Differences in time until dispersal between cryptic species of a marine nematode species complex

Co-occurrence of closely related species may be achieved in environments with fluctuating dynamics, where competitively inferior species can avoid competition through dispersal. Here we present an experiment in which we compared active dispersal abilities (time until first dispersal, number and gender of dispersive adults, and nematode densities at time of dispersal) in Litoditis marina, a common bacterivorous nematode species complex comprising four often co-occurring cryptic species, Pm I, II, III, and IV, as a function of salinity and food distribution. The experiment was conducted in microcosms consisting of an inoculation plate, connection tube, and dispersal plate. Results show species-specific dispersal abilities with Pm I dispersing almost one week later than Pm III. The number of dispersive adults at time of first dispersal was species-specific, with one dispersive female in Pm I and Pm III and a higher, gender-balanced, number in Pm II and Pm IV. Food distribution affected dispersal: in absence of food in the inoculation plate, all species dispersed after ca four days. When food was available Pm I dispersed later, and at the same time and densities irrespective of food conditions in the dispersal plate (food vs no food), suggesting density-dependent dispersal. Pm III dispersed faster and at a lower population density. Salinity affected dispersal, with slower dispersal at higher salinity. These results suggest that active dispersal in Litoditis marina is common, density-dependent, and with species, gender- and environment-specific dispersal abilities. These differences can lead to differential responses under suboptimal conditions and may help to explain temporary coexistence at local scales

To stay or go: differential dispersal rates in cryptic species of a marine nematode

Behind the morphological similarity of many species, a hidden genetic diversity can be found. This cryptic diversity has been well documented in the marine nematode Rhabditis (Pellioditis) marina, a common bactivore associated with decomposing macro-algae in the littoral zone of coastal and estuarine environments. Four cryptic species of R. marina (Pm I, Pm II, Pm III and Pm IV) co-occur along the south-western coast and estuaries of The Netherlands. This coexistence challenges traditional competition theory, which states that competition will be most severe between closely related species. A previous study showed that competition between the four cryptic species occurred, but interspecific interactions were affected by environmental conditions such as salinity. One of the most important mechanisms to react to competition is dispersal. Most organisms have at least one stage in which dispersal occurs over a specific spatial scale. Meiobenthic species, however, lack any pelagic stage. But, recent research shows more and more evidence that meiofauna is also able to actively disperse with lateral sinusoidal movements in the interstitial spaces as one of the most common modes of dispersal of nematodes over short distances. Dispersal is a process triggered partially by the internal conditions of organisms and partially by environmental conditions. In the current experiment, species-specific differences in active dispersal rates and the effects of salinity and food distribution on dispersal behaviour were tested in four cryptic species of R. marina (Pm I, Pm II, Pm III and Pm IV), The results of the experiment showed that dispersal is a species-specific behaviour with Pm III being the most rapid disperser (first dispersal event occurred after an average of 3 days), and Pm I the slowest disperser (average of 10 days). An effect of food distribution on the dispersal rates of all cryptic species was found with the most rapid dispersal if no food was present at the start situation. Salinity also had an effect with a higher dispersal rate at lower salinity for all the species. Moreover, the number of dispersive organisms differed between the species, with only one female disperser in Pm I and Pm III and a mix of female and male dispersers for Pm II and Pm IV at the first dispersal event. This species-specific dispersal behaviour and the influence of external conditions on dispersal can influence the reaction on competition. In a future experiment the effect of competition on dispersal will be studied by using competition cultures, where all four cryptic species can influence each other, but the organisms have the chance to disperse away. These results are important to better understand the processes behind the coexistence of cryptic species

A vocabulary-independent generation framework for DBpedia and beyond

The dbpedia Extraction Framework, the generation framework behind one of the Linked Open Data cloud’s central hubs, has limitations which lead to quality issues with the dbpedia dataset. Therefore, we provide a new take on its Extraction Framework that allows for a sustainable and general-purpose Linked Data generation framework by adapting a semantic-driven approach. The proposed approach decouples, in a declarative manner, the extraction, transformation, and mapping rules execution. This way, among others, interchanging different schema annotations is supported, instead of being coupled to a certain ontology as it is now, because the dbpedia Extraction Framework allows only generating a certain dataset with a single semantic representation. In this paper, we shed more light to the added value that this aspect brings. We provide an extracted dbpedia dataset using a different vocabulary, and give users the opportunity to generate a new dbpedia dataset using a custom combination of vocabularies

The relationship between motor competence and health-related fitness in children and adolescents

Background and aims In the last twenty years, there has been increasing evidence that Motor Competence (MC) is vital for developing an active and healthy lifestyle. This study analyses the associations between motor competence and its components, with health-related fitness (HRF). Methods A random sample of 546 children (278 males, mean = 10.77 years) divided into four age groups (7?8; 9?10; 11?12; 13?14 years old) was evaluated. A quantitative MC instrument (evaluating stability, locomotor and manipulative skills), a maximal multistage 20-m shuttle-run test and the handgrip test, height and BMI were used in the analyses. Pearson correlations and standard regression modelling were performed to explore the associations between variables. Results Moderate to strong significant correlations (0.49 < r < 0.73) were found between MC and HRF, for both sexes, and correlation values were stable across the age groups. The MC model explained 74% of the HRF variance, with the locomotor component being the highest predictor for the entire sample (? = .302; p < .001). Gender-related differences were found when boys and girls were analysed at each age group. Locomotor MC for girls was the most consistent significant predictor of HRF across all age groups (0.47 < ? < 0.65; all p .001). For boys, significant predictors were locomotor and manipulative MC (0.21 < ? < 0.49; all p < .05) in the two younger age groups (7?8 and 9?10 years) and stability (0.50 < ? < 0.54; all p .001) for the older two age groups (11?12 and 13?14 years). Conclusion These results support the idea that: (1) the relationship between overall MC and HRF is strong and stable across childhood and early adolescence; (2) when accounting for the different MC components, boys and girls show different relationship patterns with HFR across age.4811-99FE-2ECD | Luis Paulo Rodriguesinfo:eu-repo/semantics/publishedVersio

Black Dialect in Children\u27s Books

Black non-Standard English is different in grammar (syntax) from Standard English. The advent of the 60\u27s produced authors who explored the full possibilities of language to deal with their themes. The increased use of dialect by black authors, particularly children\u27s authors, was a sign that the nature of the black experience as they wanted to convey it did not have to rely on traditional forms, and literary devices; that they could treat familiar, realistic ideas and situations using a familiar dialect and relate that idea more effectively