[Taxacom] What exactly is or is not a Gondwanan distribution?
peterar at berkeley.edu
Wed Mar 27 14:43:14 CDT 2013
Is South Africa east of, or west of, South America ? (Now?, Then?)
Is the taxonomic placement of the "wayward" genus correct ? (Right Tribe?, Or is it a misplaced, and of a different, non-Gondwanan Tribe?)
Is the wayward genus a recent evolutionary development, having evolved from a Gonwandan "legitimate" So. Amer. taxon ? (split later than the Gondwanan split ?)
It seems that there are a number of taxon-specific bits of information that would need to be brought to bear on your question, the simplest of them being whether your statement about the genera of the particular tribe in question refers to a genus (or several genera) occurring in several of those locations, or if each genus is restricted to one or another of those locations ? I.e., how are those genera distinguished from the wayward genus other than the fact that the wayward genus is found "only" east of the Andes (and that all the genera are presently placed in the same tribe)?
At 12:17 13/03/27, Leavengood,John wrote:
> 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
>John M. Leavengood, Jr.
>University of Kentucky
>Department of Entomology
>S-225 Agricultural Science
>Center Building - North
>Lexington, KY 40546-0091
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