While we disagree on some theoretical points, it is from W. J. Bock that I learned as a graduate student to appreciate the importance and subtleties of a functional-adaptive perspective in phylogenetics. Our long friendship has been a constant source of inspiration for me. Bock is the foremost living champion of what may be considered a Darwinian approach to the analysis of evolutionary history. Although he continues to refer to this practice of systematics as an evolutionary one (he has in fact brought exceptional new theoretical strength to it), I prefer the Darwinian appellation. Most high- profile evolutionary systematists in the past have not followed rigorously a methodology that is inherent in Darwinian precepts of adaptive evolution.
My thanks to J. Warshaw who prepared the schema on Figure 1. I am also grateful to N. MacLeod, E. Sargis and J. Warshaw, who made many useful stylistic suggestions.