CODEWITHSUNDEEP
rphylogeny
Ariana7521
Ariana7521

Reputation: 1

No correlation after phylogenetic independent contrast

I am testing the correlation between two physiological parameters in plants. I am a bit stuck on the interpretation of the phylogenetic independent contrast (PIC). Without considering the PIC, I got a significant correlation, but there is no correlation between the PIC. What does the absence of correlation between the PIC mean:

OR,

Upvotes: 0

Views: 154

Answers (1)

teofil
teofil

Reputation: 2384

Looks like you've run into the classic case when an apparent correlation between two traits disappears when you analyze the independent contrasts. This could be due to relatedness: closely related species will tend to have similar trait values and that might look like a correlation between the traits. But it is simply a byproduct of the bifurcating nature of phylogenies and statistical non-idependence of species' trait values. I would recommend to go back to the early papers (1980 and 1990) by Felsenstein, Garland, etc, and the book by Harvey and Pagel (1991) where these concepts feature prominently.

Otherwise, there are many similar threads on the r-sig-phylo mailing list (highly recommended), websites of various phylogenetic workshops (e.g., Bodega, Woods Hole, ...), and blogs (e.g., Liam Revell's phytools blog) that might be of help.

Upvotes: 1

Related Questions