[R-sig-eco] Mantel() with strata
Hi all Im 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. Im 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 dont 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 [[alternative HTML version deleted]] ___ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
[R-sig-eco] FW: betadisper
Dear all I'm using betadisper () to evaluate if geographical and historical heterogeneity differ statistically between two archipelagos. I have not problems in obtaining the results for the geographical hypothesis (computing the Euclidean distance between UTM centroids of each island), but for the historical hypothesis the following message appears: Error en vectors[, want, drop = FALSE] %*% diag(sqrt(abs(eig))) : argumentos no compatibles I calculate the historical triangular matrix computing the Euclidean distance between the oldest geological age of each island (all of them are from volcanic origin). I've also tried calculating just the difference in mya between all pairwise comparisons of islands, which gives basically the same results (but with different scaling). Can anybody help me with this problem? Thank you in advance Silvia [[alternative HTML version deleted]] ___ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
