Government views Monarch Butterfly Releases as a threat to We stern Milkweeds

Paul Cherubini monarch at
Fri Dec 7 23:56:16 EST 2001

Ken Kaufman wrote:

> Paul,  Thank you for passing along this very well reasoned opinion
> from Dr. Karen Oberhauser.  Her points are certainly persuasive,
> and provide more strong reasons to avoid shipping Monarchs any
> distance for release.  I'm glad to see you providing something
> useful to the discussion this time.

Ken, I personally have a difficult time understanding the scientific basis of
Dr. Karen Oberhauser's concerns. I ask myself, are they reasonable, legitimate 
scientific concerns based on a negligible risk standard or are they questionable
concerns based on a zero risk standard?  Perhaps you can help me understand
the scientific basis of some of Dr. Karen Oberhauser's concerns.

Karen says "there is evidence that monarchs become genetically differentiated 
[based on the old, 1978  method of using  protein (electrophoretic) markers]
by the end of the summer," and "If shipping monarchs from Minnesota to 
Maine has even the slightest chance of disupting genetic structure, or of
making it difficult to study that structure, I don't think we should do it."

Ken, what I'd like you to do (or anyone else on the list) is is explain 
how a modest amount of human assisted shipping of Minnesota
monarchs to Maine (or vice versa) has even a slight chance of disrupting
the genetic structure of the recipient population or how these introductions could
make it difficult for a researcher to study that structure in late summer?

Dr. Bruce Walsh at the  University of Arizona, Tucson, offered
the following analysis of these questions last year:

Bruce wrote:

"The short answer to the issue of releases confusing studies of local population 
structure is that this is indeed correct with the older methods of using protein 
markers (electrophoretic markers) to look at population structure. However, 
the point is somewhat moot for several reasons.

First, releases are likely to be such a very small proportion of the population 
as to not likely be sampled in any random sample of the population used to 
examine local structure.

Second, suppose that indeed a very genetically different strain is released 
and somehow incorporated into a random sample from the population that
is used for looking at population structure. Typically, researchers use 
genetic markers to reconstruct what amounts to a phylogenetic tree of 
relationships among individuals (marker genotypes) in the sample. Any 
distinct individual from the new population will show up as major outliners on
the tree, with no connecting individuals. If such a tree is not attempted to be
reconstruct, these individuals can give larger Fst (a statistical for population 
structure) than is indicated by the true population. However, studies failing to 
attempt to reconstruct the local phylogeny are very poorly done and are unlikely 
to be published under today's standards.

Third, DNA markers are now the norm. Unlike protein markers, one 
can use dead museum material in many cases for DNA. Hence,
material predating any release is likely available if the research simply 
looks in local collections. Further, using tightly-linked genetic
markers (SNPs, for single nucleotide polymorphisms), it is again 
straightforward to find those individuals that are very distinct, and
again we expect gaps between the local individuals and the released

In summary, unless the released material makes up a significant fraction 
of the local breeding population (at least over 1 percent and likely over 5 percent), 
it is unlikely to be obtained in a random population sample. Even if such
distinct genotypes are included, standard methods using DNA markers 
to look at population substructure can detect such extreme, outliers, and 
hence these do not compromise the studies."


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