Locality data

Nhu Nguyen xerantheum@gmail.com
Thu, 01 Nov 2012 20:55:01 PDT
Jim Shields wrote:

> I think that a future definition(s) of "species" will attempt to
> circumscribe the "envelope" of DNA sequences that are encompassed by a
> given species.  This answer will probably be different for different
> species.  I think it will be very different for plants than for animals;
> and microbiologists seem to have already gone off on their on very separate
> track for defining populations rather than species.  Binomial nomenclature
> seems to be giving way to serial numbers that computers can more easily
> handle.  You don't draw pictures of phylogenetic trees, you calculate new
> ones using the latest data as you need them.  Today's tree won't look like
> yesterday's unless the databases were locked down overnight.

Jim, from your spectator status, you have formulated a completely
clairvoyant nature of this field and where it's heading. I raise my cyber
wine glass to you!

Dylan et al.,
I think field work is the best part and I could never do without it, but I
would argue that a good body of work could still be produced from studying
in herbaria alone, given that the specimens are adequately preserved and
that there are lots of them that represent the range of the species. There
are limitations to what can be done in the field. How often does a
taxonomist have the time and funding to spend a month in the field? And
even if you think you're there at the right season, you may not find what
you're looking for. Even in the most productive field season, you will most
likely be missing the range of material that good herbaria have accumulated
over the years.

Those who actually do field work and even grow their own material for study
can gain a lot of information about the organism when observed in their
living state. This is another important reason to support living
collections. When I studied California onions, I relied on material fresh
from the field, the herbarium, and the living collection at the UCBG. All
of these complemented each other.

For the systematist, field work is often necessary because of the degraded
conditions of many herbarium species. 100 years, and even 200 years may not
be a problem for morphology, but even in the best preserved state,
specimens that are older than 50 years often yield poor quality DNA so
degraded that it can't be used. Some major herbaria used to heat their
specimens periodically to kill the pests; unfortunately it also kills the
DNA through the heat cool cycles. Herbaria have learned their lessons and
now freeze their specimens instead. The bright side to all of this is that
it brings people back into the field and thus completing the circle.


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