Mutating Without Science Fiction (just the science)

Let's talk mutation! And, no, unfortunately this isn't a discussion on the ins and outs of Gremlins and how they work. It is, however, a bit of an intro to mutation within genetics and how they work within the bigger picture of evolution. Mutation is an aspect of evolution that you may not think about as much. Often, people will talk about how "this individual was more fit and passed on that genetic variation to further generations; this change caused the evolution." Where did that fitness come from though? Animals cannot "decide" that something will help them survive better, but the ability to do so needs to come from somewhere. This is where mutation comes in.

Mutation comes in a number of different forms but, focusing for now on how it plays into Darwin's evolution, in order for fitness to occur there need to be some sort of genetic hiccup within an individuals code that can then be passed on to offspring and subsequent generations. This could be a problem with the DNA polymerase, genetic duplication, chromosomal inversion, etc. In order to be relevant to evolution the change in the individuals DNA needs to not only be able to be passed on, but also cause some sort of change within the individual. For example: synonymous point mutation in the protein coding regions will not have any effect on the individual because the alternate triplet sequence will code for the same protein, presenting the same within the genetic sequence. 

After deciding that 

1) a noticeable change in the genetic sequence has occurred and

2) the genetic sequence can be passed on

we must also determine if the new mutation is positively affecting the fitness of the individual and can therefore increase the fitness of the population as a whole. If the individual has, for example, some sort of genome duplication, there is almost no possibility that the individual can reproduce and they become sterile. If they can, they are now limited to who they can reproduce with (tetraploids with tetraploids, diploids with diploids, etc.). If the mutation is negatively affecting an individuals fitness then, even if it is passed on, it will most likely be detrimental to the population. 

After all of this has been established, evolution can occur (thanks to mutation). As generations continue on, inheriting the new mutation, it is likely they will stack on mutations of their own. These mutations may not be noticeable, increase fitness, or anything of the sort. But, something that already contains mutations to the genetic code is more likely to make a mistake later down the line, especially in the polymerase phase. The rate of mutation is likely to increase as the gene pool becomes more confined and isolated (such as in a bottle-neck event or genetic drift), and decrease when the gene pool is more open and allowed to move and roam (such as with individuals that are highly migratory and can survive in vast, open areas.)

All of this to say...

Dang I want to watch Gremlins again...