Add option to only include extant genomes in the 3-node subtree
Add option to only include extant genomes in the 3-node subtree

glennhickey/hal,glennhickey/hal,glennhickey/hal,glennhickey/hal,glennhickey/hal,glennhickey/hal,glennhickey/hal,glennhickey/hal