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Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!uakari.primate.wisc.edu!ginosko!uunet!munnari.oz.au!csc!dxb105
From: dxb105@csc.anu.oz (David Bofinger, Theoretical Physics, RSPhysS ANU)
Newsgroups: sci.space,sci.bio
Subject: Ecosystemic Contamination
Message-ID: <767.25311054@csc.anu.oz>
Date: 9 Oct 89 21:40:36 GMT
References: <8909272147.AA01656@aristotle.Jpl.Nasa.Gov> <2035@frog.UUCP> <5661@portia.Stanford.EDU>
Organization: Computer Services, Australian National University
Lines: 25

I'm cross-posting this to sci.bio, partly to get this line of the conversation
out of sci.space, and partly in the hope an expert can help out.

In article <5661@portia.Stanford.EDU>, joe@hanauma.stanford.edu (Joe
Dellinger) writes:
> Well, I would tend to agree with you, but there are precedents to
> the contrary. South America is a much larger continent than North
> America,

I suppose in biomass terms this is probably true.

> so you would expect it to be able to "hold its own"
> evolutionarily against invaders... and yet when the isthmus of Panama
> formed (quite recently geologically speaking) the North American mammals
> almost _immediately_ spread South and _totally wiped out_ all the native
> South American mammals.

I think the point was that South America was isolated. North America had a
(tenuous) link to the _real_ powerhouse of terrestrial evolution- Afro-Eurasia.
It wasn't North American mammals that colonised South America: it was Asian
ones, via the Bering strait.
______________________________________________________________________________
David Bofinger	ACSNet:	dxb105@phys0.anu.oz [@munnari.oz.au] (Australia)
                Snail:	Dept. of Theoretical Physics, RSPhysS, ANU, ACT, 2601
Annex space now. Canada wants us to, and Tom Neff can't stop us.