scholarly journals Using trait data improves correlation between environment and community data only if abundances are considered

2021 ◽  
Author(s):  
Attila Lengyel ◽  
Sándor Barabás ◽  
Boglárka Berki ◽  
Anikó Csecserits ◽  
Adrienn Gyalus ◽  
...  
Keyword(s):  
Explanatory Power ◽  
Seed Mass ◽  
Analysis Data ◽  
Variance Partitioning ◽  
Procrustes Analysis ◽  
Geographical Distance ◽  
Spatial Variables ◽  
Environmental Matching ◽  
Variation Explained ◽  
Analysis Models

AbstractA straightforward way to explore variation between communities is to calculate dissimilarity indices and relate them with environmental and spatial variables. Communities are most often represented by the (relative) abundances of taxa they comprise; however, more recently, the distribution of traits of organisms included in the communities has been shown more strongly related to ecosystem properties. In this study, we test whether taxon- or trait-based dissimilarity is correlated more tightly with environmental difference and geographical distance and how the abundance scale influences this correlation. Our study system is grassland vegetation in Hungary, where we sampled vegetation plots spanning a long productivity gradient from open dry grasslands to marshes in three sites. We considered three traits for vascular plants: canopy height, specific leaf area and seed mass. We obtained field estimates of normalized vegetation difference index (NDVI) as proxy of productivity (water availability) for each plot. We calculated between-community dissimilarities using a taxon-based and a trait-based index, using raw and square-root transformed abundances and presence/absence data. We fitted distance-based redundancy analysis models with NDVI difference and geographical distance on the dissimilarity matrices and evaluated them using variance partitioning. Then, using the pooled data, we calculated non-metric multidimensional scaling ordinations (NMDS) from all types of dissimilarity matrices and made pairwise comparisons using Procrustes analysis. Data analysis was done separately for the three sites.We found that taxonomical dissimilarity matches environmental and spatial variables better when presence/absence data is used instead of abundance. This pattern was mainly determined by the increasing variation explained by space at the presence/absence scale. In contrast to this trend, with trait-based dissimilarity, accounting for abundance increased explained variation significantly due to the higher explanatory power of NDVI. With abundance data, considering traits improved environmental matching to a great extent in comparison with taxonomical information. However, with presence/absence data, traits brought no advantage over taxon-based dissimilarity in any respect. Changing the abundance scale caused larger difference between ordinations in the case of trait-based dissimilarity than with taxonomical dissimilarity.We conclude that considering relevant traits improves environmental matching only if abundances are also accounted for.Supporting informationAdditional graphs supporting the results are presented as appendix.Open researchData used in this research are publicly available from Dryad ###link to be supplied upon acceptance###

Ranking the explanatory power of factors associated with worldwide new Covid-19 cases

2021 ◽  
Author(s):  
Aristides Moustakas
Keyword(s):  
Explanatory Power ◽  
Interdisciplinary Approach ◽  
Time Frame ◽  
Variance Partitioning ◽  
Total Variance ◽  
Disease Spread ◽  
Spatial Spread ◽  
Global Pandemic ◽  
Governmental Intervention ◽  
Short Time

Abstract Disease spread is a complex phenomenon requiring an interdisciplinary approach. Covid-19 exhibited a global spatial spread in a very short time frame resulting in a global pandemic. Data of new Covid-19 cases per million were analysed worldwide at the spatial scale of a country and time replicated from the end of December 2019 to late May 2020. Data driven analysis of epidemiological, economic, public health, and governmental intervention variables was performed in order to select the optimal variables in explaining new Covid-19 cases across all countries in time. Sequentially, hierarchical variance partitioning of the optimal variables was performed in order to quantify the independent contribution of each variable in the total variance of new Covid-19 cases per million. Results indicated that from the variables available new tests per thousand explained the vast majority of the total variance in new cases (51.6%) followed by the governmental stringency index (15.2%). Availability of hospital beds per 100k inhabitants explained 9% extreme poverty explained 8.8%, hand washing facilities 5.3%, the fraction of the population aged 65 or older explained 3.9%, and other disease prevalence (cardiovascular diseases plus diabetes) explained 2.9%. The percentage of smokers within the population explained 2.6% of the total variance, while population density explained 0.6%.

scholarly journals Biodiversity response to natural gradients of multiple stressors on continental margins

2016 ◽  
Vol 283 (1829) ◽  
pp. 20160637 ◽  
Author(s):  
Erik A. Sperling ◽  
Christina A. Frieder ◽  
Lisa A. Levin
Keyword(s):  
Global Change ◽  
Regional Differences ◽  
Multiple Stressors ◽  
Explanatory Power ◽  
Variance Partitioning ◽  
Continental Margins ◽  
Faunal Change ◽  
Ecological Shifts ◽  
Secondary Stressors ◽  
Sharp Thresholds

Sharp increases in atmospheric CO 2 are resulting in ocean warming, acidification and deoxygenation that threaten marine organisms on continental margins and their ecological functions and resulting ecosystem services. The relative influence of these stressors on biodiversity remains unclear, as well as the threshold levels for change and when secondary stressors become important. One strategy to interpret adaptation potential and predict future faunal change is to examine ecological shifts along natural gradients in the modern ocean. Here, we assess the explanatory power of temperature, oxygen and the carbonate system for macrofaunal diversity and evenness along continental upwelling margins using variance partitioning techniques. Oxygen levels have the strongest explanatory capacity for variation in species diversity. Sharp drops in diversity are seen as O 2 levels decline through the 0.5–0.15 ml l −1 (approx. 22–6 µM; approx. 21–5 matm) range, and as temperature increases through the 7–10°C range. p CO 2 is the best explanatory variable in the Arabian Sea, but explains little of the variance in diversity in the eastern Pacific Ocean. By contrast, very little variation in evenness is explained by these three global change variables. The identification of sharp thresholds in ecological response are used here to predict areas of the seafloor where diversity is most at risk to future marine global change, noting that the existence of clear regional differences cautions against applying global thresholds.

The relative importance of natural and anthropogenic effects on community composition of aquatic macrophytes in Mediterranean ponds

2011 ◽  
Vol 62 (2) ◽  
pp. 101 ◽  
Author(s):  
Rocío del Pozo ◽  
Camino Fernández-Aláez ◽  
Margarita Fernández-Aláez
Keyword(s):  
Community Composition ◽  
Submerged Macrophytes ◽  
Anthropogenic Impacts ◽  
Natural Habitat ◽  
Ecological Status ◽  
Variance Partitioning ◽  
Anthropogenic Effects ◽  
Relative Importance ◽  
Study Support ◽  
Variation Explained

To detect when changes in response to stressors are occurring, biomonitoring programs require an understanding of shifts in biota that occur in response to anthropogenic and natural effects. Aquatic plants are expected to reflect the environmental conditions of ponds and, according to the European Water Framework Directive, macrophytes should be considered in ecological status assessments of inland surface waters. We assessed the relative importance of natural and anthropogenic impacts on submerged, emergent and floating-leaved macrophytes in 44 ponds in Duero river basin (North Iberian Plateau). Constrained canonical ordinations included 15 taxa of submerged macrophytes and 24 species of emergent and floating-leaved macrophytes. Although the proportion of variation explained by all selected variables was relatively low (37%), we found that submerged community composition reflected the influence of natural (habitat and biotic variables) and anthropogenic effects. However, emergent and floating-leaved macrophytes were not influenced by biotic variables. Variance partitioning showed that degradation category was the best predictor of both submerged macrophytes and emergent and floating-leaved macrophyte composition. However, submerged macrophytes were more affected by chemical variables, whereas emergent and floating-leaved macrophyte composition was best explained by land-use variables. The results of this study support the use of macrophyte communities as effective indicators of the ecological status of Mediterranean ponds.

scholarly journals Which Seed Properties Determine the Preferences of Carabid Beetle Seed Predators?

Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 757
Author(s):  
Foffová Hana ◽  
Ćavar Zeljković Sanja ◽  
Honěk Alois ◽  
Martinková Zdenka ◽  
Tarkowski Petr ◽  
...  
Keyword(s):  
Seed Coat ◽  
Explanatory Power ◽  
Seed Mass ◽  
Carabid Beetles ◽  
Plant Strategy ◽  
Seed Predators ◽  
Lack Of Information ◽  
Complete Set ◽  
Morphological Defence ◽  
Explained Variance

Ground beetles are important invertebrate seed predators in temperate agro-ecosystems. However, there is a lack of information regarding which seed properties are important to carabids when they select seeds for consumption. Therefore, seed properties, such as size, shape, morphological defence, and chemical composition, were measured, and in addition to seed taxonomy and ecology, these data were used to explain carabid preferences. Carabid preferences were assessed using a multi-choice experiment with 28 species of weed seeds presented to 37 species of Carabidae. Multiple regression on distance matrices (MRM) was used to determine the importance of particular sets of seed properties for carabids. The analysis was conducted for the full set of carabids (37 species) as well as for subsets of species belonging to the tribes of Harpalini or Zabrini. For the complete set of species, seed dimensions, seed mass, taxonomy, plant strategy, and seed coat properties significantly explained carabid preferences (proportion of explained variance, R2 = 0.465). The model for Harpalini fit the data comparably well (R2 = 0.477), and seed dimensions, seed mass and seed coat properties were significant. In comparison to that for Harpalini, the model for Zabrini had much lower explanatory power (R2 = 0.248), and the properties that significantly affected the preferences were seed dimensions, seed mass, taxonomy, plant strategy, and seed coat properties. This result suggests that the seed traits that carabids respond to may be specific to taxonomic and likely relate to the degree of specialisation for seeds. This study contributes to understanding the mechanisms that determine the preferences of carabid beetles for seeds.

Technological Innovation, Trade and Development

2011 ◽  
pp. 79-101
Author(s):  
Laura Márquez-Ramos ◽  
Inmaculada Martínez-Zarzoso ◽  
Celestino Suárez-Burguet
Keyword(s):  
Developing Countries ◽  
Economic Policy ◽  
Economic Development ◽  
International Trade ◽  
Technological Innovation ◽  
Explanatory Power ◽  
Geographical Distance ◽  
Technological Capabilities ◽  
Level Of Economic Development

This chapter tests empirically to what extent technological innovation influences international trade and studies its effect on different groups of countries according to their level of economic development. Different measures used in the literature to proxy for technological capabilities are reviewed and two of them are selected. The estimation results show that technological innovation has a considerably high explanatory power on trade compared with other traditional determinants. Countries tend to trade more when they have similar technological capabilities and the development of technological innovation has lowered the effect of geographical distance on trade. According to the obtained results, investing in technological innovation leads to the improvement and maintenance of the level of competitiveness, therefore a good economic policy in developing countries is to invest in technological innovation.

Advanced Procrustes Analysis Models in Photogrammetric Computer Vision

2019 ◽  
Author(s):  
Fabio Crosilla ◽  
Alberto Beinat ◽  
Andrea Fusiello ◽  
Eleonora Maset ◽  
Domenico Visintini
Keyword(s):  
Computer Vision ◽  
Procrustes Analysis ◽  
Analysis Models

Environmental associations of sponges in the Spermonde Archipelago, Indonesia

2007 ◽  
Vol 87 (6) ◽  
pp. 1669-1676 ◽  
Author(s):  
Daniel F.R. Cleary ◽  
Nicole J. de Voogd
Keyword(s):  
Environmental Variables ◽  
Sediment Load ◽  
Community Similarity ◽  
Spatial Variables ◽  
South West ◽  
Spatial Turnover ◽  
Reef Environments ◽  
Environmental Component ◽  
Variation Explained ◽  
Spermonde Archipelago

Relatively little is known about spatial turnover of marine benthic taxa in the diverse reef environments of Indonesia and how this is structured by environmental conditions. In the present study the community similarity of sponges was related to environmental and spatial variables. In total, 150 sponge species (N=15,842) were sampled within the Spermonde Archipelago in the Makassar Strait, off south-west Sulawesi. Ordination revealed that sponges are primarily structured by a complex interaction between depth, exposure and on-to-offshore variation in environmental variables. Together, environmental and spatial variables explained 56.9% of the variation in similarity of which 10.9% was due to environmental variables alone, 2.6% due to spatial variables alone and 43.4% due to covariation of environmental and spatial variables. The large amount of variation explained by the spatially structured environmental component is due to a strong on-to-offshore gradient in a number of environmental variables including temperature, velocity, salinity and suspended sediment load. Ordination was also used to identify associations between species and environmental variables.

SEED SET AND SEED MASS INIPOMOPSIS AGGREGATA: VARIANCE PARTITIONING AND INFERENCES ABOUT POSTPOLLINATION SELECTION

Evolution ◽  
1995 ◽  
Vol 49 (1) ◽  
pp. 80-88
Author(s):  
Nickolas M. Waser ◽  
Ruth G. Shaw ◽  
Mary V. Price
Keyword(s):  
Seed Set ◽  
Seed Mass ◽  
Variance Partitioning

Seed-coat thickness data clarify seed size–seed-bank persistence trade-offs inAbutilon theophrasti(Malvaceae)

2014 ◽  
Vol 24 (2) ◽  
pp. 119-131 ◽  
Author(s):  
Brian J. Schutte ◽  
Adam S. Davis ◽  
Stephen A. Peinado ◽  
Jamshid Ashigh
Keyword(s):  
Seed Size ◽  
Seed Coat ◽  
Seed Bank ◽  
Explanatory Power ◽  
Seed Mass ◽  
Trade Offs ◽  
Selection For ◽  
Viable Seeds ◽  
Seed Coats ◽  
Size Data

AbstractTheoretical models predict that seed size and seed-bank persistence evolve interdependently, such that strong selection for one trait corresponds with weak selection for the other. This framework has been supported and rejected by empirical data, and thus, conclusive evidence is lacking. We expanded the seed size–persistence framework to include seed-coat thickness, a defence trait previously correlated with seed survival in soil. To do this, we usedAbutilon theophrastiaccessions with varied evolutionary histories and we quantified associations among seed traits including morphology, size, coat thickness, dormancy (percentage of viable seeds that fail to germinate under optimum conditions) and seed-bank persistence (percentage of viable seeds remaining after 1 year of burial). Statistical models were developed to test the hypothesis that combined measurements of seed-coat thickness and seed size better explain variability in seed-bank persistence than seed-size data alone. Results indicated that measurements of seed size (length, width, mass) were negatively correlated with coat:width ratio (coat thickness relative to seed width) and coat:mass ratio (coat thickness relative to seed mass). Accessions characterized by smaller seeds with proportionally thicker seed coats were more dormant and more persistent in soil than accessions characterized by larger seeds with proportionally thinner seed coats. Seed-coat thickness data improved the explanatory power of logistic regression models for seed-size effects on both seed-bank persistence and dormancy. These results indicate that supplementing seed-size data with seed-defence data may clarify previously reported contradictory results regarding trade-offs between seed size and seed-bank persistence.

Sign in / Sign up

Export Citation Format

Share Document