I have a phylogeny and two categorical traits (one binary, one multi-state) mapped to its tips. My claim is that there is a correlation in their phylogenetic distribution, i.e. that they evolved in concert, or dependently.

How can I test that formally?

I have tested for phylogenetic signal using Fritz' D (Fritz & Purvis 2010,Article Selectivity in Mammalian Extinction Risk and Threat Types: a...

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of which there is plenty. But I am stumped on how to show that there is a correlation in presence/absence of one trait and the state of another. I can visualise that in a traitgram/phylomorphospace plot in phytools, but that doesn't give me a number that says "these are not independent".

In principle, phylogenetic independent contrasts (Felsenstein 1985) could be used to test for correlation, right? But PIC is for continuous characters, not categorical ones.

I have found phylogenetic logistic regression (Ives & Garland 2010, https://academic.oup.com/sysbio/article/59/1/9/1723322), but this is only for binary traits. I have read the "Analysis of Phylogenetics and Evolution in R" (Paradis 2012) and "Modern Phylogenetic Comparative Methods and Their Application in Evolutionary Biology" (Garamszegi (Ed.) 2014) books and googled myself to perplexion. I hope someone more knowledgeable can help me!

Many thanks in advance.

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