[R-sig-eco] Difference between mantel test and adonis

[v_coudrain at voila.fr]

Dear Martin, 
Tank you very much. I thought about constrained ordination, but the distance matrix I am using is not among the "usual" (Euclidian, Bray-Curtis,...). An option 
would be to use distance-based RDA, which is almost the same as adonis, but I read that adonis should be even better (?) Anyway I am mainly interested to 
understand the difference between analyses based on distance matrix of the environemental gradient (Mantel test), or on the gradient directly. 
Best,
Valérie


> Message du 16/01/13 à 00h53
> De : "Martin Weiser" 
> A : v_coudrain at voila.fr
> Copie à : r-sig-ecology at r-project.org
> Objet : Re: [R-sig-eco] Difference between mantel test and adonis
> 
> v_coudrain at voila.fr píše v Út 15. 01. 2013 v 16:08 +0100:
> > Dear sig-eco users,
> > 
> > I would like to investigate the changes in a species community along an ecological gradient. I first thought about performing a Mantel test and infer if 
differences in 
> > species composition are related to differences in the ecological gradient. I noticed that the function adonis (package vegan) could handle continuous 
variables as 
> > well. However, the ecological gradient is not entered as a distance matrix and therefore I don't understand exactly how to interpret the outcome of the adonis 
test 
> > and what is the difference to the Mantel test. Any help will be apprectiate.
> > 
> > Best wishes. Valerie
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> 
> Dear Valerie,
> I would go for constrained ordination: it is easily interpretable and
> tailored exactly to your needs.
> To do so, in R use ade4 or vegan (I am not familiar with ade4) and run
> CCA or RDA (depends on data and taste). Plus, Jari Oksanen wrote
> easy-to-understand tutorial:
> http://cc.oulu.fi/~jarioksa/opetus/metodi/vegantutor.pdf 
> Another great free resources are Mike Palmer's website:
> http://ordination.okstate.edu/ 
> and ordnews mailinglist:
> ordnews at colostate.edu
> I hope this helps.
> Best,
> Martin W.
> 
> 

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