Mutations
The year 1900 was a milestone in our
quest to understand the nature of evolution. A Dutch plant physiologist,
Hugo de Vries, discovered the source of new variation. Working with primroses,
de Vries found radical changes in plants from one generation to another.
He called these changes mutant forms. There was change in the genes and
new variation that had not been apparent earlier.
In this movie you will observe the replication
of a strand of DNA in which a mutation or error in the replication or recoding
process occurs. We will explore mutations more in another segment of this
module. However, it is very important to recognize that mutations may cause
large changes in an organism. In this respect, a mutation can have a great
impact on the physical characteristics of an organism. If nature finds that
change adaptive, then through the process of natural selection the genetic
change probably will be passed on through subsequent generations.
The cow is an excellent example of a
mutation that was adaptive. The duplication of a gene proved to be adaptive
in that it enabled the cow and other animals like it to eat grass. Actually,
the cow eats grass and bacteria eat the grass and the cow gets nutrients
from being able to breakdown the bacteria. A complex story but one that
is based on a mutation - the replication of a gene.
Keep in mind, mutations can be negative
and most are. Mutations can also be neutral to natural selection. In that
case, it may hang around and may or may not ever be useful. Mutations can
also be positive. In this sense, they prove to be adaptive for some reason.
