It is difficult to believe that any of the characters examined by Burdon could be selectively neutral.

From a mathematical standpoint, an unused gene (selectively neutral) has a steadily decreasing probability of retaining potential functionality over time.

The degeneration and complementation processes make the DDC model a selectively neutral mutation process.

Enzyme polymorphisms: Evidence that they are not selectively neutral, 1972, Nature New Biol.

On the hypothesis that polymorphic enzyme alleles are selectively neutral.

However, several other changes subsequently occurred, which were selectively neutral as they did not affect hormone binding.

Warren Ewens, "The sampling theory of selectively neutral alleles", Theoretical Population Biology, volume 3, pages 87-112, 1972.

It was found that the various chromosome types do not fluctuate at random, as they would if selectively neutral, but adjust to certain frequencies at which they become stabilised.

Kimura drew a distinction between molecular evolution, which he saw as dominated by selectively neutral mutations, and phenotypic characters, probably dominated by natural selection rather than drift.

Many ecogenetic situations (such as polymorphism) were not selectively neutral, on the contrary, they were maintained by the force of selection.