Hi Russel,
What you see is the large uncertainty in “ancestral” states, which is part of
the intercept here. The linear relationship that you overlaid on top of your
data is the relationship predicted at the root of the tree (as if such a thing
existed!). There is a lot of uncertainty about
All true. I would just add two things. First, always graph your data and
do ordinary OLS analyses as a reality check.
Second, I think this is the original paper for phylogenetic prediction:
Garland, Jr., T., and A. R. Ives. 2000. Using the past to predict the
present: confidence intervals for
The other possible null model would be a "star" phylogeny with no
hierarchical structure, equal-length branches, and also Brownian motion.
But that's generally viewed as outside of the range of reasonable
possibilities.
Cheers,
Ted
On Tue, Jun 29, 2021 at 12:05 PM Nathan Upham wrote:
> Hi
Hi all, Russell, Nate,
I took an interest with some of the commentary here, so here's my two cents.
> I was surprised that AIC would vary this much in a dataset where the trait
> data, number of tips, and branching
> topology used to compute the model are more or less constant between trees.
I
Hi Russell and all, sounds good.
I’d suggest that the “null model” for fitting trait data to a phylogeny should
be single-rate Brownian motion, i.e., you’re assuming that given data on the
ancestor-to-descendant relationships of the species (and timing of
divergences), and assuming the trait
