ABSTRACT
The controversy emerged from the observation of electrophoretic variation. Electrophoresis was a breakthrough in the search for genetic variation in populations, but there were difficulties in its interpretation. Two conceptual models of the structure of the individual genome were offered, and historically affected evolutionary thought. The first, ‘typological’ concept, assumed that a diploid individual is homozygous at all sites except very few mutant heterozygous loci. The second model – called the neo-Darwinian model – assumed that most loci in an individual are in the heterozygous state – and only rarely homozygous. Homologous proteins fulfil the same function in different organisms, and are similar in their molecular structure. They are probably descended from a single ancestral protein. The amino-acid sequences of many proteins are stored in data banks. The rate of accumulation of substitutions appeared to be constant for each protein, and variable among proteins, regardless of generation time.
