure that shares common features with retroviral reverse transcriptases, viral RNA polymerases and B-family DNA polymerases. Domain organization places motifs implicated in substrate binding and catalysis in the interior of the ring, which can accommodate seven to eight bases of double-stranded nucleic acid. Modelling of an RNA-DNA heteroduplex in the interior of this ring demonstrates a perfect fit between the protein and the nucleic acid substrate, and positions the 3'-end of the DNA primer at the active site of the enzyme, providing evidence for the formation of an active telomerase elongation complex.

Glycopeptide antibiotics are regularly used in ophthalmology to treat infections of Gram-positive bacteria. Aggregative interactions of antibiotics with mucins however can lead to long exposure and increases the risk of resistant species. This study focuses on the evaluation of potential interactions of the last line of defence glycopeptide antibiotic teicoplanin with an ocular mucin model using precision matrix free hydrodynamic and microscopic techniques: sedimentation velocity in the analytical ultracentrifuge (SV-AUC), dynamic light scattering (DLS) and atomic force microscopy (AFM). For the mixtures of teicoplanin at higher doses (1.25 mg/mL and 12.5 mg/mL), it was shown to interact and aggregate with bovine submaxillary mucin (BSM) in the distributions of both sedimentation coefficients by SV-AUC and hydrodynamic radii by DLS. The presence of aggregates was confirmed by AFM for higher concentrations. We suggest that teicoplanin eye drop formulations should be delivered at concentrations of < 1.25 mg/mL to avoid potentially harmful aggregations.

Several recent reviews have suggested that cognitive rehabilitation may hold promise in the treatment of memory deficits experienced by patients with mild cognitive impairment. In contrast to the previous reviews that mainly focused on outcome, the current review examines key methodological challenges that are critical for designing and interpreting research studies and translating results into clinical practice. Using methodological details from 36 studies, we first examine diagnostic variability and how the use of cutoffs may bias samples toward more severely impaired patients. Second, the strengths and limitations of several common rehabilitative techniques are discussed. Half of the reviewed studies used a multi-technique approach that precludes the causal attribution between any specific technique and subsequent improvement. Third, there is a clear need to examine the dose-response relationship since this information was strikingly absent from most studies. Fourth, outcome measures varied widely and frequently depended on neuropsychological tests with little theoretical justification or ecological relevance. Fifth, we discuss how the variability in each of these other four areas complicates efforts to examine training generalization. Overall, future studies should place greater emphasis on ecologically relevant treatment approaches and outcome measures and we propose a hierarchical model that may aid in this pursuit. (JINS, 2014, 19, 1–17)