It is well known that is a positive relationship between tree tips number (tree size) and Ornstein–Uhlenbeck (OU) model support. As a result the OU is almost always selected as the winner model.
So, Why adding tips to a phylogeny increases Ornstein–Uhlenbeck models fit support?
I have read Revell et al. (2008), Harmon et al. 2010, Staler et al. (2012) and Pennell et al. (2015), but I can not understand why.
Also, How this can be fixed?
Thanks in advance!!!!
I don't know the answer, but I found a paper that might help. Attached.
Hi Brian and Cristian
Thanks for your suggested literature and comments.
Sorry for my delayed response but I was reading about, and finally I have a satisfactory answer.
In general, no matter if you add tips at genus or any other taxonomic range Ornstein–Uhlenbeck model will increase its fit. The reason is "because OU can accommodate more variance towards the tips" (Cooper et al. 2016 MEE). In other words, "OU its like a sponge that absorbs the variance/noise in data" (Pennell pers. com.). Thus, adding tips to your tree will increase OU support because this model can deal better with variance (fuelled by more tips) than other models.
Thanks again.
Francisco