The importance of time/space in diagnosing the causality of phylogenetic events: Towards a "chronobiogeographical" paradigm?

A shift from a traditional biogeographical paradigm in cladistic biogeograp hy to a chronobiogeographical paradigm is proposed. The chronobiogeographic al paradigm aims to utilize temporal data in conjunction with spatial data in the detection of discrete historical events, such as vicariance and vica riant speciation, in cladograms. The concepts of primary and secondary cong ruency are introduced in relation to the distinction between repeated area relationships (primary congruency) and common extrinsic causality (secondar y congruency). Simple hypothetical examples demonstrate that area cladogram s cannot be safely interpreted purely as representing the sequence of area fragmentation; rather, they reflect recency of biotic interaction. Temporal data are shown to have a direct and potentially profound influence on the results of traditional cladistic biogeographical analyses, indicating the n ecessity of developing a chronobiogeographical approach. The implementation of the paradigm is considered first from a theoretical viewpoint and then in the context of the type of empirical data usually available. An as yet u ndevised "time/space algorithm" is deemed necessary for the latter, and gui delines are presented for the development of such an algorithm. Finally, we argue that the most rigorous and philosophically justified approach to the detection of phylogenetic causal events can be found only when temporal an d spatial data are considered simultaneously. Consequently, the chronobioge ographical paradigm is seen as a logical elaboration of, not a replacement for, the biogeographical paradigm.