Acarina, pycnogonids, Permian ticks?
kinman at HOTMAIL.COM
Wed Apr 18 10:16:14 CDT 2001
I think Klompen is probably correct that ticks (as a group) mostly
likely had a Gondwanan origin, but narrowing it down to Australia is overly
optimistic given the paucity of Mesozoic data (one tick in New Jersey).
This is compounded by the uncertain time of origin (Permian vs. Jurassic).
As for a South American origin for the genus _Carios_, I would agree
that he seems to be really overextrapolating, and he could be right or
wrong. The data simply isn't there, especially if ticks arose in the
Permian (which to me seems more likely than a Jurassic origin). 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.
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
Only time will tell, but don't be surprised if we eventually find lots
of ticks in the Mesozoic of North America (including more Carios).
>From: John Grehan <jrg13 at PSU.EDU>
>Reply-To: John Grehan <jrg13 at PSU.EDU>
>To: TAXACOM at USOBI.ORG
>Subject: Re: Acarina, pycnogonids, Permian ticks?
>Date: Wed, 18 Apr 2001 07:02:08 -0400
> Therefore I think that there were plenty of ticks in North America
> >>during the Cretaceous, and Klompen's hypothesis that the New Jersey tick
> >>hitched a ride on a seabird from South America is rather far-fetched.
>Far-fetched or not, the hypothesis is not based on any kind of evidence at
>Its just a derivation of the presumption that the means of dispersal of
>alone is the key to their distribution. As far as I can see there is no
>in this kind of biogeography.
>, and on the basis of his published
> >phylogenies, his geographic hypotheses are consistent with the evidence.
>This seems to be circular. From what I have read so far Klompen interprets
>the location of the basal lineage as the center of origin, so naturally the
>distribution is 'consistent' with the 'evidence'. The presumption here is
>that global tick distribuiton can be resolved in terms of an identifiable
>center of origin and means of dispersal, with the location of basal
>being the predictor of the center of origin. This kind of biogeography has
>never been substantiated on an empirical basis (i.e. that the location of
>lineages necessarily denote such centers of origin).
>None of this criticism is new. It interests me that most biogeography that
>continues to be published relies on faith in means of dispersal and centers
>of origin regardless of the lack of science involved. In any other subject
>such approaches could not be published. It seems that systematics managed
>to move beyond the phase of unsubstantiated assertions, but biogeography
>for the most part remains in the 19th century, with the ironic result that
>many systematists set a high standard for the taxonomic work, and a low one
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