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

[Martin Weiser]

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.