Thank you for your kind response,
I am sorry about the lack of details behind my original question, I will explain now why is important to me to test for the among group combinations. Specifically, I have sampled apple orchards and two neighboring seminatural habitats (forest and grasslands). I am interested in evaluating how the community composition change across these different habitats. In particular, I expect that a significant interaction between the nestedness of two habitats will be an indicative of high spillover between these habitats. For instance, I have a distance matrix of the “relativized nestedness” of Podani and Schmera (2011) and I would like to test the contribution of forest and grassland habitats to the local diversity of apple orchards. Therefore, I would like to compute the variances in nestedness across these different habitats. For example, the “adonis” function in vegan does this work, but my problem is that I cannot test for the variance among habitats (following the original example it would be the *ba*, *ca*, and *cb* combinations). If I specify in “adonis” to do the grouping as *a*, *b* and *c*, it will do the test on the *aa*, *bb* and *cc* of the matrix. Is it a way to specify the groupings so that it will subset the distance matrix to test for *ba*, *ca* and *cb* combinations? Thank you, Diego 2014-09-18 17:29 GMT+02:00 Sarah Goslee <[email protected]>: > Test them for what? > > If you can formulate your hypotheses more clearly, you might try the > model matrix approach outlined in > > Legendre, P. and M.-J. Fortin. 1989. Spatial pattern and ecological > analysis. Vegetatio, 80: 107-138. > > and subsequent references. > > But there might be better ways, depending on what you are trying to > achieve. > > Sarah > > > On Thu, Sep 18, 2014 at 11:17 AM, Diego Javier Inclan Luna > <[email protected]> wrote: > > Hi, > > > > I would like to test dissimilarities among different groups in a dist > > matrix. For instance, if I have a dist matrix with three factors a, b, c, > > functions like adonis and betadisper in vegan will test the aa, bb and cc > > combinations. However, I am interested in testing the ba, ca, and cb > > combinations. How I could test for these combinations? > > > > > > *a a a b b b c c c* > > > > *a* aa > > *a* aa aa > > *a* aa aa aa > > *b* ba ba ba bb > > *b* ba ba ba bb bb > > *b* ba ba ba bb bb bb > > *c* ca ca ca cb cb cb cc > > *c* ca ca ca cb cb cb cc cc > > *c* ca ca ca cb cb cb cc cc cc > > > > > > Thanks! > > -- > -- > Sarah Goslee > http://www.functionaldiversity.org > -- ---- Diego J. Inclan PhD Student DAFNAE-Entomology, University of Padova Viale dell'Università 16, 35020, Legnaro (PD) - Italy webpage: http://www.biodiversity-lorenzomarini.eu/Diego.html [[alternative HTML version deleted]] _______________________________________________ R-sig-ecology mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
