[Taxacom] What exactly is or is not a Gondwanan distribution?

[John Grehan]

Perhaps the simplest answer is that a gondwanan distribution is
biogeographically one in which the relationships and massings point to a
link across the Indian Ocean. Attempts to define gondwanan distribution in
terms of a particular geography or geological scenario can run into
arbitrary problems. For example, Nothofagus occurs in NZ, Australia,
Antarctica and S. America and one might say that because these lands were
once part of Gondwana, the distribution pattern also conforms in this
regard. But in terms of massings and relationships Nothofagus does not
conform to a gondwanic origin but conforms to the pattern of a Pacific
group that merged with gondwanan margins.

John Grehan

On Wed, Mar 27, 2013 at 3:17 PM, Leavengood,John <tokay at ufl.edu> wrote:

> Hello, everyone.
>
>    I am not well-versed in biogeography; hardly versed at all, in fact.
> I have encountered many references to Gondwanan distributions often
> pointing to taxa which span Australia, New Zealand, Southern Africa and
> Chile/Argentina bound by the Andes.  Definitions seem to match this
> notion.  So if a taxon (say, a tribe) has genera in New Zealand,
> Australia, Chile and Argentina, but one genus among them occurs only
> east of the Andes from northern Argentina all the way to Guatemala, is
> that tribe still considered of Gondwanan distribution?
>
> Why or why not?  Or perhaps it points to a certain type of Gondwanan
> distribution attributed to a particular timeframe facilitating that one
> lineage propagated east of the Andes but has no members west of them?
>
> I would appreciate answers accompanied by references, but all guidance
> is appreciated.
>
> --
> --------------------------
> John M. Leavengood, Jr.
> Doctoral Candidate
> University of Kentucky
> Department of Entomology
> S-225 Agricultural Science
> Center Building - North
> Lexington, KY 40546-0091
> (859) 257-3169
>
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