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Cloning and extinction



Patrick Norton wrote:
>
>Except for asexually reproducing organisms, of course.  But in a Jurassic
>Park-ish kind of way, the concept of extinction is debatable even for a
>vertebrate taxa with a current population of zero living members.  For
>example, if ongoing efforts to clone the *extinct* wholly mammoth are
>successful, will _M. primogenus_ be considered to have >recovered< from
>extinction---or will the resultant animal(s) be considered a new species
>entirely?

Despite the optimism of some groups, a recent study (Alex Greenwood et al,
"Nuclear DNA Sequences from Late Pleistocene megafauna," Molecular Biology
& Evolution, November 1999) could find no "single-copy" DNA -- that is,
chromosomal DNA that is part of the genotype -- longer than about 100 base
pairs in cold-preserved specimens of Pleistocene megafauna including
mammoths and sloths. DNA isn't very stable unless something is actively
repairing it (ie., during the life of the animal). They don't expect any
better from the long-frozen mammoth. Going from 100 base pair fragments to
the 2-3 billion base pairs in the entire genotype is rather much of a
challenge. There are more details in my report in the November 13 New
Scientist (page 11; I don't know if it's on the web site).

 Dinosaurs or even Mesozoic insects trapped in amber are going to be
considerably harder.

Jeff Hecht     Boston Correspondent    New Scientist magazine
525 Auburn St.,          Auburndale, MA 02466             USA
tel 617-965-3834 fax 617-332-4760 e-mail jhecht@world.std.com
URL: http://www.sff.net/people/Jeff.Hecht/
see New Scientist on the Web: http://www.newscientist.com/