Hi all, I’m calculating lambda (as a measure of phylogenetic signal) for a dataset of bird plumage color traits across a clade of ~400 species. However, for a few of the traits, the lambda estimate is 1.000000. This happens both with phytools::phylosginal and with geiger::fitContinuous(model=‘lambda’), although for a couple additional traits in phytools.
I realize that these implementations set a hard upper bound of 1 for lambda, so the “real” lambda for these traits may actually be higher than 1. I also realize that lambda>1 can be interpreted as meaning that close relatives are more similar to each other than expected under BM. But when I look at the trait values, and especially based on my familiarity with the taxa in this tree, that interpretation doesn’t feel right to me. The traits don't look particularly conserved. I also wonder if measurement error could be playing a role in this, since it is fairly high in this dataset, and when I run the analyses without measurement error, I don’t get lambdas of 1 anymore (although still in the 0.9 range). I also calculated Blomberg’s K and didn’t get values near 1 for any traits. And there doesn’t seem to be an obvious correlation between values of K and lambda for each trait. Hopefully someone may be able to illuminate my with a guess as to what might be happening here. Thank you all very much, *--* *Rafael Sobral Marcondes* PhD Candidate (Systematics, Ecology and Evolution/Ornithology) Museum of Natural Science <http://sites01.lsu.edu/wp/mns/> Louisiana State University 119 Foster Hall Baton Rouge, LA 70803, USA Twitter: @rafmarcondes <https://twitter.com/rafmarcondes> [[alternative HTML version deleted]] _______________________________________________ R-sig-phylo mailing list - Rfirstname.lastname@example.org https://stat.ethz.ch/mailman/listinfo/r-sig-phylo Searchable archive at http://email@example.com/