Acarina, pycnogonids, Permian ticks?

John R. Grehan jrg13 at PSU.EDU
Wed Apr 18 11:46:42 CDT 2001

>   But I was a
>little shocked in your post last night by the comparison with creationists
>and the ark (I think criticism ceases to be constructive if carried too
>far).  I share your concerns, but that seemed overly harsh.

 From my perspective the invoking of centers of origin and dispersal events
on nothing more than a presumption is not much better, if at all, to
thinking. Much (perhaps most) of what passes for biogeography is simply
dreadful. This criticism is not simply
a matter of taking a particular approach to biogeography (whether area
panbiogeographic, dispersalist etc), but the lack of rigor in the
designation of
what qualifies as biogeographic evidence and the explicit rendition of what
constitutes empirical evidence and what is read into the 'evidence' from a
theorized position. For me it seems that the basic standards of science for
biogeography are simply missing from the cited tick work.

>      But I must admit Klompen's suggestion that the tick found in New
>Jersey hitched a ride on a seabird from South America seems far-fetched and
>wildly speculative.  Even if that genus originated in South America, it
>could have easily been established in North America long before the Upper
>Cretaceous.  I am obviously speculating too, but I think Klompen has used
>both cladistics and biogeography to inappropriately narrow the field of his

My view is that its all empty speculation. At this point there doesn't seem
to be
anything that I would understand as 'science'. One may 'speculate' for example,
whether the arc landed in Turkey or the Himalayas, without either choice
representing science as such.

The option missing from Klompen's account is the possibility that the ticks
were primitively cosmopolitan with respect to the range of the relevant
taxa. Thus the ancestor
of Carios was throughout its current range rather than origination from a
center of origin within one part of the range. The possibility of a more
restricted origin
may be applicable, but at present there is no analytical foundation for
such an assertion.

John Grehan

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