Origins of genetic variation

Random mutations are the ultimate source of genetic variation. Mutations are likely to be rare and most mutations are neutral or deleterious, but in some instances, the new alleles can be favored by natural selection. Polyploidy is an example of chromosomal mutation.

Mutations are changes in the DNA. A single mutation can have a large effect.

1) mutation - an alteration in DNA sequence, various types

2) intragenic recombination - results in entirely new associations of genes not present in either parental genome.

Two forms of intragenic recombination:

a) crossing over
b) independent assortment
3) reticulation ? acquisition of genetic material from unrelated or relatively unrelated sources (e.g., hybrid species, horizontal gene transfer).