[Taxacom] Test Questions (was: Panbiogeography)

Mon Apr 7 02:40:56 CDT 2014

Hi Richard,

Speciation by 'chance dispersal' may well occur, but by definition would
not result in a standard distribution pattern. I'd be interested in any
possible cases.
   As for groups other than higher plants and animals, here are two
examples. Both show the same thing that has been found in many marine
groups since sequencing began - high levels of phylogeographic structure
not predicted in the dispersal paradigm.

   Molecular studies of soil rotifers found 'surprising' and 'unexpected'
structure (Robeson et al., 2011):

Local communities show *strong spatial structuring*, whereas more distant
communities are very different from one another, even in similar
environments... This world view directly contradicts the idea of EisE
[everything is everywhere] and suggests that the diversity of microbial
eukaryotes such as rotifers may be vast beyond our imagining, especially
given that endemic microbes may have *species ranges of about 100 m*...
Bdelloids are known to produce small, resistant resting stages... that
should disperse easily by wind. The fact that our results show that
bdelloids are not widely distributed implies that other microbial
eukaryotes with less resistant stages... should have even more
geographically restricted distributions...  the ability to form resistant
stages probably evolved not for dispersal but to survive periods of
unfavorable environmental conditions (i.e., dry and cold conditions)...
thereby maintaining unique local communities. [Italics added].

   Allopatry even exists in bacteria and a survey *of *the global
genus *Chroococcidiopsis
**concluded: *

Temporally scaled phylogenetic analyses showed no evidence of recent
inter-regional gene flow, indicating populations have not shared common
ancestry since before the formation of modern continents... although a
desert cyanobacterium such as *Chroococcidiopsis* may notionally possess
the characteristics for ubiquitous dispersal due to aeolian transport of
desert particulates and its desiccation/radiation tolerance..., this is not
reflected in contemporary colonization [i.e. distribution] patterns. The
existence of regionally isolated gene pools of hot and cold
*Chroococcidiopsis* variants strongly supports the concept that widespread
contemporary dispersal is not common, and that relationships reflect
ancient historical legacies. Although strong selection for hot and cold
variants has occurred, this pre-dates contemporary climatic selective
pressures... (Bahl et al., 2011).

On Mon, Apr 7, 2014 at 5:12 AM, Richard Pyle <deepreef at bishopmuseum.org>wrote:

> Hi All,
>
> I've only been partially paying attention to this thread, but Jason's
> recent
> post (which captured my own general perspective nicely) has encouraged me
> to
> ask some questions:
>
> 1) Does everyone agree that there is ample evidence that some populations
> of
> organisms have been fractioned via rare vicariant events, leading to
> reproductive isolation and subsequent divergence and, ultimately,
> speciation?
>
> 2) Does everyone agree that there is ample evidence that some populations
> of
> organisms have been fractioned via rare dispersal events, leading to
> reproductive isolation and subsequent divergence and, ultimately,
> speciation?
>
> If anyone's answer to either question is "No", I would like to hear an
> explicit statement of such, accompanied by explanations that counter the
> aforementioned ample evidence (which has been, and could easily be,
> provided
> by members of this list) in specific, individual situations.
>
> If we all agree that the answer to both questions is "Yes", then can
> someone
> explain what this seemingly never-ending debate is really about?  Is it
> simply about the relative frequency of each mechanism, across broader
> biodiversity, that has historically resulted in reproductively isolated
> populations and subsequent speciation?  If so, then the next question is:
>
> 3) Are we arguing about 95/5 one way or the other, or more like 60/40 one
> way or the other?
>
> Some additional questions:
>
> 4) Is anyone willing to step up to the plate to discuss cases where
> speciation seems to have occurred in the absence of geographic isolation
> (i.e., no dispersal or vicariant events required)?
>
> 5) Does someone want to take a stab at defining the scope of "broader
> biodiversity" alluded to in the preamble to question #3 above? (There seems
> to be a lot of focus on terrestrial vertebrates and plants -- does the
> debate also include marine organisms?  What about insects?  Microbes? Can
> vicariance or dispersal explain patterns of bacteria diversity?)
>
> 6) Imagine a hypothetical(?) situation where infrequent events like global
> glaciation cycles cause substantial sea-level changes, which have dramatic
> impact to ocean currents and thereby shifts in patterns of dispersal
> potential/frequency among marine organisms with planktonic larvae -- such
> that geographically disjoint populations that have high potential gene flow
> during long periods of time, undergo long periods of time with very low
> potential gene flow.  In such cases, where speciation results during the
> low-gene-flow periods, do we score a point for vicariance, or for
> dispersal?
>
> Aloha,
> Rich
>
>
> Richard L. Pyle, PhD
> Database Coordinator for Natural Sciences
> Associate Zoologist in Ichthyology
> Vicariant Dispersalist
> Dive Safety Officer
> Department of Natural Sciences, Bishop Museum
> 1525 Bernice St., Honolulu, HI 96817
> Ph: (808)848-4115, Fax: (808)847-8252
> email: deepreef at bishopmuseum.org
> http://hbs.bishopmuseum.org/staff/pylerichard.html
>
>
>
>
> > -----Original Message-----
> > From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-
> > bounces at mailman.nhm.ku.edu] On Behalf Of Michael Heads
> > Sent: Sunday, April 06, 2014 12:17 AM
> > To: JF Mate
> > Cc: Taxacom
> > Subject: Re: [Taxacom] Panbiogeography
> >
> > Hi Jason,
> >
> > Getting back to the facts, a taxacomer just sent me a classic that I
> hadn't
> > spotted: a chameleon on Socotra that has a diverse sister group
> widespread
> > through the Sahel (Mali to Somalia), around the Mediterranean, Saudi
> Arabia
> > and east to India (not on Socotra). It's in Macey et al., 2008 Mol
> Phylogen Evol
> > 49: 1015.
> >
> > This is the sort of thing you see in many groups in the Caribbean and the
> SW
> > Pacific. It's very simple to explain the pattern by an early break in a
> > widespread ancestor, somewhere around Socotra. If you want to explain it
> > by the usual dispersal from the mainland, you have to bring in other, ad
> hoc
> > hypotheses. But the main point is just how starkly and beautifully it
> highlights
> > the significance of Socotra, whatever the actual mechanism.
> >
> > Michael
> >
> >
> > On Sun, Apr 6, 2014 at 7:08 PM, JF Mate <aphodiinaemate at gmail.com>
> > wrote:
> >
> > > Hi Ken. Sorry for replying so late but i am currently travelling
> around.
> > > Your optimism is refreshing but ultimately a waste of effort. There is
> > > no evidence that you can offer them that will satisfy them because you
> > > don't know (or them I suspect) what they are arguing against. Whereas
> > > you, I or most others can accept vicariance and dispersal as
> > > mechanisms (and have said so repeatedly) we are labelled dispersalists.
> Go
> > figure.
> > > When you show them clear, factual evidence of organisms being sent
> > > across the ocean, these events are either "too frequent" or so
> > > infrequent that the probabilities cannot be calculated and therefore
> > > no different to astrology (so much for only being interested in data).
> > > What you will never be shown are the definitions under which they
> > > operate. Funny since they are interested in patterns and this requires
> > > some sort of operational definitions. But when a man's livelihood
> > > depends on not understanding something, then they won't, no matter
> > what you say.
> > > "It doesn't matter how beautiful your theory is, it doesn't matter how
> > > smart you are. If it doesn't agred with experiment, it's wrong." Stuff
> > > can cross oceans, let them fight facts if they want. I have critters to
> catch.
> > >
> > > Best
> > >
> > > Jason
> > > _______________________________________________
> > > Taxacom Mailing List
> > > Taxacom at mailman.nhm.ku.edu
> > > http://mailman.nhm.ku.edu/mailman/listinfo/taxacom
> > > The Taxacom Archive back to 1992 may be searched at:
> > > http://taxacom.markmail.org
> > >
> > > Celebrating 27 years of Taxacom in 2014.
> > >
> >
> >
> >
> > --
> > Dunedin, New Zealand.
> >
> > My recent books:
> >
> > *Molecular panbiogeography of the tropics.* 2012. University of
> California
> > Press, Berkeley. www.ucpress.edu/book.php?isbn=9780520271968
> >
> > *Biogeography of Australasia:  A molecular analysis*. 2014. Cambridge
> > University Press, Cambridge. www.cambridge.org/9781107041028
> > _______________________________________________
> > Taxacom Mailing List
> > Taxacom at mailman.nhm.ku.edu
> > http://mailman.nhm.ku.edu/mailman/listinfo/taxacom
> > The Taxacom Archive back to 1992 may be searched at:
> > http://taxacom.markmail.org
> >
> > Celebrating 27 years of Taxacom in 2014.
>
>

-- 
Dunedin, New Zealand.

My recent books:

*Molecular panbiogeography of the tropics.* 2012. University of California
Press, Berkeley. www.ucpress.edu/book.php?isbn=9780520271968

*Biogeography of Australasia:  A molecular analysis*. 2014. Cambridge
University Press, Cambridge. www.cambridge.org/9781107041028