science, evolution in D&G

Can someone with a background in science weigh in on the claims D&G make about biology and evolution supporting their rhizome theories? This is a last minute grab to insert science into today's in class discussion agenda...

I thought their treatment of DNA in TP was intriguing, but could have gone much farther as both a problematic and fruitful example. At the same time that DNA is arborescent, that it codes, predicts, and is the most basic instantiation of genealogy, it also retains significant rhizomatic tendencies: its ability to mutate, to recombine. I'm thinking especially of viruses here, and the ways in which they can snip out a DNA fragment, duplicate it, and incorporate it into their own structure.

D&G talk about this on page 10 of TP:

"the aparallel evolution of two beings that have absolutely nothing to do with each other." More generally, evolutionary schemas may be forced to abandon the old model of the tree and descent. Under certain conditions, a virus can connect to germ cells and transmit itself as the cellular gene of a complex species; moreover, it can take flight, move into the cells of an entirely different species, but not without bringing with it "genetic information" from the first host (for example, Benveniste and Todaro's current research on a type C virus, with its double connection to baboon DNA and the DNA of certain domestic cats). Evolutionary schemas would no longer follow models of arborescent descent going from the least to the most differentiated, but instead a rhizome operating immediately in the heterogeneous and jumping from one already differentiated line to another. Once again, there is aparallel evolution, of the baboon and the cat; it is obvious that they are not models or copies of the other (a becoming-baboon in the cat does not mean the cat "plays" baboon). We form a rhizome with our viruses, or rather our viruses cause us to form a rhizome with other animals."

I take little issue with their questioning of inheritance and linearity on the viral level, I think in this microscopic arena the horizontal possibilities for evolution and borrowing are real and probably rhizomatic. I don't think the same trends bear out over the larger course of evolution, which is absolutely contingent upon the ability to pass down traits, arborescently. Granted, the traits-to-be-passed may result from a freak genetic mutation, but I'm not sure that this is relevant. It seems to me that using recent viral theories to support a rhizomatic relationship with animals is a bit of a stretch, and does not change the naturally, necessarily arborescent patterns that have delivered us (us being: everything) here in the first place.