After some googling around, I've not been able to find a good reference for the phylogenetic history of the different mouse model strains. So, I've been told that BL6 and A/J both come from a cross between Mus musculus musculus and Mus musculus domesticus and they were independently derived after that common cross.
Does anybody know where I could find out more about the origin of these and other mouse strains?
Oh, I love that chart. I was a post-doc at Jax when that was underway and was totally fascinated. But also--there is an online book that they have on the Origins of Inbred mice: http://www.informatics.jax.org/morsebook/ Might have some interesting additional historical framework.