University of Konstanz
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Socio-structural determinants of physical activity behavior in children and adolescents : The importance of social support
No full textThe purpose of this study is to analyze the influence of socio-structural determinants of physical activity (PA) behavior in children and adolescents. We expected that socioeconomic status, social support, and physical environment influence PA directly while socioeconomic status also has an indirect influence via social support and physical environment. Cross-sectional data from the German Motorik-Modul study (MoMo) were used (Wave 2, 2014–2017). The sample consisted of N = 2134 children and adolescents aged 6–17 years. Socioeconomic status, social support, and physical environment were measured by questionnaires. To measure PA, children and adolescents were instructed to wear accelerometers for seven consecutive days. Moderate-to-vigorous activity periods were considered. Path analyses were used to analyze the direct and indirect effects. We calculated two models, one for children (6–10 years) and one for adolescents (11–17 years). Among children (model 1), only social support had a direct effect on PA behavior. In addition, social support influenced the perceived physical environment. Socioeconomic status had an indirect effect on PA via social support. For adolescents (model 2), all assumed relations were significant and in line with the directions expected. Social support had the strongest direct influence on PA behavior. Socioeconomic status had a direct and indirect effect on PA via the physical environment and social support. The study results emphasize the relevance of close, social networks of families and friends as well as social capital, as a source of social support, for PA levels among young age groups.publishe
Effects of extreme drought on the invasion dynamics of non-native plants
No full textThe increasing frequency of extreme droughts poses significant challenges for predicting the invasion success (or failure) of non-native plant species. While current frameworks are primarily based on moderate droughts, the unique characteristics of extreme droughts necessitate re-evaluating our understanding of plant invasion during and after extreme droughts. Here, using core principles of community assembly and invasion biology, we discuss how the invasibility of non-native plants during and after extreme droughts differs due to: (i) differences in the ecological response of the native community, (ii) barriers at different invasion stages, and (iii) the traits of non-native plants. We incorporate ideas from current ecological theories of invasive success and suggest how drought-mediated invasion is influenced by biotic interactions in the native community.publishe
Cross-Continental Shifts of Ecological Strategy in a Global Plant Invader
No full textAim
Plant invasions are a global problem that requires studying plants and their environmental associations across native and introduced ranges.
Location
2000 km transects in China, Europe and North America.
Time Period
June 2019–July 2020.
Major Taxa Studied
Japanese knotweed (Reynoutria japonica).
Methods
We surveyed 150 populations of Japanese knotweed, a noxious invader of the temperate zone, along 2000 km transects in native China and the introduced ranges of Europe and North America.
Results
We found that larger plants and denser populations in the introduced ranges were associated with shifts in leaf economy and chemical defences. Introduced knotweed populations had higher SLA but reduced leaf chlorophyll, lignin, C:N ratio and leaf toughness along with altered leaf tannins, flavonoids and alkaloids. We found three distinct multivariate knotweed phenotypes primarily in the introduced ranges, and two multivariate knotweed phenotypes mainly in native populations.
Main Conclusions
Decreased herbivore and pathogen impacts in introduced populations and changes in environmental associations indicate that enemy release and novel habitat conditions might have driven the emergence of novel ecological strategies in this global plant invader.publishe
Do Egg Hormones Have Fitness Consequences in Wild Birds? : A Systematic Review and Meta‐Analysis
No full textEgg‐laying species are key models for understanding the adaptive significance of maternal effects, with egg hormones proposed as an important underlying mechanism. However, even thirty years after their discovery, the evolutionary consequences of hormone‐mediated maternal effects remain unclear. Using evidence synthesis, we tested the extent to which increased prenatal maternal hormone deposition in eggs relates to fitness in wild birds (19 species, 438 effect sizes and 57 studies). Egg androgens, glucocorticoids, and thyroid hormones showed an overall near‐zero mean effect for both maternal and offspring fitness proxies. However, heterogeneity was high, suggesting that egg hormone effects on fitness are context‐dependent. Hormone type and age did not explain much of the observed variance, nor did methodological factors such as the type of study or experimental design. Heterogeneity decomposition showed that differences in effect sizes were mostly driven by within‐study variability and phylogenetic relationships. Our study provides the most comprehensive investigation to date of the relationship between egg hormones and fitness in vertebrates. By synthesising current knowledge, we aim to overcome theoretical shortcomings in the field of maternal effects via egg hormone deposition and inspire new research into its many intriguing aspects.publishe
The role of native language and beat perception ability in the perception of speech rhythm
No full textThe perception of rhythm has been studied across a range of auditory signals, with speech presenting one of the particularly challenging cases to capture and explain. Here, we asked if rhythm perception in speech is guided by perceptual biases arising from native language structures, if it is shaped by the cognitive ability to perceive a regular beat, or a combination of both. Listeners of two prosodically distinct languages - English and French - heard sentences (spoken in their native and the foreign language, respectively) and compared the rhythm of each sentence to its drummed version (presented at inter-syllabic, inter-vocalic, or isochronous intervals). While English listeners tended to map sentence rhythm onto inter-vocalic and inter-syllabic intervals in this task, French listeners showed a perceptual preference for inter-vocalic intervals only. The native language tendency was equally apparent in the listeners’ foreign language and was enhanced by individual beat perception ability. These findings suggest that rhythm perception in speech is shaped primarily by listeners’ native language experience with a lesser influence of innate cognitive traits.publishe
Venue‐Making
No full textVenue‐making describes the process of turning political issues into political institutions. Both public policy and institutionalist scholars have addressed the puzzle of when and how new political institutions arise. We draw on both perspectives, arguing that the interaction between interest groups and government ultimately determines whether an issue remains within the existing institutional setting or if a new venue is made. A repeated stag hunt game illuminates the challenges of this interaction: interest groups and government need to coordinate the move from an old to a new venue by amplifying the issue and creating new institutional structures simultaneously. Because the switch from subsystem politics to venue‐making is rewarding but also risky, several mechanisms, including signaling, sustained interaction, and inspection, encourage cooperation. Our research design provides an analysis of three case studies in a fixed institutional context of unified Germany. A first case process‐traces how political issues about digitalization emerged and became institutionalized. A second, off‐path case shows the short‐lived attempt to centralize administrative competences in the domain of energy policy underscores the crucial role of interest groups. The third case explains the ultimately futile attempt to create a new Ministry of Immigration.publishe
Aliphatic–Aromatic Copolyesters with Waste-Sourceable Multiple Chain-Length Building Blocks
No full textSourcing commodity polymers from sustainable alternative feedstocks, such as those derived from plastic waste or biobased resources, is a promising approach to alleviate the reliance on finite fossil fuel stocks for the production of virgin plastics. Linear aliphatic dicarboxylic acids of multiple chain lengths can be obtained from polyethylene (PE) waste, and their use in the synthesis of aliphatic polyesters has recently been demonstrated. To improve the materials’ properties of polyesters derived from multiple chain-length dicarboxylates, we herein combined this feedstock with terephthalate as an aromatic monomer unit to yield aliphatic-aromatic copolyesters. We established structure-property relationships for copolyesters derived from aliphatic dicarboxylates of multiple chain lengths (C4-C20) as a model for catalytic oxidation products of PE waste, or from 1,18-ctadecanedioate as reference materials for polyesters from single, long chain length dicarboxylates. Thermal properties and solid-state structures were dominated by the ratio of aliphatic to aromatic monomer units rather than the identity of the aliphatic dicarboxylate or diol components. We demonstrated upscaling of the copolyester synthesis, as well as processability and mechanical properties of a multiple chain length copolyester, which showed comparable properties to the commercial polybutylene adipate-co-terephthalate. Finally, we showed an alternative production via catalytic transesterification and thus postmodification of premade polyesters, including postconsumer polyethylene terephthalate, as model waste sources.publishe
Rapid Evolution in Action: Environmental Filtering Supports Coral Adaptation to a Hot, Acidic, and Deoxygenated Extreme Habitat
No full textThe semienclosed Bouraké lagoon in New Caledonia is a natural system that enables observation of evolution in action with respect to stress tolerance in marine organisms, a topic directly relevant to understanding the consequences of global climate change. Corals inhabiting the Bouraké lagoon endure extreme conditions of elevated temperature (> 33°C), acidification (7.2 pH units), and deoxygenation (2.28 mg O2 L-1), which fluctuate with the tide due to the lagoon's geomorphology. To investigate the underlying bases of the apparent stress tolerance of these corals, we combined whole genome resequencing of the coral host and ITS2 metabarcoding of the photosymbionts from 90 Acropora tenuis colonies from three localities along the steep environmental gradient from Bouraké to two nearby control reefs. Our results highlight the importance of coral flexibility to associate with different photosymbionts in facilitating stress tolerance of the holobiont; but, perhaps more significantly, strong selective effects were detected at specific loci in the host genome. Fifty-seven genes contained SNPs highly associated with the extreme environment of Bouraké and were enriched in functions related to sphingolipid metabolism. Within these genes, the conserved sensor of noxious stimuli TRPA1 and the ABCC4 transporter stood out due to the high number of environmentally selected SNPs that they contained. Protein 3D structure predictions suggest that a single-point mutation causes the rotation of the main regulatory domain of TRPA1, which may be behind this case of natural selection through environmental filtering. While the corals of the Bouraké lagoon provide a striking example of rapid adaptation to extreme conditions, overall, our results highlight the need to preserve the current standing genetic variation of coral populations to safeguard their adaptive potential to ongoing rapid environmental change.publishe
Thermo-Mechanical Degradation Kinetics of a High-Density Poly(Ethylene) Using a Closed-Cavity Rheometer
No full textMechanical recycling of polymers is an essential aspect to achieve circular economy. High shear stress, excessive temperature, and long residence time during reprocessing cause thermo-mechanical degradation of the polymer. Therefore, it is important to understand and quantify this degradation kinetics. Common ways to simulate degradation are very time and material consuming and clear insights into the respective influence of temperature and shear stress on degradation are rare. Within this publication a method is developed using a commercially available, close-cavity rheometer to emulate processing conditions in a defined way. This allows monitoring and predicting the behavior of a high-density polyethylene (HDPE) and quantify degradation kinetics and changes in the polymer topology. HDPE is selected as a model polymer due to its large production and wide range of applications. Different treated samples are analyzed by various rheological methods. Additionally, molecular characterization is conducted. A kinetic model to predict the changes in the molecular weight as a function of in-phase shear stress, temperature and duration during treatment is presented. The calculated activation energy for the initiation reaction agrees with the activation energy for HDPE degradation from thermogravimetric analysis. This activation energy is lowered by in-phase shear stress, modified by a factor of 1.7 m3 mol−1.publishe