� Copyright 1993-2008 by Ziheng Yang The software package is provided "as is" without warranty of any kind. In no event shall the author or his employer be held responsible for any damage resulting from the use of this software, including but not limited to the frustration that you may experience in using the package. The program package, including source codes, example data sets, executables, and this documentation, is distributed free of charge for academic use only. Permission is granted to copy and use programs in the package provided no fee is charged for it and provided that this copyright notice is not removed. Suggested citations: Yang, Z. 1997. PAML: a program package for phylogenetic analysis by maximum likelihood. Computer Applications in BioSciences 13:555-556. Yang, Z. 2007. PAML 4: a program package for phylogenetic analysis by maximum likelihood. Molecular Biology and Evolution 24: 1586-1591 (http://abacus.gene.ucl.ac.uk/software/paml.html). Recent changes and bug fixes are documented in the file doc/pamlHistory.txt. The author can be reached at the following address. However, emails are not welcome: please post your questions and comments at the PAML discussion site: http://gsf.gc.ucdavis.edu/. Ziheng Yang Department of Biology University College London Gower Street London WC1E 6BT England Fax: +44 (20) 7679 7096