Hi Zach.

Do you just mean the mean patristic distance among all pairwise combinations of species in each assemblage?

If you have your assemblages in a list of vectors, each containing the species of the corresponding assemblage, I think you could do:

d<-sapply(assemblages,function(sp,D) mean(as.dist(D[sp,sp])),D=D)

Does that work?

All the best, Liam

Liam J. Revell, Associate Professor of Biology
University of Massachusetts Boston
web: http://faculty.umb.edu/liam.revell/
email: liam.rev...@umb.edu
blog: http://blog.phytools.org

On 2/2/2017 3:22 PM, Zach Culumber wrote:
Hi everyone,

I have a time-calibrated phylogeny with ~100 species and a list of ~1000
observed species assemblages which vary from 2-20 species in size.  I'd
like to get the mean phylogenetic distance among species in each
assemblage, but I'm having difficulty finding a way to do this.  The
comm.phylo.cor command in picante throws an error in as.hclust.default(x),
that x cannot be coerced to class hclust, and I've hit a dead end finding a
solution to that error.  I'm not sure whether comm.phylo.cor will do what I
want even if it works.

I wrote a loop to prune the phylogeny separately for each group of species,
which can then theoretically be used to get the distances with
cophenetic.phylo.  However, as soon as I start to run cophenetic.phylo
across my list of trees, R starts to hang up and freeze my entire computer
even though my code is set to skip trees for which distance can't be
measured.  One time it managed run a few and gave a memory error (e.g.,
6050235 Tb of memory is not available).  But R freezes even when I try to
run this on an 12 core mac.

Does anyone have any other suggestions for how to get the mean phylogenetic
distance for subsets of species on a tree?  Thanks for any ideas!


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