Re: Cloning v. Genetic Variations

Mike,

Before I directly answer your questions, it is important to understand 
precisely what cloning is:  a process by which an exact duplicate of a 
living thing is made.  This means that the parent and offspring have the 
exact same genetic make up.

For your first question (How does genetic variations passed down from 
generation to generation factor into cloning?):  In a cloning situation, 
the offspring will have the same DNA sequence, so the process of 
introducing variation in offspring is stopped.  The genetic variation seen 
in a non-cloning situation is typically a result of mixing genetic 
information (mother + father).  However, in bacteria and other asexually 
reproducing organisms, genetic variation is derived either from mutations 
introduced as the parent’s genome is being copied before cell division 
(vertical evolution) or from external sources such as certain types of 
viruses or small pieces of circular DNA called plasmids that integrate into 
a host’s genome.  (horizontal evolution)

For your next question (How would scientists be able to keep the clone from 
not developing the same exact variations so that the species being cloned 
would actually help the species continue to thrive without the side-effects 
of too much "in-breeding"):  By definition, a clone is an exact duplicate, 
thus changing the genetic make-up to "better" the species would be 
characterized as genetic engineering, not cloning.  Nonetheless, yes, it is 
possible, and common, to engineer a "better" species.  For example, many 
high yield crops in this country are engineered to resist certain pests or 
to grow bigger or with more flavor.  This can be done by either introducing 
a new gene, or removing a gene from the plant’s genome.

Your comparison of cloning to "in-breeding" is not accurate.  "In-breeding" 
means that you are generating offspring (sexually) from two closely related 
animals (i.e. brother and sister).  The problems that can arise from such a 
genetic cross is a result of similar genetic make-up of the two 
individuals.  The closer related the parents are, the more likely they will 
be carrying similar recessive genes which only become a problem when the 
offspring gets two copies of it.  Thus "in-breeding" is fundamentally 
different from cloning because it involves a mixing of genetic material 
whereas cloning is merely making a direct copy of an existing genome 
(animal).  

I hope that answers your questions.  If you need more clarification, feel 
free to email me directly, or post another question!

Brian Cobb