Machine learning ecological networks

Deep-learning tools can help to construct historical, modern-day, and future food webs</jats:p

Phenotypic Responses to a Lifestyle Intervention Do Not Account for Inter-Individual Variability in Glucose Tolerance for Individuals at High Risk of Type 2 Diabetes

Background: Lifestyle interventions have been shown to delay or prevent the onset of type 2 diabetes among high risk adults. A better understanding of the variability in physiological responses would support the matching of individuals with the best type of intervention in future prevention programmes, in order to optimize risk reduction. The purpose of this study was to determine if phenotypic characteristics at baseline or following a 12 weeks lifestyle intervention could explain the inter-individual variability in change in glucose tolerance in individuals with high risk for type 2 diabetes.Methods: In total, 285 subjects with normal glucose tolerance (NGT, FINDRISC score &gt; 12), impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) were recruited for a 12 weeks lifestyle intervention. Glucose tolerance, insulin sensitivity, anthropometric characteristics and aerobic fitness were measured. Variability of responses was examined by grouping participants by baseline glycemic status, by cluster analysis based on the change in glucose tolerance and by Principal Component Analysis (PCA).Results: In agreement with other studies, the mean response to the 12 weeks intervention was positive for the majority of parameters. Overall, 89% improved BMI, 80% waist circumference, and 81% body fat while only 64% improved fasting plasma glucose and 60% 2 h glucose. The impact of the intervention by glycaemic group did not show any phenotypic differences in response between NGT, IFG, and IGT. A hierarchical cluster analysis of change in glucose tolerance identified four sub-groups of “responders” (high and moderate) and “non-responders” (no response or deteriorated) but there were few differences in baseline clincal and physiological parameters or in response to the intervention to explain the overall variance. A further PCA analysis of 19 clinical and physiological univariables could explain less than half (48%) of total variability.Conclusion: We found that phenotypic characteristics from standard clinical and physiological parameters were not sufficient to account for the inter-individual variability in glucose tolerance following a 12 weeks lifestyle intervention in inidivuals at high risk for type 2 diabetes. Further work is required to identify biomarkers that complement phenotypic traits and better predict the response to glucose tolerance

Regional impacts of warming on biodiversity and biomass in high latitude stream ecosystems across the Northern Hemisphere

Warming can have profound impacts on ecological communities. However, explorations of how differences in biogeography and productivity might reshape the effect of warming have been limited to theoretical or proxy-based approaches: for instance, studies of latitudinal temperature gradients are often conflated with other drivers (e.g., species richness). Here, we overcome these limitations by using local geothermal temperature gradients across multiple high-latitude stream ecosystems. Each suite of streams (6-11 warmed by 1-15°C above ambient) is set within one of five regions (37 streams total); because the heating comes from the bedrock and is not confounded by changes in chemistry, we can isolate the effect of temperature. We found a negative overall relationship between diatom and invertebrate species richness and temperature, but the strength of the relationship varied regionally, declining more strongly in regions with low terrestrial productivity. Total invertebrate biomass increased with temperature in all regions. The latter pattern combined with the former suggests that the increased biomass of tolerant species might compensate for the loss of sensitive species. Our results show that the impact of warming can be dependent on regional conditions, demonstrating that local variation should be included in future climate projections rather than simply assuming universal relationships

Urbanisation affects ecosystem functioning more than structure in tropical streams

Urbanisation poses a clear threat to tropical freshwater streams, yet fundamental knowledge gaps hinder our ability to effectively conserve stream biodiversity and preserve ecosystem functioning. Here, we studied the impact of urbanisation on structural and functional ecosystem responses in low-order streams in Singapore, a tropical city with a mosaic landscape of protected natural forests, managed buffer zones (between forest and open-country habitats), and built-up urban areas. We quantified an urbanisation gradient based on landscape, in-stream, and riparian conditions, and found an association between urbanisation and pollution-tolerant macroinvertebrates (e.g. freshwater snail and worm species) in litter bags. We also found greater macroinvertebrate abundance (mean individuals bag−1; forest: 30.3, buffer: 70.1, urban: 109.0) and richness (mean taxa bag−1; forest: 4.53, buffer: 4.75, urban: 7.50) in urban streams, but similar diversity across habitats. Higher levels of primary productivity (measured from algal accrual on ceramic tiles) and microbial decomposition (measured from litter-mass loss in mesh bags) at urban sites indicate rapid microbial activity at higher light, temperature, and nutrient levels. We found that urbanisation affected function 32% more than structure in the studied tropical streams, likely driven by greater algal growth in urban streams. These changes in ecological processes (i.e. ecosystem functioning) possibly lead to a loss of ecosystem services, which would negatively affect ecology, society, and economy. Our results point to possible management strategies (e.g. increasing vegetation density through buffer park creation) to reduce the impacts of urbanisation, restore vital ecosystem functions in tropical streams, and create habitat niches for native species

Body Size Distribution of the Dinosaurs

The distribution of species body size is critically important for determining resource use within a group or clade. It is widely known that non-avian dinosaurs were the largest creatures to roam the Earth. There is, however, little understanding of how maximum species body size was distributed among the dinosaurs. Do they share a similar distribution to modern day vertebrate groups in spite of their large size, or did they exhibit fundamentally different distributions due to unique evolutionary pressures and adaptations? Here, we address this question by comparing the distribution of maximum species body size for dinosaurs to an extensive set of extant and extinct vertebrate groups. We also examine the body size distribution of dinosaurs by various sub-groups, time periods and formations. We find that dinosaurs exhibit a strong skew towards larger species, in direct contrast to modern day vertebrates. This pattern is not solely an artefact of bias in the fossil record, as demonstrated by contrasting distributions in two major extinct groups and supports the hypothesis that dinosaurs exhibited a fundamentally different life history strategy to other terrestrial vertebrates. A disparity in the size distribution of the herbivorous Ornithischia and Sauropodomorpha and the largely carnivorous Theropoda suggests that this pattern may have been a product of a divergence in evolutionary strategies: herbivorous dinosaurs rapidly evolved large size to escape predation by carnivores and maximise digestive efficiency; carnivores had sufficient resources among juvenile dinosaurs and non-dinosaurian prey to achieve optimal success at smaller body size. © 2012 O'Gorman, Hone

Log₁₀(femur length)-log₁₀(body mass) relationships for three major dinosaur clades: (a) Ornithischia (<i>y</i> = 3.0587<i>x</i>−2.7042; <i>r</i>² = 0.93), (b) Sauropodomorpha (<i>y</i> = 2.3459<i>x</i>−0.2935; <i>r</i>² = 0.73) and (c) Theropoda (<i>y</i> = 3.1854<i>x</i>−3.1840; <i>r</i>² = 0.97).

<p>The data sources for these relationships are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0051925#pone-0051925-t001" target="_blank">Table 1</a>.</p

Dinosaur taxa constituting the femur length-body mass relationships shown in Fig. 1, along with specimen numbers (where available), mass (in kg), femur length (FL in mm), source of mass measurement and reference to the paper containing the FL and mass estimate.

<p>Note that just 77 dinosaur species were identified in the literature with combined femur length and body mass estimates. Maximum femur lengths from a total of 329 species were used in the exploration of dinosaur body size distributions and these data are available on request from the authors.</p>*<p>Note that <i>Anatosaurus copei</i> is now identified as <i>Edmontosaurus annectens</i> and <i>Brachiosaurus brancai</i> is now known as <i>Giraffatitan brancai</i>. In this table, we report the species names as listed in the original referenced publication for ease of cross referencing. This includes a number of dinosaur genera that do not contain species names in the original paper.</p

Exploration of body size distributions for major vertebrate groups, dinosaur clades, time periods and formations.

<p>Values are given for skewness of the distribution, location of modes in the distribution, Lilliefors <i>D</i> statistic and the <i>p</i> value showing significant difference from a normal distribution.</p