Is everything everywhere?

"...For about a century, microbiologists have believed that the organisms they study are unhindered by geographic boundaries, traveling the world and thriving wherever they find their preferred environment--be it hot springs, freshwater ponds, or rotting fir trees. That view gives researchers who study microbes a rather different perspective on the world. As the Dutch biologist Lourens Bass-Becking put it in 1934: "Everything is everywhere; the environment selects."

Or maybe not. In the past few years, many microbial ecologists have come to believe that microbes are not infinitely mobile. Bass-Becking's dictum is really only "an assumption,"says Jessica Green of the University of California, Merced. "It's based on a confusion of hypotheses for facts."..."

I've got a new feature in Science (registration required) looking at microbial giogeography, and whether the patterns seen for plants and animals - such as the fact that bigger islands contain more species than small, or that the life in two blocks of forest becomes more different as the distance between them increases - hold for microbes. Many have thought that they don't, but the recent boom in studies of DNA fished out of the environment suggests that perhaps they do, in some form or other.

The scientists I spoke to: Jessica Green,Bland Finlay, Claire Horner-Devine, Jennifer Hughes, Tom Fenchel.