From the New Scientist article:

"Microbes swap genetic material so promiscuously it can be hard to tell one type from another, but animals regularly crossbreed too - as do plants - and the offspring can be fertile. According to some estimates, 10 per cent of animals regularly form hybrids by breeding with other species.

"Last year, scientists at the University of Texas at Arlington found a strange chunk of DNA in the genetic make-up of eight animals, including the mouse, rat and the African clawed frog. The same chunk is missing from chickens, elephants and humans, suggesting it must have become wedged into the genomes of some animals by crossbreeding."

Ha!

What can happen between microbes, and what can happen between vertebrates are very different things. And what is entirely missing from this article is the microbe-mediated shuffling of DNA that goes on -- microbe (viral phage or bacterial) DNA can be inserted in the genome of the species infected, and similarly DNA can be copied out and transferred via the microbe's genome.

Certainly, things are much more complex than anyone knew...

~ Becky in Tucson