Date: Sat, 12 Aug 2000 09:08:01 EDT From: Biodan@aol.com To: cp@opus.hpl.hp.com Message-Id: <aabcdefg2471$foo@default> Subject: Re: S. purpurea
Actually the evolving from a southern species to a northern species is quite
likely. Consider the climate changes over the past 10,000 yrs or so. With
the shrinking of the last ice cap over much of central North America, flora
and fauna have 'migrated' northward as temperatures warmed. (On Clingman's
Dome in the Smokey Mtn. Natl. Park is a remnant Spruce-Fir forest. The
closest similar forest is in Canada!) So, as the climate changed, plant (and
animal) populations were able to expand to the north. Then as a result of
individual genetic variation and natural selection, some species, including
S. purpurea, developed populations tolerant of warm temperatures (which
remained in the southern climes) and of cool temperatures which are able to
survive as far north as Canada where conditions are similar to those in the
southeast US during the last ice event.
Dan
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