Feb. 19, 2013 Species facing widespread and rapid environmental
changes can sometimes evolve quickly enough to dodge the
extinction bullet. Populations of disease-causing bacteria
evolve, for example, as doctors flood their "environment," the
human body, with antibiotics. Insects, animals and plants can
make evolutionary adaptations in response to pesticides, heavy
metals and overfishing. Previous studies have shown that the
more gradual the change, the better the chances for
"evolutionary rescue" -- the process of mutations occurring fast
enough to allow a population to avoid extinction in changing
environments. One obvious reason is that more individuals remain
alive when change is gradual or moderate, meaning there are more
opportunities for a winning mutation to emerge. Now University
of Washington biologists using populations of microorganisms
have shed light for the first time on a second reason. They
found that the mutation that wins the race in the harshest
environment is often dependent on a "relay t