Jane McGary
Tue, 23 Dec 2003 10:38:20 PST
Mark McDonough's reaction to the proposed reorganization of the genus 
Scilla is similar to mine, though I had not thought about it in such 
detail. In addition to Allium, one can easily think of many other genera 
which display differences in, e.g., seed morphology similar to those 
offered as the basis of genus differentiation in "Scilla nova." Calochortus 
is a good example for seeds, and for bulb and root form Iris is obvious. 
There are anomalous bulbs or corms in many genera -- for example, there are 
a few stoloniferous species in Crocus, Fritillaria, and Lilium.

I would like someone who actually does taxonomy based on DNA studies to 
clarify something for me. As I understand it, these studies are based on 
certain selected portions, or segments, of a few certain chromosomes -- not 
on the whole genome of the plant, which would not be feasible with present 
technology. How does the researcher know that the sequence(s) selected 
represent the variation in the entire genome in a meaningful and 
statistically reliable way?

I am not a scientist, but linguists employ rather similar statistical 
analyses to estimate the degree to which various languages are related and 
the time depth of their divergence from common ancestors. One currently 
popular method, called mass comparison, is capable of generating extremely 
dubious results if done on a database that is not, shall we say, perfectly 
understood by those conducting the comparison.

I think that quite a few of us on this forum have studied enough statistics 
and science to understand a brief answer to these questions, and we 
probably all have some grasp of genetics, so if someone appropriate has the 
time, would you please enlighten us?

Jane McGary
Northwestern Oregon

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