100 research outputs found
How to allow SAR collapse across local and continental scales: a resolution of the controversy between Storch et al. (2012) and Lazarina et al. (2013)
Up-scaling species richness from local to continental scales is an unsolved problem of macroecology. Macroecologists hope that proper up-scaling can uncover the hidden rules that underlie spatial patterns in species richness, but a machinery to up-scale species richness also has a purely practical side at the scales and for the habitats where direct observations cannot be performed. The species–area relationship (SAR) could provide a tool for up-scaling, but no valid method has yet been put forward. Such a method would have resulted from Storch et al.’s (2012) suggestion that there is a universal curve to which each rescaled SAR collapses, if Lazarina et al. (2013) had not shown that it does not: both arguments were supported by data analyses. Here we present an analytical model for mainland SAR and argue in favour of the latter authors. We identify (i) the variation in mean species-range size, (ii) the variation in forces that drive SAR at various scales, and (iii) the finite-area effect, as the reasons for the absence of collapse. Finally, we suggest a rescaling that might fix the problem. We conclude, however, that ecologists are still far from finding a practical, robust and easy-to-use solution for up-scaling species richness from SARs
Species abundance distribution results from a spatial analogy of central limit theorem
Copyright © 2009, The National Academy of SciencesThe frequency distribution of species abundances [the species abundance distribution (SAD)] is considered to be a fundamental characteristic of community structure. It is almost invariably strongly right-skewed, with most species being rare. There has been much debate as to its exact properties and the processes from which it results. Here, we contend that an SAD for a study plot must be viewed as spliced from the SADs of many smaller nonoverlapping subplots covering that plot. We show that this splicing, if applied repeatedly to produce subplots of progressively larger size, leads to the observed shape of the SAD for the whole plot regardless of that of the SADs of those subplots. The widely reported shape of an SAD is thus likely to be driven by a spatial parallel of the central limit theorem, a statistically convergent process through which the SAD arises from small to large scales. Exact properties of the SAD are driven by species spatial turnover and the spatial autocorrelation of abundances, and can be predicted using this information. The theory therefore provides a direct link between SADs and the spatial correlation structure of species distributions, and thus between several fundamental descriptors of community structure. Moreover, the statistical process described may lie behind similar frequency distributions observed in many other scientific fields
Can people change the ecological rules that appear general across space?
Aim: The projections of human impact on the environment and biodiversity patterns are crucial if we are to prevent their destruction. Such projections usually involve the assumption that the same human activities always affect biodiversity in the same way either in geographically distant areas within the same time scale or in the same areas in different periods. In this paper, plant and snail fossils from Central Europe that cover the last 12,000 years provide evidence against this assumption. Location: Central Europe. Methods: We examined fossil data on central European plants and snails and extracted time-series of (1) local species richness (alpha diversity) at a scale of approximately 300 m × 300 m and decays of (2) the Jaccard index and (3) Simpson's beta with increasing distance (up to approximately 400 km) through time. Results: We show that two vital biodiversity patterns follow neither oxygen-isotope nor borehole temperature proxies, but instead vary between archaeologically known periods, with the most noticeable and irreversible breaks (1) when arable agriculture was introduced into central Europe, (2) when the Roman Empire collapsed, and (3) during the event known as the 12th-century colonization in central Europe. The patterns computed from data across time sometimes contradicted the patterns computed across space. Main Conclusions: We therefore infer that people can, and sometimes have, contributed to temporal changes in ecological rules that are seemingly general across space. Our findings indicate that the changes in ecological rules are so substantial that efforts to project future biodiversity based on space-for-time substitution might fail, unless we gain knowledge about how these general rules are altered
The species-area relationship and evolution
Models relating to the Species-Area curve are usually defined at the species
level, and concerned only with ecological timescales. We examine an
individual-based model of co-evolution on a spatial lattice based on the
Tangled Nature model, and show that reproduction, mutation and dispersion by
diffusion in an interacting system produces power-law Species-Area Relations as
observed in ecological measurements at medium scales. We find that
co-evolutionary habitats form, allowing high diversity levels in a spatially
homogenous system, and these are maintained for exponentially increasing time
when increasing system size.Comment: 21 pages, 5 figures. This is the final, accepted draf
Upscaling biodiversity: estimating the species–area relationship from small samples
The challenge of biodiversity upscaling, estimating the species richness of a large area from scattered local surveys within it, has attracted increasing interest in recent years, producing a wide range of competing approaches. Such methods, if successful, could have important applications to multi‐scale biodiversity estimation and monitoring. Here we test 19 techniques using a high quality plant data set: the GB Countryside Survey 1999, detailed surveys of a stratified random sample of British landscapes. In addition to the full data set, a set of geographical and statistical subsets was created, allowing each method to be tested on multiple data sets with different characteristics. The predictions of the models were tested against the “true” species–area relationship for British plants, derived from contemporaneously surveyed national atlas data. This represents a far more ambitious test than is usually employed, requiring 5–10 orders of magnitude in upscaling. The methods differed greatly in their performance; while there are 2,326 focal plant taxa recorded in the focal region, up‐scaled species richness estimates ranged from 62 to 11,593. Several models provided reasonably reliable results across the 16 test data sets: the Shen and He and the Ulrich and Ollik models provided the most robust estimates of total species richness, with the former generally providing estimates within 10% of the true value. The methods tested proved less accurate at estimating the shape of the species–area relationship (SAR) as a whole; the best single method was Hui's Occupancy Rank Curve approach, which erred on average by <20%. A hybrid method combining a total species richness estimate (from the Shen and He model) with a downscaling approach (the Šizling model) proved more accurate in predicting the SAR (mean relative error 15.5%) than any of the pure upscaling approaches tested. There remains substantial room for improvement in upscaling methods, but our results suggest that several existing methods have a high potential for practical application to estimating species richness at coarse spatial scales. The methods should greatly facilitate biodiversity estimation in poorly studied taxa and regions, and the monitoring of biodiversity change at multiple spatial scales
An Alternative Theoretical Approach to Escape Decision-Making: The Role of Visual Cues
Escape enables prey to avoid an approaching predator. The escape decision-making process has traditionally been interpreted using theoretical models that consider ultimate explanations based on the cost/benefit paradigm. Ultimate approaches, however, suffer from inseparable extra-assumptions due to an inability to accurately parameterize the model's variables and their interactive relationships. In this study, we propose a mathematical model that uses intensity of predator-mediated visual stimuli as a basic cue for the escape response. We consider looming stimuli (i.e. expanding retinal image of the moving predator) as a cue to flight initiation distance (FID; distance at which escape begins) of incubating Mallards (Anas platyrhynchos). We then examine the relationship between FID, vegetation cover and directness of predator trajectory, and fit the resultant model to experimental data. As predicted by the model, vegetation concealment and directness of predator trajectory interact, with FID decreasing with increased concealment during a direct approach toward prey, but not during a tangential approach. Thus, we show that a simple proximate expectation, which involves only visual processing of a moving predator, may explain interactive effects of environmental and predator-induced variables on an escape response. We assume that our proximate approach, which offers a plausible and parsimonious explanation for variation in FID, may serve as an evolutionary background for traditional, ultimate explanations and should be incorporated into interpretation of escape behavior
Knitting patterns of biodiversity, range size and body size in aquatic beetle faunas : significant relationships but slightly divergent drivers
1. Ecogeographical rules refer to recurring patterns in nature, including the latitudinal diversity gradient (LDG), Rapoport's rule and Bergmann's rule, amongst others. In the present study, the existence of these rules was examined for diving beetles (Coleoptera: Dytiscidae), a family of aquatic predatory beetles.
2. Assemblage-level data were analysed for diving beetles, focusing on species richness, local contribution to beta diversity (LCBD), mean range size and mean body size across the biogeographical provinces of Northern Europe. First, each of these variables was correlated with latitude, and then variation in each variable was modelled using actual environmental variables in boosted regression tree analysis.
3. Species richness was found to decrease with latitude, LCBD increased with latitude, mean range size did not show a significant relationship with latitude, and mean body size decreased with latitude. The latter finding was in contrast to Bergmann's rule. The actual environmental variables best predicting variation in these four response variables varied among the models, although they generally included temperature-related and land use variables as the most influential ones.
4. The results obtained in the present study suggest that diving beetles conformed to the LDG, did not follow Rapoport's rule, and showed a reversed latitudinal gradient in the context of Bergmann's rule. In addition, species-poor provinces harboured ecologically most unique faunas, suggesting that species richness and LCBD are complementary measures of biodiversity.
5. Even though general support was not found for most of the ecogeographical rules examined, the findings of the present study are interesting because they suggest that aquatic ectothermic invertebrates may show patterns different from those originally described for terrestrial endothermic vertebrates
Energetic Structure Synergy in Industry 4.0
Diplomová práce obsahuje představení technických zařízení budov ve spojení s internetem věcí a Industry 4.0. Hlavním cílem je nalezení a aplikování synergie zařízení pro energetickou úsporu. Výsledkem práce je návrh expertního systému pro komplexní regulaci nevýrobních zařízení.ObhájenoThe diploma thesis contains an introduction to the technical equipment of buildings in connection with the Internet of Things and Industry 4.0. The main goal is to find and apply the synergy of energy saving devices. The result of the work is the design of an expert system for complex regulation of non-production equipment
Possibilities of industrial control
Bakalářská práce obsahuje představení technických zařízení budov a technické zhodnocení vhodnosti pro napojení na průmyslovou regulaci. Druhá část práce obsahuje návrh a aplikaci řídicího systému. Závěr práce obsahuje energetické zhodnocení úspor.ObhájenoBachelor thesis is dedicated to technical equipment of buildings and an evaluation of the applicability of regulation in the industrial area.The second part of the thesis presents draft and practical application of the operational system.
The thesis concludes with the evaluation of energy savings
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