[R-sig-eco] adehabitat and Lat Long data
Hi I have ARGOS satellite tag data from some some very long distance traveling sharks. These critters cover large chunks of the Atlantic; coordinates are in decimal degrees. It would love to apply the residenceTime function in the adehabitat package to try and segment the paths into broad homogeneous bouts of movement (i.e. migration, seasonal residence/feeding areas etc). But as far as I can tell from the documentation and the examples it seems that the data must be in some sort of Cartesian coordinate system. Conversion to UTM's wouldn't be practical in this case because the movement tracks encompass many UTM zones. Is there a way to do the residence time analysis in adehabitat using data in decimal degrees that perhaps I am just missing? If not, does anybody have any code or recommendations for another way to go about this? Any insight appreciated! Thanks -Mike -- View this message in context: http://r-sig-ecology.471788.n2.nabble.com/adehabitat-and-Lat-Long-data-tp7577571.html Sent from the r-sig-ecology mailing list archive at Nabble.com. ___ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
Re: [R-sig-eco] adehabitat and Lat Long data
Hello Mike, One approach may be to convert your coordinates to a custom continuous equidistant conic projection with a central meridian near the center of your coordinates. This should help minimize errors in distances calculated across a large area. Hope that is useful. Cheers, Jeff -- View this message in context: http://r-sig-ecology.471788.n2.nabble.com/adehabitat-and-Lat-Long-data-tp7577571p7577573.html Sent from the r-sig-ecology mailing list archive at Nabble.com. ___ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
[R-sig-eco] Multivariate ANOVA based on dissimilarities
Dear all, Im using the function adonis (multivariate ANOVA based on dissimilarities) to study beta diversity of moths between altitudinal levels and seasons. My analysis is based on the example included in the vegan tutorial Multivariate Analysis of Ecological Communities in R: vegan tutorial, written by Jari Oksanen. As in the example, the analysis of my data indicated that there are significant differences. However, the Tukeys test indicated that there are no differences between groups? Why does it happen? Shouldnt the Tukeys test show that one group is different from another? The script is almost the same of the tutorial but with more permutations. Thank you. Mauricio Permanova-read.table(Permanova.txt,header=T) PermanovaII-read.table(PermanovaII.txt,header=T) betad - betadiver(Permanova, z) adonis(formula = betad ~ Altitude*Season,data = PermanovaII, permutations = 1000) hov - with(PermanovaII, betadisper(betad, Altitude)) TukeyHSD(hov) hovII - with(PermanovaII, betadisper(betad, Season)) TukeyHSD(hovII) [[alternative HTML version deleted]] ___ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
Re: [R-sig-eco] Multivariate ANOVA based on dissimilarities
Mauricio, Nothing reproducible here (we don't have your data sets), not even the output. In your email you only write about adonis() and the p-values you got from adonis. On the other hand, your TukeyHSD() is based on betadisper(), and you never seem to check the betadisper() p-values. These two methods are radically different: adonis() is about differences between groups, and betadisper() is about dispersions within groups. We expect some kind of consistency between betadisper() p-values and TukeyHSD() of betadisper, but adonis() is quite a different beast which has little to do with betadisper(). If you take an analogy to standard statistics: adonis() is like (M)ANOVA, betadisper() is like Levene's test of homogeneity (what ever that means) of variances, and TukeyHSD() is its sequel about detecting cases with different variances. I suggest you rather use 999 permutations than 1000: you can get nicer round figures. Once we were more patronizing and dropped one permutation if the user asked for even hundred or thousand, but then we thought that this is up to user to decide and none of our business. Cheers, Jari Oksanen On 27/08/2012, at 23:23 PM, Maurício Moraes Zenker wrote: Dear all, I‚m using the function „adonis‰ (multivariate ANOVA based on dissimilarities) to study beta diversity of moths between altitudinal levels and seasons. My analysis is based on the example included in the vegan tutorial „Multivariate Analysis of Ecological Communities in R: vegan tutorial‰, written by Jari Oksanen. As in the example, the analysis of my data indicated that there are significant differences. However, the Tukey‚s test indicated that there are no differences between groups? Why does it happen? Shouldn‚t the Tukey‚s test show that one group is different from another? The script is almost the same of the tutorial but with more permutations. Thank you. Mauricio Permanova-read.table(Permanova.txt,header=T) PermanovaII-read.table(PermanovaII.txt,header=T) betad - betadiver(Permanova, z) adonis(formula = betad ~ Altitude*Season,data = PermanovaII, permutations = 1000) hov - with(PermanovaII, betadisper(betad, Altitude)) TukeyHSD(hov) hovII - with(PermanovaII, betadisper(betad, Season)) TukeyHSD(hovII) [[alternative HTML version deleted]] ___ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology -- Jari Oksanen, Dept Biology, Univ Oulu, 90014 Finland jari.oksa...@oulu.fi, Ph. +358 400 408593, http://cc.oulu.fi/~jarioksa ___ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
