Dear Rodrigo, Four species is too few to be able to tell with any confidence whether a statistical model fitted with a star phylogeny or a hierarchical phylogeny better fits your data. However, you can certainly analyze your data with both conventional and phylogenetic methods (e.g., independent contrasts, simulations). If the main result is similar with both approaches, then you have your answer. If not, then ...
With that small a sample size, I would not bother with approaches that transform the branch lengths. Here are two papers that present simulations related to sample size: Blomberg, S. P., Garland, Jr., T. and Ives, A. R. (2003). Testing for phylogenetic signal in comparative data: behavioral traits are more labile. Evolution 57, 717–745. Freckleton, R. P., Harvey, P. H. and Pagel, M. (2002). Phylogenetic analysis and comparative data: a test and review of evidence. The American Naturalist 160, 712–726. Cheers, Ted Theodore Garland, Jr., Professor Department of Biology University of California, Riverside Riverside, CA 92521 Office Phone: (951) 827-3524 Facsimile: (951) 827-4286 (not confidential) Email: tgarl...@ucr.edu http://www.biology.ucr.edu/people/faculty/Garland.html http://scholar.google.com/citations?hl=en&user=iSSbrhwAAAAJ Director, UCR Institute for the Development of Educational Applications Editor in Chief, Physiological and Biochemical Zoology Fail Lab: Episode One http://testtube.com/faillab/zoochosis-episode-one-evolution http://www.youtube.com/watch?v=c0msBWyTzU0 ________________________________________ From: R-sig-phylo [r-sig-phylo-boun...@r-project.org] on behalf of Rodrigo Gavira [rodgav...@gmail.com] Sent: Sunday, July 10, 2016 12:38 PM To: r-sig-phylo@r-project.org Subject: [R-sig-phylo] data anlysis Dear guys, my name is Rodrigo, I am a PhD student from São Paulo State University, Brazil. I am finishing my thesis but have some doubts about how to analyze my data, so I decided contact you. Here I am working on comparative physiology of ectothermic vertebrates. In summary, I work with 4 pitvipers species (*Bothrops* and *Crotalus* genus) in which I measured: Metabolism, water loss by evaporation, and thermal preference and tolerance. Now I would like to compare these results among species. However, as I said, I have only four species to compare. From what I understand when looking at mailing linst archives, this number of taxa are not enough to test the effects of phylogeny on my results, and I must use conventional analyzes. Is that right? If so, please, could you send me some papers dealing with this? Many thanks, guys. Cheers, ------------------------------ MSc. Rodrigo Samuel Bueno Gavira Biologist - PhD student in Zoology Universidade Estadual Paulista - UNESP Department of Zoology Rio Claro - SP - BRAZIL [[alternative HTML version deleted]] _______________________________________________ R-sig-phylo mailing list - R-sig-phylo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-phylo Searchable archive at http://www.mail-archive.com/r-sig-phylo@r-project.org/ _______________________________________________ R-sig-phylo mailing list - R-sig-phylo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-phylo Searchable archive at http://www.mail-archive.com/r-sig-phylo@r-project.org/