Review how inherited germ-line mutations add new alleles, then how meiosis and random fertilisation reshuffle existing alleles into new combinations.
Variation in genetically inherited characteristics is the basis for evolution.
Explain how genetic variation between the individuals in a species can be generated.
a. mutation (in genes/DNA generates variation)
b. base substitution / change to base sequence of gene / makes single nucleotide polymorphisms /SNPs
c. new alleles formed / different alleles of gene / multiple alleles
d. radiation/mutagenic chemicals/mutagens cause/increase the chance of mutation
e. meiosis (generates variation)
f. recombination/new combinations of genes/alleles produced by crossing over
g. independent assortment/random orientation of (pairs of homologous) chromosomes/bivalents
h. gametes/chromosomes/DNA/genes from two parents combined (in sexual reproduction)
i. random fertilization (increases genetic variation)
j. in reproductively/geographically isolated populations natural selection may differ
k. in small/isolated populations gene pools change/evolution occurs due to natural selection/genetic drift
I. disruptive selection can cause different varieties/variants/types/phenotypes to diverge
transfer of genes (between bacteria) in plasmids