Who said evolution could not happen fast? Has it not been one of the main criticisms from evolution-critics that we cannot observe evolution taking place today? Well, here is just one recent example of evolution over a few generations only.
In case you have not heard this story before, a study published in the March issue of PNAS demonstrated that the Italian wall lizard (Podarcis sicula) had developed gross morphological changes in only a few decades. In particular, the story was that in the early 1970’s the lizard was introduced by humans to the island Pod Mrcaru in Croatia (from the neighboring island called Pod Kopiste).I’ve made a map just to show where that is:
A google map of the region can be found here
Five adult pairs introduced in 1971. During the Croatian war of independence, the lizards were long forgotten, not studied again until decades after their release. At that time, the researchers were not even sure whether there would be any lizards left. Imagine their surprise, then, when they discovered the species now dominates the island in great numbers, well over 10.000!
But as if this was not a big surprise itself, the researchers discovered that the Pod Mrcaru lizards had developed morphological differences, including larger heads, broader jaws and a harder bite. In addition, the lizards had developed a completely new gut structure. Why? Because the two islands differed in what the lizards could feed upon. In a great story about this exciting finding, National Geographics notes:
Pod Mrcaru, for example, had an abundance of plants for the primarily insect-eating lizards to munch on. Physically, however, the lizards were not built to digest a vegetarian diet.
Researchers found that the lizards developed cecal valves—muscles between the large and small intestine—that slowed down food digestion in fermenting chambers, which allowed their bodies to process the vegetation’s cellulose into volatile fatty acids.
“They evolved an expanded gut to allow them to process these leaves,” Irschick said, adding it was something that had not been documented before. “This was a brand-new structure.”
Can anything be more “wow” than this?
So not only did the study demonstrate the ability of only a few number of lizards to survive and thrive in a relatively new habitat. The study also demonstrates just how fast evolutionary preassures can lead to adaptions in a much faster time than what we normally think of.