Question

How do mutations increase the genetic variation within a species?

Answer 1

They are errors in genes that might not normally be in the gene pool. Therefore adding an alternative gene...the gene could possibly be beneficial to a population

Answer 2

A mutation may begin as a permanent change in the linear nucleotide sequence of DNA as DNA polymerase III neglects to correct the error during proofreading.

On a molecular scale, these permanent changes may be a point mutation, i.e. a single nucleotide is substited for another. Since ribosomes reads nucleotides in triplets (i.e. codon), a nucleotide substition might spell out a different amino acid, which then will translate into an abnormal protein overall; or the substitution results in the production of one of the three stop codons, which then will halt amino acid sequence production and therefore no protein will be translated afterward.

Alternatively, the mutation could be an insertion, i.e. a single or few nucleotide(s) are added. It could also be a deletion where a single or few nucleotide(s) are eliminated. Both of these types may alter codons, hence altering amino acids translated and therefore proteins, as they both may potentially shift open reading frames (ORF).

Note: Only when either three micro-scale mutations occur on a genetic open reading frame (ORF) will a significant evolutionary mutation occur.

To answer your question: Permanent changes in linear nucleotide sequences will lead to an altered translation of proteins if a) the change altered a codon, b) a ribosome translated an amino acid different from the intended, and c) tRNA constructed a peptide sequence which led to an abnormal protein, be it operational or otherwise, and these abnormal proteins cause (as presumed) a significant, or at least notable, phenotypic alteration thereby evolving your particular species.

Answer 3

@Cardinal_Carlo Not true and incorrectly worded-"Only when either three micro-scale mutations occur on a genetic open reading frame (ORF) will a significant evolutionary mutation occur."

Although rare, the are instances that a single point mutation can result in a different amino acid. This in turn can lead to increased or decreased protein/enzyme efficiency it the amino acid that changes in in the active site or the protein/enzyme.

Also, it is misleading to say "...significant evolutionary mutation occur." You are using significant to mean "has fitness effect". All mutations are equally significant—their effects, however, are not.