Greg,

I agree with your analysis.   The genetic factor would undoubtedly be 
secondary to succession.

Paul

In a message dated 1/23/07 5:00:51 PM,  writes:


> Interesting question. Because the population had invaded the east so soon 
> before it started losing ground again, it may have had lower genetic 
> variability than a more established, big population would have and thus less ability 
> to adapt to changing conditions. But I think that would be a contributing 
> factor rather than a leading factor. I'm wondering if forest dynamics in the East 
> have been more dramatic than they have been out west. (There are lots of 
> places out west where shrubs are the climax vegetation, whereas in the East they 
> are almost always successional.)
> 
> Greg Butcher
> Director of Bird Conservation
> National Audubon Society
> 1150 Connecticut Avenue NW, Suite 600
> Washington DC 20036
> Tel.: 202-861-2242, ext. 3034
> Fax: 202-861-4290
> 
> 
> Protecting our Great Natural Heritage through the Important Bird Areas 
> program,<http://www.audubon.org/bird/iba>,
> and the WatchList, <http://www.audubon.org/bird/watchlist>.
> 
>