[Taxacom] Ratites and frogs of New Zealand

[John Grehan]

Ken,

I guess I misinterpreted your earlier statement "If you haven't yet
abandoned that Trans-Pacific track for primitive frogs, you should do so
immediately." as trying to end their Pacific affinities. I was simply
pointing out the Pacific affinities (and therefore trans-Pacific track")
are still evident.

It is not a matter of Pacific affinities not being "all that
surprising". They are indeed trite. The problem is that they are widely
regarded as uninformative about earth history because they do not
conform to the expectations of certain geohistorical models and
molecular clock theorized ages so long-distance chance dispersal has to
be invoked.

Of course various frogs are found outside the Pacific, including the
basal lineages. But there are distinct patterns that suggest the
ancestors of certain frog groups were centered on different
geohistorical areas that are reflected in the ranges of their
descendants. Some groups with a Pacific baseline also have outliers in
or near Madagascar which is proximate to one of the most important
global biogeographic centers of evolution (The African Gate). 

I've not studies the dispersal (translation in space + form-making) of
the Triadobatrachidae of Madagascar. What is of biogeographic interest
is the geographic distribution of its nearest relatives outside
Madagascar. I'm not up with all the finer points of frog taxonly, but
Pough et al (1998) suggested that the Sooglosidae of the Sychelles are
most closely related to the Australian Myobatrichidae rather than to
anything in Africa. 

With respect to conclusions about New Zealand - yes the biogeographic
patterns are concordant with much of the biota being the result of
"vicariance" (although not necessarily through the separation of NZ from
Gondwana). It really does not matter whether this impresses you or
anyone else. What is impressive to me is what people produce in the way
of evidence for their views either way. As for increasing scrutiny,
there has been little as the molecular systematists have just invoked
their molecular clock as maximal divergence estimates when they are
really minimal, and just ignored any evidence (such as spatial
structure) to the contrary. They also ignore vicariism as in the
Metrosideros case.

Like all things, the proof in the pudding is in the eating. What is
digestible to one is indigestible to another. That's normal for science.
You are welcome to your views. But views themselves are of no account.
The application of empirical methodology is what counts in science -
whether for or against any particular biogeographic model. So if you
come up with analysis of actual distributions to support your
contentions about "semantic bickering and obfuscatory verbiage" I will
indeed be very interested.

John Grehan



> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-
> bounces at mailman.nhm.ku.edu] On Behalf Of Ken Kinman
> Sent: Thursday, January 11, 2007 11:19 PM
> To: biogeography at bohm.snv.jussieu.fr
> Cc: taxacom at mailman.nhm.ku.edu
> Subject: Re: [Taxacom] Ratites and frogs of New Zealand
> 
> John Grehan wrote:
>      As I went back over the frog question I recalled that indeed the
> sister-group relationship between the NZ frog and Ascaphus of W North
> America was not supported.  However, this does not end the Pacific
> affinities of the NZ Frog....    So I would conclude at this time that
a
> Pacific baseline for the NZ frogs still stands among at least some
> phylogenetic reconstructions as part of an assemblage of the most
basal
> frog
> lineages. This might imply that the frog ancestor was distributed over
> landscapes involving the Pacific as well as Atlantic and Indian Ocean
> regions before they were the oceans of today), but the primitive
lineages
> differentiated over the Pacific sector while other parts of the world
> encompassed the more derived lineages.
> *******************************
> John,
>      Is ANYONE trying to "end the Pacific affinities of the NZ Frog"?
> Certainly not me, since I would obviously even further restrict it to
the
> southern Pacific.  The verbiage of your whole post seems to be stating
the
> obvious in a rather roundabout and bloated sort of way.  New Zealand
is on
> the edge of the Pacific rim, so its Pacific affinities are not at all
> surprising.
> 
>      As for your conclusions, I would agree the primitive lineages of
the
> CROWN group certainly seem to center on the Pacific basin----again
stating
> the obvious.  However, stem group frogs (outside of the crown group)
are
> found outside the Pacific basin (e.g., Triadobatrachidae of
Madagascar).
> Frogs could have originated just about anywhere before the continents
> started drifting apart.
> 
>      Panbiogeography (particularly your application of it) doesn't
impress
> me in the least.  In particular, it seems to lead to the conclusion
(at
> least your interpretations of it) that New Zealand's faunae are
largely
> the
> result of vicariance, and this is thankfully coming under increasing
> scrutiny.  Broadly speaking, I see panbiogeography as too restrictive
and
> often misleading (just as I see strict cladism as restrictive and
often
> misleading).  Both are too legalistic and full of self-congratulatory
> verbiage for my tastes.  I think I'll stick to a modern form of
Darwinism
> and a more eclectic approach to both taxonomy and biogeography.
Biology
> is
> already too burdened by semantic bickering and obfuscatory verbiage!!!
>     ----Ken Kinman
> 
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