Releasing Monarchs

Patrick Foley patfoley at
Fri May 23 14:38:21 EDT 1997

The release of nonlocal strains of butterflies involves several important 
hazards which have been discussed briefly over the last few months. A 
superficial analysis may give the pro-release position some support, but 
it is a humbling experience to consider how little we know about 
butterfly genetics and how often species releases (not genetic strain 
releases) have led to ecological disaster. 

In a previous note, I suggested among other dangers of nonlocal gene 
mixing these concerns: transposons, runaway sexual selection genes, 
diseases. Bruce Walsh said he agreed with me on every point, although he 
felt that a few crosses would clear up the uncertainties. In practise, 
the clarifying crosses are not being made, will not be made, and would 
take too long to evaluate to deal with present planned releases. Bruce 
and I both have PhD's in population genetics (his U Washington, mine UC 
Davis). I think that few population geneticists would rush blindly into 
nonlocal releases, and I am surprised that nonpopulation geneticists feel 
that the problems are trivial. Bruce is more pro-release than I am, some 
geneticists would probably be more anti-release thatn I am, but I want to 
go on record in rejection of the analyses presented below!

patrick foley
patfoley at

On Thu, 22 May 1997, Paul C Weaver wrote:

> Finally someone with some good practical population biology knowledge on
> this subject. Genetic diversity is through numbers. There's is no major
> artificial selection going on here, the population is not being infused
> and confined through numerous generations. IF anything the release of
> captive monarchs should help the native population to a small degree.
> Monarchs are a strong species that have overcome many obstacles in their
> evolutionary journey on planet earth. The freeze in Mexico would have
> changed the gene pool to a far greater extent than any breeder will even
> come close.  Breeders always seem to get a bad rap but the biological
> knowledge they obtain on captive lepidoptera is extremely valuable to the
> scientific community.
> Thanks
> Paul
> On Thu, 22 May 1997, Bob Greback wrote:
> > I don't think anyone on this list can tell me how many reared monarchs it 
> > would take to change the genome of any "regional" population of monarchs as to 
> > notice ANY difference harmful or otherwise.  Unless your exposing them to 
> > radiation to increase the genetic load (and even that would probably not be 
> > enough), it would take one farfetched or astronomical piece of "luck" to rear 
> > a population with chaotic enough alleles to do any "damage" or change the 
> > region's or nation's monarch population in any noticeable way.  They are 
> > migratory and have a high degree of dispersal built into their ethology.  
> > There's no artificial selection going on here, the population is not being 
> > infused and confined through numerous generations. 
> > 
> > I wonder what E.O. Wilson would have to say about the infusion of reared stock 
> > into natural populations.  Probably not much.
> > 
> > Thanks!
> > Bob Greback
> > 

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