treeducken is my phylogenetic simulation package with the primary purpose of simulating host and symbiont phylogenies simultaneously using the machinery of birth-death models. This extends work on simulating cophylogenetic systems by allowing for scenarios where speciation in the host does not always imply speciation in the symbiont (Keller-Schmidt et al. 2011). This simulation also accounts for extinction in its simulation of host-symbiont systems. treeducken also can simulate under the three-tree model in a manner similar to that used in the SimPhy program (Mallo et al. 2016). See Publications for the paper on treeducken. I am the main contributor and maintainer for treeducken.