Government views Monarch Butterfly Releases as a threat to We stern Milkweeds
Paul Cherubini
monarch at saber.net
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
individuals.
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."
------------------------------------------------------------
For subscription and related information about LEPS-L visit:
http://www.peabody.yale.edu/other/lepsl
More information about the Leps-l
mailing list