[R-sig-phylo] Negative transition rates in diversitree

Hi all I am fitting multitrait MuSSE models in the diversitree package to study correlated evolution between binary variables and some transition rates (qij) are negative. What is the meaning of negative transition rates? Thanks in advance Miguel Verdú --

[R-sig-phylo] Simulating tree from a given tree

Hi list: Is there any function to simulate a tree from a given tree?. For example, I have a tree encompassing 10 Million years and I would like to simulate the "growth" of such tree for the following 5 MY. Thanks in advance Miguel Verdú --