Evolution witnessed (for the nth time) on lizards
We witness evolution every day we get an infection or the flu — microorganisms change constantly, which gives their offspring the ability to defeat antibiotics and immune system defenses. Doctors have known this for decades now. But what would you say if lizards from one species change into another, different species altogether?
This is exactly what has happened. At Pharyngula, a nice story about thirty years of evolution shows what Darwin might have seen:
Here’s the story: in 1971, scientists started an experiment. They took 5 male lizards and 5 female lizards of the species Podarcis sicula from a tiny Adriatic island called Pod Kopiste, 0.09km2, and they placed them on an even tinier island, Pod Mrcaru, 0.03km2, which was also inhabited by another lizard species, Podarcis melisellensis. Then a war broke out, the Croatian War of Independence, which went on and on and meant the little islands were completely neglected for 36 years, and nature took its course. When scientists finally returned to the island and looked around, they discovered that something very interesting had happened.
Oh, let’s not spoil the ending of the story — read it yourself.
April 23rd, 2008 at 17:29
Just a correction. Microorganisms DO NOT change to defeat antibiotics. They mutate (some for their own good, some for worse) and the strain which is able to survive the antibiotics prevails and keep on their reproduction/infection cycle.
This point is key.
April 23rd, 2008 at 17:31
I didn’t mean that they mutated with the express purpose to defeat antibiotics. Purpose necessarily requires sentient intelligence, and microbes aren’t sentient or intelligent.
I just meant to say that microbes happen to mutate and those mutations confer some of their descendants the ability to succeed. This doesn’t require purpose at all. It’s us who insist on seeing the relationship and misguidedly inferring purpose where there is none.
Thanks for the clarification.
April 23rd, 2008 at 17:38
Exactly, this is the key element about evolution which is usually completely misunderstood.