Re: Barriers to dispersal

[John Bois <jbois@umd5.umd.edu>]

There is great relatedness among NZ and Australian birds--is this from
migration or land connections--I think the former.  Quite a distance.  And
then, over an (arbitrary) 10 million year period, there can be storms,
rafts, etc., etc.  Islands in the middle of nowhere are populated
by avian species. Why not massive continents not so far from other massive
continents?

On Wed, 19 Dec 2001 NJPharris@aol.com wrote:

> In a message dated 12/19/01 4:05:14 AM Eastern Standard Time, 
> tommy.tyrberg@aerotechtelub.se writes:
> 
> > Things aren't quite that simple. Even rather narrow water gaps are
> >  actually rather strong barriers to bird dispersal, especially for
> >  landbirds.
> 
> Yeah.  Some species are particularly weird that way.  The Wrentit (_Chamaea 
> fasciata_), for instance, is the only North American babbler (timaliid), and 
> its ancestors must therefore have come over the Bering Land Bridge at some 
> point.  However, they are not now found anywhere north of Oregon, since they 
> apparently will not cross the Columbia River!
> 
> --Nick P.
>