SUBJECT: Quantitative genetics
DATE: 12/95
Biolabbers,
We are considering adding a quantitative genetics exercise to our Mendelian
genetics lab which uses fruit flies. Can anyone suggest some characteristics
that might be easy to measure and show different heritabilities? Bristle
number and wing venation patterns come to mind, but I have no experience
with either of these. Thanks.
Steve Rice
ricesk@wfu.edu
Core Curriculum Coordinator
Wake Forest University
Steve Rice (ricesk@wfu.edu) raises an good idea to get
quantitative genetics into our courses. I don't have experience
with any of these systems, but how about doing something with
internode length? The classical system would be peas, which
would have a nice historical tie-in since Mendel considered this
character and avoided it precisely because it was quantitative.
To do peas in a student lab, one would have to produce F2 seeds
ahead of time, but it should be possible to germinate them and
measure the phenotype within a quarter.
This system also has the instructive element of a strong and
simple environmental influence, namely light. Growing plants in
pots next to each other in full light and shade should provide
interesting material for analysis. Meaningful statistics too.
What do y'all think? Has anyone done this? Another idea could
be to use Arabidopsis, would that be fast enough to allow a
cross to be set up and analysed in one term?
Please excuse my woeful ignorance of plants. Viruses are more
my thing, if that is any excuse.
----------------------------------------------------------------------
Walter Ogston ogston@hobbes.kzoo.edu
Department of Biology Phone: (616)337-7010
Kalamazoo College Fax: (616)337-7251
Kalamazoo, MI 49006-3295
Let me run another idea past everyone. For several years in my general
biology class we collected student height (in inches and without shoes).
Data collected over the period of six years exhibited very nice bell curves
and also sexual dimorphism with the peak of the female bell at about 65
inches (n=661) and the peak of the male bell at about 72 inches (n=428).
The major difficulty we had was students measuring incorrectly or just
putting down what they thought to be their height. For a long time I have
wanted to expand this to include measurement of several features, perhaps
contributing to height (lengths leg bones, vertebral column, height of
cranium) to demonstrate variability within variability, and/or other
features (size of nose, size of ears, circumference of cranium, color of
eyes, color of hair, etc. etc. etc. In other words, why not use the human
animal as the source of measurement to demonstrate variability and
especially quantitative inheritance? Has anyone done this? If so, what
are the pitfalls?
Sincerely,
Roger Christianson 503-488-0223 (home)
Department of Biology 503-552-6747 (office)
Southern Oregon State College 503-552-6415 (fax)
1250 Siskiyou Boulevard rchristi@wpo.sosc.osshe.edu
Ashland, OR 97520
It is certainly good to get students realizing that genetics applies to
people as well as plants, but I believe we should focus on the unity of
life.
Also we should be very careful to avoid reinforcing the popular myths
about human genetics, some of which are perpetuated in the text books.
If one is going to do the stuff Roger suggests, I think it
should be in conjunction with reading Steven Jay Gould's "The
Mismeasure of Man".
The other problem I have with just measuring the distribution of heights
in a class of students is that it doesn't directly teach any genetic
lesson. Is it practical to regress the heights of the students on those
of their parents? How good would the available data be?
----------------------------------------------------------------------
Walter Ogston ogston@hobbes.kzoo.edu
Department of Biology Phone: (616)337-7010
Kalamazoo College Fax: (616)337-7251
Kalamazoo, MI 49006-3295
Isn't there some good quantitative exercies associated with the Wisconsin
Fast Plant model system. I seem to remember a Grade 4 class determined to
breed the hairiest plants.
This model system could be useful for demonstrating the variability as well
as testing predictions regarding response to selection etc.
One could compare known single-gene traits with quantitative traits.
The Carolina Catalogue has more info, seeds, etc.
Tom
Tom Haffie Phone: 519-679-2111 (6502)
Department of Plant Sciences FAX: 661-3935
University of Western Ontario e-mail: thaffie@julian.uwo.ca
London, ON, Canada
N6A 5B7
'Labbers,
Why not use fast plants (Brassica rapa) for this? The number of hairs on
stems and leaves is a quantitative trait. Hair [Hir (5-8)] and Hairless
[Hir (0-2)] seeds can be purchased from Carolina or The Crucifer Genetics
Society. P1s can be sprouted on the first day of a semester-long course
and F2 seedlings can be analyzed during the last week before finals -- I
know, my class just finished this today (not using the hirsuit trait,
though).
Gary Meeker
Dept. of Biological Sciences
California State Universit
Sacramento, CA 95819-6077
gmeeker@csus.edu
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