[Taxacom] On panbiogeography

[robinwbruce at aol.com]

It is unfortunate, but seems unavoidable for the present, that any discussion of panbiogeography reduces to the antithesis  - vicariance or dispersal - rather than to the coupling of dispersal and vicariance as different phases of the one reality. Croizat's use of the terms [relative] mobilism and [relative] immobilism seem to me to have a precision in English which only a non-native speaker could achieve with neologisms - left to our own devices we would have come up with an acronym!  Croizat's thought seems to be rooted in the idea of the continuity of streams of life across the face of the globe coupled with morphogenetic creativity - from his early and naive 'cloud' distributions figured in 'Manual of Phytogeography', he developed his track analysis in his later works. By so doing, to my mind, he got behind the problem of the tyranny of the  language of modern geography - to discuss past geographies in the terms of present geography is just to embrace fallacy. Thus he circumvented the problem of the present dictating the terms of discussion about the past. Nelson, after I believe much reflection, noted  'What is clear is that Croizat had a unique perception of the possible imprint left by past events on the geography of life today'. To my reading, Michael Heads follows in this tradition.

E. S. Russell, in 'Form and Function', noted that in the history of biology there were only really two ways of looking at life that had arisen in western thought - preformation and epigenesis - material and organismal continuity and novel generativeness. Perhaps viewing panbiogeography in the light of both of these ways of looking at life might be instructive.

Robin