I really wanted to take this topic off Tweeters, because it seems to be
one of those technical questions of interest to very few people, which
will have most tweets hitting their D button in disgust. The general
interest for Tweeters is that we all, presumably, want ornithological
research to be based on very firm, reliable methods, and this one strikes
me as being too weird and shaky. Let me pass on part of what I wrote to
Mike Waller, somewhat edited, before Jim Neitzel's message came through.

The bulk of the material in bird or mammal poop consists of bacteria
(and their viruses). The lining of the intestine is always being
sloughed, so there must be DNA from those cells, but by the time it gets
down to the rectum I would imagine that it's largely degraded, and it's
certainly mixed up with the much larger amounts (I think) of bacterial
DNA. So this strikes me as a very weird approach to collecting
bird or mammal DNA.

If this guy uses PCR (polymerase chain reaction), he might have some
primers that would select out one particular sequence to study, one that
he knows (but how does he know?) is specific to the animal and not found
at all in the commensals. But that would only give him at most a thousand
or a few thousand base pairs compared with the enormous amount of DNA in a
mammalian genome. That seems like a terribly small sample of the genome
on which to base any conclusions about taxonomy or phylogeny. For such a
study, isn't it a whole lot easier and more reliable to take a small blood
sample?

Burt Guttman guttmanb at elwha.evergreen.edu
The Evergreen State College Voice: 360-866-6000, x. 6755
Olympia, WA 98505 FAX: 360-866-6794