Pop. Genetics of releases

Morigi, Christine Christine.Morigi at studiosusa.com
Thu Sep 23 18:38:21 EDT 1999

Dear Bruce:

FINALLY! Now maybe I can get some sleep without worrying that the box of
caterpillars I brought to my kids' school may unleash the
butterfly-equivalant of the ebola virus!

-----Original Message-----
From: Bruce Walsh [mailto:jbwalsh at u.arizona.edu]
Sent: Thursday, September 23, 1999 3:28 PM
To: Lep List
Subject: Pop. Genetics of releases

Well, all this release debate has caused my to put down my net (actually,
clippers in this case, as I've been caterpillar hunting today, the
Saturnide Agapema homogena has larvae everywhere in the Santa Catalinas) and
on my professorial hat as a Professor of Population Genetics to offer
some comments.  The reasons are mainly selfish --- it takes me five minutes
to find those e-mail from my desperate Genetics students (they have an exam
on Friday) among all the Leps-postings.

First, I completely agree that some species should not be released, but
I'm dumfounded as to the excuses raised for the small-scale release others.
 For example, Painted lady butterflies are world-wide, and the size of
release to impact even a local population would have to be Manhattan-project
in scale.  Ken Phillips' point about separating "true" rare migrants from
releases is somewhat of an issue, but  many of those "true" migrants
simply hopped a ride on a car, plane, or boat themselves, in which case they
would be biologically meaningless from the standpoint of trying to
understand historical patterns.  Pat Foley (with whom I was a graduate
many years ago) suggests that such data is critical to understanding the
patterns, but as Monty Slatkin has shown DNA data provided a much better
picture of historical migrations than direct observations, even those over

As to dumping on poor Paul, he simply is ask ALL of us to DO SCIENCE.  If
you can't put in into numbers, its not science.  If release poses
a risk, demonstrate the conditions underwhich it can.  My counter (to
show that it does not have an impact) is that from simple population
theory, for a gene to spread that is opposed by selection (all those bad
genes the no-release folks are worried about), it must be pumped into the
population (via migration) at a rate which exceeds that at which it is
removed.  For example, if the gene as a 5% reduction in fitness, one must
pump in migrates equal to 5% of the entire population just to keep the gene
in place, much less cause it to spread.



PS.  Perhaps we should start a creationist/evolution angle to this thread
to completely  eat up all the bandwidth.

Bruce Walsh
Associate Professor
Department of Ecology and Evolutionary Biology
Biosciences West
University of Arizona
Tucson,  AZ  85721  USA

email:   jbwalsh at u.arizona.edu
Office:  520 621-1915
Fax (Departmental)  520 621 9190

home page:  http://nitro.biosci.arizona.edu

Quantitative Genetics page:  http://nitro.biosci.arizona.edu/zbook/book.ht

Arizona Moths page: http://nitro.biosci.arizona.edu/zeeb/butterflies/mothl

Arizona butterflies page: http://nitro.biosci.arizona.edu/zeeb/butterflies

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