Dear R-sid-phylo list,
I am having some problems to interpret the results of a co-evolution analysis
and I hope you can help me to get my head around things.
I have two variables that each show significant non-random phylogenetic signal
(K and lambda) and appear to be significantly correlated in a non-phylogenetic
regression; but when I am performing a pGLS in caper, the lambda is estimated
to be zero and the two variables shows the exact same R-square and level of
significance as estimated from the non-phylogenetic regression analysis. I also
have two other sets of variables that show lambdas >0 (very similar values
from caper and ape) in the pGLS analysis, but for these variables, the R-square
values are smaller from pGLS than those estimated from non-phylogenetic
regression. I guess my question is if I can safely interpret that, in the first
case, phylogenetic history does not significantly affect my trait correlations
(indicated by lambda=0 and very similar simple linear regression and pGLS
results) and in the latter case (i.e. smaller R-squares after correcting for
phylogeny), non-phylogenetic regressions slightly overesti!
mates the correlations of the traits.
Many thanks for the help!
Cheers,
Rizwana
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