[Drosophila] Re: initial population and inserts

Laurence Mueller via dros%40net.bio.net (by ldmuelle from uci.edu)
Wed Sep 12 12:00:07 EST 2012


Mark,
I guess I am not sure exactly what you are trying to do. On the one hand you
ask if you should select the first emerging flies so you can apply selection
for rapid development. But then you state that your lines are inbred. If you
have an interest in selecting for rapid development than inbred lines are,
of course, the worst material to work with. You should be using genetically
variable populations (not Oregon R) that have preferably adapted to the
"lab" environment.

Your earlier posts seem to deal with problems of bacterial growth and issues
about the composition of the fly medium. The larvae actually do best on
medium with active yeast populations (see references by Sang and others in
my publication #13). Most recipes for fly food I am familiar with put some
sort of acid in the fly food (e.g. propionic acid) which inhibits molds and
bacteria but is conducive to yeast growth. In the end I would suggest using
a fly food recipe others have used rather than re-inventing the wheel.

I'm sorry to hear my PNAS and Science articles were not useful. You may want
to look at publication #13 which reviews the lab ecology of Drosophila.
Larry


Laurence D. Mueller
Professor and Chair
Department of Ecology & Evolutionary Biology
University of California, Irvine
Irvine, CA. 92697-2525
Phone: 949 824-4744
FAX: 949 824-2181
web site: http://darwin.bio.uci.edu/~mueller

-----Original Message-----
From: dros-bounces from oat.bio.indiana.edu
[mailto:dros-bounces from oat.bio.indiana.edu] On Behalf Of Mark Thorson
Sent: Wednesday, September 12, 2012 9:23 AM
To: bionet-drosophila from magpie.bio.indiana.edu
Subject: Re: [Drosophila] Re: initial population and inserts

Laurence Mueller wrote:
> 
> The rover and sitter polymorphism is a larval behavior that is 
> naturally polymorphic in D. melanogaster populations.  Larval crowding 
> increases the frequency of the rover phenotype. Marla Sokolowski has 
> done most to the research on this behavioral trait and her 
> publications should be read to understand this trait. Larval and adult 
> crowding also has many non-trivial effects on the evolution of a host 
> of life-history traits in Drosophila too numerous to summarize here. 
> However, if you consult my web site below you will find ~20 years' 
> worth of research on this topic including some review articles.

Thanks for the link.  You certainly have a lot of experience!  Refs 2 and 29
didn't help me much, but 50 is great!  I'll have to read it again.
You mention some factors that I've been wondering about, such as the effect
of using adults from young vs. mature cultures.  In general, all of my
cultures are propagated when young, but I've been considering whether I
should propagate from the very first adults to emerge to apply selection
pressure favoring short life cycles.

I haven't been expecting much genetic variation in my cultures, which are
based on what I assume are a highly inbred strain.  Out of about 2000
cultures, I've only had one case of a wild fly somehow getting into a
culture and contaminating the genetics.

Currently, I propagate from the most vigorous cultures.  If there is any
genetic variation, I assume these are the winners.  I'm thinking more about
variation due to bacteria the flies carry with them on their feet and in
their gut.
Because I'm not sterilizing my media or using methyl paraben, I assume my
media has its own ecology of yeast and bacteria, and I believe a lot of the
variation in the productivity of my cultures is due to the bacterial
component.
My working theory is that good cultures have good bacteria -- bacteria that
don't overgrow the media or don't overgrow until late in the life of the
culture.

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