When you change the environment of a species, you’ve changed the selection pressure of that species and evolution is going to do its thing. That’s the issue discussed in a post by Olivia Judson at the NY Times Opinionator blog:
In short, the pressures of daily life have been transformed — and
traits that were an advantage Out There may no longer be so Inside.
Similarly, traits that would have killed you in the wild may help you
get along inside a bottle.
Mice show a host of changes, too. Compared to their wild
relations, laboratory mice are typically bigger, more docile, reach
sexual maturity earlier and die younger. Some of these changes can
appear quickly: one study found that the ability to reproduce later in
life declined within 10 generations of the mice being bred in the
Intriguingly, laboratory mice also have longer telomeres than wild
mice. (Telomeres are the segments of DNA at the ends of chromosomes;
they are thought to play a role in aging and cancer.) Since no one is
deliberately breeding mice for extra-long telomeres, this must arise as
some consequence of laboratory life. But what?