Re: A question about genetic splicing

Dear Shawn,

Thank you for your question (which is a tricky one). However, we first need 
to straighten out a little discrepancy between the subject and the body of
your question:
Your subject is directed to (genetic) splicing (or alternative splicing)
which is a process eukaryotes use to generate different mRNA molecules from
a single pre-mRNA molecule. You may know that in order to translate genes
(which are located on the chromosomes and consisting of DNA) into proteins
the DNA is first transcribed into an RNA molecule which is consequently
translated into the corresponding amino acid sequence (i.e. a protein) by
the ribosomes. The ribosomes need a "specialized" form of RNA, called mRNA
(m is for 'messenger'). However, a simple transcript of the DNA won't
produce the proper mRNA that can be utilized by the ribosomes - instead
this (so called)  pre-mRNA which mainly consists of introns (regions not
coding for amino acids) and exons (regions coding for amino acids) needs to
be processed (for example a CAP structure is added and the introns are
spliced out). During this process also alternative splicing may occur that
you can imagine of combining different exons to build up a second (or third
etc) protein from the same DNA sequence. Thus, alternative splicing is a
way to produce more than just a single protein from a given stretch of DNA
sequence.

Genetic alterations, on the other hand, usually refer to mutations, i.e.
changes in the DNA (which also might lead to different splicing). Such
mutations occur all the time and randomly. New species evolve by such
mutations of the DNA sequence. This means that if you were to go back in
time you would (a couple of thousand years ago) find a common ancestor to,
for example, humans and apes. This creature would have a set of genes
(called the "genome") that is similar to the genome of both today's humans
and apes. Now, how did two species (more or less distinct) like humans and
apes evolve from the same ancestor? The basic concept to this is mutations
and subsequent selection. In other words, some of the genes in the ancient
creature were mutated (mutation) and only a very few of these mutations
turned out to be beneficial for the survival of the resulting "new"
creature and in turn were conserved within the genome and consequently
passed on to its offspring (selection). At this time point the ancestry
forks, i.e. you have the "old" genome and the "new" one that contains the
mutation(s). 
If you repeat this whole process (called evolution) a couple of times you
will eventually end up with two (or more) distinct "species". However, and
that's where your question becomes really tricky: there is no clear
definition in science of what a "species" actually is, i.e. to which
degree the genomes of the two compared beings need to diverge in order to
call them separate species. So while most people agree that, for example,
aligators and crows (which share a common ancestor) are distinct species
such a distinction is not always clear for any two beings. 

Anyways, and back to your initial question, as you see: mutations occur
constantly and all over the place and thus new genomes ARE in fact created
as we speak (or write in this case). It is only a matter of time until
these genomes have diverged enough until the beings harboring these altered
genomes are recognized as new species. Since these processes take a lot of
time we usually don't live long enough to observe the natural creation of a
new species. However, if we speed up this process of evolution in the lab
by controlled mutations of the genome or insertion of new genes (which is
already being done for a variety of animals, e.g. in mice, or in yeast) you
might speak of new species that are created, depending on the definition
you use to define what a "species" is. 
   
Hope that helps,

Erik