mesibov at SOUTHCOM.COM.AU
Thu Jul 11 20:02:38 CDT 2002
'I always considered myself a "lineage" type of guy, to the extent that my
working conception of a species is merely a terminal lineage branch. ...my
concerns are with the relationships amongst isolated lineage branches -
relationships above the species level - where niether taxa nor their
relationship suffer from the "blurriness" you mention.'
Your taxa and their relationships are the result of a blurring of the
genetic and temporal details of the group's history. Populations get
blurred into subspecies, subspecies get blurred into species; the slow,
two-steps-forward-one-step-back separation of lineages gets blurred into a
single cladogram node. Blurriness isn't a flaw in a phylogeny, it's
essential for a usable outcome. For a more highbrow discussion, see R.J.
O'Hara, Systematic Biology 42: 231-246 (1993).
Part of the problem with using spatial data in systematic studies is that
taxonomic results are often much less blurred than the corresponding
geography. There are highly 'mosaic-ed' places on this planet which
unfortunately are thought of as wholes by taxonomists. Neither of the
following statements (which I just made up) are particularly illuminating:
"There are 60 species of Improbablus in Myanmar"; "The 30 biogeographic
regions of Myanmar are home to the genus Improbablus". It's only by asking
questions about how the 60 species fit in the 30 regions that you can get a
handle on Improbablus history, which includes, but is not limited to, the
relationships of those 60 species.
Dr Robert Mesibov
Honorary Research Associate
Queen Victoria Museum and Art Gallery
Home contact: PO Box 101, Penguin, Tasmania, Australia 7316
(03) 64371195; 61 3 64371195
More information about the Taxacom