[Taxacom] Fwd: Woodpeckers, primates, as well as the Wallace Line gauntlet

[Jason Mate]

Dear Michael,

my reply was aimed, specifically, at these sentences in you previous post:

 Using chance (dispersal) to explain a pattern is just nihilism and leads
> > nowhere.

I
> > can't see the concept of chance dispersal lasting much longer. Once it's
> > dropped, a real science of biogeography may develop. 

Chance dispersal and ecological dispersal are not as different as you may think. If an island is in the Pacific it is logical to suppose that the sources of possible immigrants will be from nearby pacific islands/biotas and also from taxa that, from one reason or another, are better adapted to island life or preadapted (by chance) to their next port of call. But it is still chance. Many are called but only a few are chosen. Why? Some taxa are indeed brilliant at dispersing (coconuts) whereas others aren´t (Coco d´mer) but some truly horrendous dispersers have indeed made it. Thus although you could hypothesize that terrestrial biota in Pacific islands will probably originate from nearby islands and mostly by taxa that are good colonizers (I guess it is this explanatory power that you think is important), you will never be able to say of each taxon that it has indeed originated in this way unless you gather your data (phylogeny, distribution, fossils or remains, etc) and analyze it. If the closest groups to your ingroup happen to come from a mainland source or from a distant source then you can´t say much other than what the data suggests. You could argue for disappeared islands as the sources or stepping stones but this is an ad hoc argument and much more complicated than allowing for chance. Also keep in mind that ad hoc explanations can play both ways.

Best

Jason