Positive Darwinian Selection in Evolution of Protein Inhibitors of Serine Proteinases (original) (raw)

1. M. Laskowski, Jr.,
2. I. Kato,
3. W.J. Kohr,
4. S.J. Park,
5. M. Tashiro, and
6. H.E. Whatley
7. Department of Chemistry, Purdue University, West Lafayette, Indiana 47907

Excerpt

The Neutral Theory of Molecular Evolution by M. Kimura (1983) deservedly stands as a statement of consensus among molecular evolutionists. It asserts that the overwhelming majority of fixations of mutations are selectively neutral. Selection (negative Darwinian selection) relentlessly weeds out the strongly deleterious mutations. Positive Darwinian selection is rare. We agree with this theory, but we note that it deals with what happens most of the time. We believe that a minority of proteins are species specific and frequently exhibit positive Darwinian selection. The purpose of this paper is to present some evidence that protein inhibitors of serine proteinases exhibit in their evolution characteristics associated with positive Darwinian selection. Although the “neutral theory” is now widely believed, there are still many “selectionists” who oppose it. However, the theory is based on or supported by five phenomenological generalizations, which are almost universally believed and which are explicitly or implicitly stated in...