[Taxacom] Biogeography of Australasia

[John Grehan]

Fred,

I think your observations are pertinent and relevant. Allopatry (vicariant
replacement) requires dispersal to operate differently during
differentiation than other times when differentiation is not active. There
would appear to be many instances showing the dispersal capacity is not
inherent only to the organism, but also its ecology. Perhaps it is a case
that when that ecology changes drastically either through climate,
tectonics, or anthopogenic factors, what might operate over a narrow
geographic range previously now operates more broadly. And there are
instances of narrow endemics becoming weeds when transported into a new
habitat such as Pinus radiata that was once almost extinct but now acts
like a weed (albeit a profitable one) in New Zealand (in contast I once
observed an experimental planting of various pines in New Caledonia where
P. radiata showed the most dismal amount of growth).

Perhaps a nice example of biogeography and ecology is that of Coriaria and
Corynocarpus:

p. 102. The total distribution of Coriaria and Corynocarpus along the
Tethys and circum-Pacific (including Caribbean) belts corresponds to the
world's active subduction zones. Coriaria and Corynocarpus are subduction
zone weeds and have maintained this ecology over geological times scales,
surviving the high levels of disturbance ccaused by volcanism, earthquakes,
uplift, rifting and subsidence. The two plants are also weedy pioneers in
the ecological time scale, and are often conspicuous colonists of disturbed
habitat around cliffs, gullies and landslides.  Coriaria has interesting
records in the central Pacific (east to the summit of Tahiti, Society
Islands), a region characterized by high levels of volcanism since the
formation of the Pacific plate and the emplacement of the large ingneous
plateaus."

John Grehan


On Wed, Mar 26, 2014 at 4:18 AM, Fred Schueler <bckcdb at istar.ca> wrote:

> Quoting Michael Heads <m.j.heads at gmail.com>:
>
> > Surprisingly, even species with long-lived, planktonic larval stages also
> > show very high levels of geographic structuring.
> >
> > On Tue, Mar 25, 2014 at 7:26 PM, Stephen Thorpe
> > <stephen_thorpe at yahoo.co.nz>wrote:
> >
> >> Yes, marine species with direct development (no larval stage) can show
> >> local endemism (the sea to them is like the air to us!)
>
>
> * maybe we need a causally-based theory of local
> [co-?]adaptation/vicariance. Is there a literature of studies of the
> population biology of introductions in terms of understanding the
> biogeographic dispersalist/vicariance dispute?
>
> I'm inspired to suggest this by the failure of many alien species
> which, despite successful somatic growth, fail to reproduce in an
> alien landscape, most conspicuously widely planted trees (thank you,
> Picea abies). It's part of the standard understanding of invasion
> science that after a tenuous start of several to many generations, an
> introduced species may undergo a bit of selection for some local
> adaptation, and then become invasive.
>
> It seems to me that the preference for vicariance over dispersal as
> explanation for biogeographic patterns assumes that there's a general
> failure of dispersal events by waif individuals. Of course this would
> be hard to study, since the efforts of invasion biologists have
> demonstrated that it's very hard to even implement policy-mandated
> rapid-detection-rapid-response to extirpate new colonies of species
> known to be invasive, let alone study the population biology of new
> populations.
>
> Maybe a part of such a theory would be comparisons of taxa with
> different life histories such as the larval/direct development of
> marine species: the establishment of remote colonies of a taxon is an
> unobservable event, sort of like the Higgs boson, so we need a
> comprehensive theory of all aspects of its causes and consequences.
>
> written speculatively in nearly complete ignorance of any recent
> literature on this subject,
>
> fred.
> ------------------------------------------------------------
>           Frederick W. Schueler & Aleta Karstad
> Bishops Mills Natural History Centre - http://pinicola.ca/bmnhc.htm
> Mudpuppy Night in Oxford Mills - http://pinicola.ca/mudpup1.htm
> Daily Paintings - http://karstaddailypaintings.blogspot.com/
>           South Nation Basin Art & Science Book
>           http://pinicola.ca/books/SNR_book.htm
>      RR#2 Bishops Mills, Ontario, Canada K0G 1T0
>    on the Smiths Falls Limestone Plain 44* 52'N 75* 42'W
>     (613)258-3107 <bckcdb at istar.ca> http://pinicola.ca/
> ------------------------------------------------------------
>
>
>
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