Forward Selection of Explanatory Variables

Blanchet, F. Guillaume; Legendre, Pierre; Borcard, Daniel

doi:10.1890/07-0986.1

Cited by 1,816 publications

(1,347 citation statements)

References 28 publications

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“…Prior to the analysis, we used a forward selection procedure to limit the number of MEM variables included to those which described significant variation only. Forward selection was implemented using “vegan” and employed the double stopping criterion of Blanchet, Legendre, and Borcard (2008) to reduce the chance of false positives and overestimation of explained variance. A total of six MEMs explaining 39.9% of the total variation were thus selected.…”

Section: Methodsmentioning

confidence: 99%

Capturing genetic variation in crop wild relatives: An evolutionary approach

Egan

Muola

Stenberg

2018

Evolutionary Applications

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Crop wild relatives (CWRs) offer novel genetic resources for crop improvement. To assist in the urgent need to collect and conserve CWR germplasm, we advance here the concept of an “evolutionary” approach. Central to this approach is the predictive use of spatial proxies of evolutionary processes (natural selection, gene flow and genetic drift) to locate and capture genetic variation. As a means to help validate this concept, we screened wild‐collected genotypes of woodland strawberry (Fragaria vesca) in a common garden. A quantitative genetic approach was then used to test the ability of two such proxies—mesoclimatic variation (a proxy of natural selection) and landscape isolation and geographic distance between populations (proxies of gene flow potential)—to predict spatial genetic variation in three quantitative traits (plant size, early season flower number and flower frost tolerance). Our results indicated a significant but variable effect of mesoclimatic conditions in structuring genetic variation in the wild, in addition to other undetermined regional scale processes. As a proxy of gene flow potential, landscape isolation was also a likely determinant of observed patterns—as opposed to, and regardless of, geographic distance between populations. We conclude that harnessing proxies of adaptive and nonadaptive evolutionary processes could provide a robust and valuable means to identify genetic variation in CWRs. We thus advocate wider use and development of this approach amongst researchers, breeders and practitioners, to expedite the capture and in situ conservation of genetic resources provided by crop wild relatives.

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Section: Methodsmentioning

confidence: 99%

Capturing genetic variation in crop wild relatives: An evolutionary approach

Egan

Muola

Stenberg

2018

Evolutionary Applications

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“…Then, forward selection procedure was performed to select MEMs which had significant influence on algal richness or abundance with the function 'forward.sel' in 'packfor' package. This method using significance level of 0.05 and the adjusted-R 2 (R 2 adj ) of the global test as double stopping criteria prevents the problem of inflation of the overall type I error and avoids excessive variables from being included in the analysis (Blanchet et al 2008). The remaining MEMs were used as spatial variables included in the final RA and RDA.…”

Section: Statistical Analysesmentioning

confidence: 99%

Disentangling the roles of spatial and environmental variables in shaping benthic algal assemblages in rivers of central and northern China

Tang

et al. 2013

Aquat Ecol

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Benthic algae were collected from central and northern Chinese rivers to test the hypothesis that geographic location has significant contributions in shaping algal assemblages. We used Moran's eigenvector maps (MEM) to model spatial components and variation partitioning to quantify the influences of spatial and environmental variables on regional patterns of algal richness and community composition, respectively. We found that variation in algal richness was attributed to MEM component 2, 8, and 9 and the quadratic term of N-NO 3 . Regarding abundance data, latitude, longitude, and MEM component 1, 2, and 7 were important spatial variables. Although P-PO 4 , pH, and annual mean temperature were significant environmental variables influencing algal community composition, they were all spatially structured. Among the total explained variance in both algal metrics, spatial proportions were higher than that of environmental variables. We also found that abundant species of Achnanthidium minutissimum, Cocconeis placentula, Cymbella delicatula, Cymbella affinis, Cymbella turgidula, and Synedra ulna displayed clear spatially related patterns. In conclusion, the contributions of spatial and environmental variables to regional variation of algal assemblages are scaledependent. As for our study scale (*1,000 km), spatial control may be more important. Since spatial effects could obscure local environmental impacts on algal communities, appropriate study scale and statistical methods should be taken into account in algal bioassessment. We recommend inclusion of both algal richness and community composition in study of algal Handling Editor: Piet Spaak

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“…For coastal areas, this evaluation should be based on both physicochemical elements and biological indicators such as phytoplankton, macroalgae, benthic macrofauna, and seagrasses. Above all, benthic invertebrates are considered powerful indicators of marine pollution due to their sedentarism, long lives, easy sampling, and to the existence of extensive literature on their distribution in specific environments and on their response to different environmental stresses (Reish et al, 1999;Fano et al, 2003;Blanchet et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Effects of sewage pollution on the structure of rocky shore macroinvertebrate assemblages

et al. 2013

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The urgency to find efficient indices and indicators to prevent further deterioration of coastal areas is one of the hot topics in today's scientific publication. However, a detailed knowledge of community responses to anthropogenic impacts is essential to sustain those indices. The studies on the response of benthic community to sewage pollution on intertidal rocky shores are generally based on visual census and do not take into account the tidal levels. In order to fulfil this gap in this study: (i) the sampling was performed by destructive sampling, with all individuals identified to the species level; (ii) the sampling was done at all levels of the intertidal (sublittoral fringe, eulittoral, and littoral fringe). Sewage pollution changed the environmental variables and the abundance of macroinvertebrates, being Mytilus galloprovincialis, Melarhaphe neritoides, and Chthamalus montagui the species most responsible for the dissimilarities observed. Effects were different on the three intertidal zones: community structure changed in the sublittoral fringe; suspensionfeeders abundances and species richness increased in the eulittoral; no differences were detected in the littoral fringe. Moreover, the results confirm that the presence of sewage discharges tended to benefit suspension feeders, and that the sensitive species were replaced by opportunistic ones.

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Forward Selection of Explanatory Variables

Cited by 1,816 publications

References 28 publications

Capturing genetic variation in crop wild relatives: An evolutionary approach

Capturing genetic variation in crop wild relatives: An evolutionary approach

Disentangling the roles of spatial and environmental variables in shaping benthic algal assemblages in rivers of central and northern China

Effects of sewage pollution on the structure of rocky shore macroinvertebrate assemblages

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