Hi all, We're doing an analysis of horn evolution in female ungulates where some taxa (30+ species) lack horns entirely and others have horns of varying lengths, so it is a mixture of a discrete and continuous variable.
We want to run a phylogenetic analysis on our dataset, and many have suggested run a "two part" model or "hurdle" model since we have a zero inflation within our continuous data. We have attempted the "hurdle" function using the "pscl" package, but consistently receive this error message: Error in hurdle(log10Hornmm ~ LogSHexp..mm., data = HabPrac) : invalid dependent variable, non-integer values Is it possible to run a phylogenetic analysis using a hurdle model or are there other recommendations for dedicated phylo models? We have attached a plot of our data. We don't want to degrade it into a discrete 0/1 trait, as we already tested it this way in a previous paper. We really would like to capture the continuous nature of the horn length in those species that have it, while still accounting for the many species lacking horns distributed throughout the tree (there are several independent evolutionary origins of female horns). Apologies if we've just missed an obvious phylo model that's commonly used. Thanks! Dr. Ted Stankowich Associate Professor Associate Chair Department of Biological Sciences California State University Long Beach www.csulb.edu/mammallab<http://www.csulb.edu/mammallab> [cid:image001.png@01D79849.898888A0] Thanks, Ted Stankowich
FemaleBovid Plot 1.pdf
Description: FemaleBovid Plot 1.pdf
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