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Name: Jane D.
Status: Student
Age: 16
Location: N/A
Country: N/A
Date: February 2003


Question:
How can one observe microevolution in brief periods of time?



Replies:
A perfect way is to observe antibiotic resistance in bacteria. In any population there is variation and natural selection acts on those variations.

Since bacteria have such a quick generation time, they appear to accumulate changes faster than other living things. ( They do not necessarily, but they multiply so fast they seem to). So, you can put bacteria on an agar plate and put an antibiotic disk on the surface. The bacteria that are closest to the disk are the most resistant and the bacteria further away are more sensitive. You can keep choosing the bacteria closest to the disk over successive generations and they size of the clear zone around the bacteria should decrease over generations.

This shows that when the most resistant bacteria are chosen, more of their offspring make it to the next generation and then more are resistant and they reproduce and more are resistant and so on. Of course this depends on the trait being in the population in the first place. Unless a random mutation occurs, which is rare, the trait has to be present to be acted upon by natural selection.

vanhoeck



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