he genetic information specifies everything about an organism and its potential. Genotype
specifies possible phenotypes, therefore, phenotypic change follows genetic change. This
obviously should be one of the areas where evolutionary change is seen, and genetic change is
truly the most important for understanding evolutionary processes.
Extremely extensive genetic change has been observed, both in the lab and in the wild. We have
seen genomes irreversibly and heritably altered by numerous phenomena, including gene flow,
random genetic drift, natural selection, and mutation. Observed mutations have occurred by
mobile introns, gene duplications, recombination, transpositions, retroviral insertions (horizontal
gene transfer), base substitutions, base deletions, base insertions, and chromosomal
rearrangements. Chromosomal rearrangements include genome duplication (e.g. polyploidy),
unequal crossing over, inversions, translocations, fissions, fusions, chromosome duplications and
chromosome deletions (
, pp. 267-271, 283-294).
Once the genetic material was elucidated, it was obvious that for macroevolution to proceed vast
amounts of change was necessary in the genetic material. If the general observation of geneticists