Evolution of organ systems: Phylogeny, function and reciprocal illumination

Abstract

‘Mainstream’ cladists have formulated a rigorous Popperian methodology of falsifiability and have claimed that pattern in evolutionary biology is logically prior to the reconstruction of process and that cladograms have logical precedence over phylogenetic trees and phylogenetic trees over evolutionary scenarios. It is further claimed that cladograms are more scientific than phylogenetic diagrams and diagrams more so than evolutionary scenarios. Here I argue that evolutionary biology deals — in contrast to physics — with unique events which can be told only in a narrative. There is reciprocal illumination between pattern and process. Eolutionary scenarios, i. e. narratives of cladogenetic, anagenetic, adaptive and biogeographic processes are the ultimate goals of all systematic and evolutionary biology. There is reciprocal illumination between all elements of the evolutionary scenario. The criterion for a reliable scenario is its inner coherence.