Hi all
I’m computing mantel test between species
dissimilarity and geographic distance between all pairwise island comparisons
in three archipelagos (each with 9, 7 and 3 islands) within the same
biogeographical region. I’m using mantel() of vegan package, and I was
wondering if I should use the strata argument to control for the archipelago
effect. Does anyone know if using ‘archipelago’ as random effect with only 3
levels is enough to obtain reliable estimates of variance? I don’t think so.
Instead, if in the same scatter plot of species dissimilarity vs geographic
distance I mark differently the points corresponding to within-archipelago and
between-archipelago comparisons, how can I test (through permutations) the
statistical significance of both correlations?
Any input on this issue will be ok for me!
Thank you in advance 		 	   		  
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