Here's why this matters.
Complexity evolves mainly through duplications and mutations in structural and control genes.
Genes can mutate or remain stable, migrate laterally from species to species, spread through a population by mechanisms whose operation is not fully understand, evolve coordinately, splice, stay silent, and exist as pseudogenes. This liberal spread of rules, each of which can be observed in use by scientists, does not just sound facetious but also, in our opinion, robs monophyletic molecular evolution of its vulnerability to disproof, and thereby of its entitlement to the status of a scientific theory. Tim Ikeda and I have correspondended a bit about this. But what I really want to know, re this post, is what experimental literature exists on lateral transfer. I'm guessing not much.