Transgenic fish could threaten wild populations

From: "S.Wilson" <fmoola@sprint.ca>
To: "Sustainable Maritimes" <sust-mar@chebucto.ns.ca>
Date: Thu, 27 Jan 2000 09:02:01 -0400
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Return-Path: <sust-mar-mml-owner@chebucto.ns.ca>

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Hello friends,


the following is an article and abstract detailing a recent study carried
out
Purdue University on the impacts of transgenic fish on wild populations.
Using a tiny fish called a medaka as their model organism, the researchers
found that males carrying a gene modified for increased growth (gene
construct containing human growth hormone driven by Atlantic salmon growth
promoter) were much more successful than non-transgenic males in obtaining
mates.   The authors concluded that "transgenic fish are typically larger
than the native stock, and that can confer an advantage in attracting
mates". However, this genetic change also reduced the survivability of the
offspring of transgenic males. On the basis of these results, the
researchers predicted that transgenic fish could bring a wild population to
extinction in 40 generations.  I've included the aricle and abstract of the
study below. This information was published originally by the Purdue
University Press and released to the world using the on-line Ecolog Listserv
of the Ecological Society of America.
http://news.uns.purdue.edu/html4ever/0002.Muir.trojan.html


cheers


Faisal Moola
Ph.D.. candidate
Dalhousie University
Halifax, N.S.


Purdue News


February 2000



Transgenic fish could threaten wild populations


WEST LAFAYETTE, Ind.

Purdue University researchers have found that releasing a transgenic fish
to the wild could damage native populations even to the point of
extinction. A transgenic organism is one that contains genes from another
species. The Purdue research is part of an effort by Purdue and the U.S.
Department of Agriculture to assess the risks and benefits of
biotechnology and its products, such as genetically modified fish. The
study was published in November in the Proceedings of the National Academy
of Science. 

[. . .]

Sources: Bill Muir, (765) 494-8032; bmuir@purdue.edu
Rick Howard, (765) 494-8136
Writer: Chris Sigurdson, (765) 494-8396; sig@aes.purdue.edu
Purdue News Service: (765) 494-2096; purduenews@uns.purdue.edu




ABSTRACT

Possible ecological risks of transgenic organism release when transgenes
affect mating success: Sexual selection and the Trojan gene hypothesis
William M. Muir and Richard D. Howard.  Widespread interest in producing
transgenic organisms is balanced by concern over ecological hazards, such
as species extinction if such organisms were to be released into nature.
An ecological risk associated with the introduction of a transgenic
organism is that the transgene, though rare, can spread in a natural
population. An increase in transgene frequency is often assumed to be
unlikely because transgenic organisms typically have some viability
disadvantage. Reduced viability is assumed to be common because transgenic
individuals are best viewed as macromutants that lack any history of
selection that could reduce negative fitness effects. However, these
arguments ignore the potential advantageous effects of transgenes on some
aspect of fitness such as mating success. Here, we examine the risk to a
natural population after release of a few transgenic individuals when the
transgene trait simultaneously increases transgenic male mating success
and lowers the viability of transgenic offspring. We obtained relevant
life history data by using the small cyprinodont fish, Japanese medaka
(Oryzia= s latipes) as a model. Our deterministic equations predict that a
transgene introduced into a natural population by a small number of
transgenic fish will spread as a result of enhanced mating advantage, but
the reduced viability of offspring will cause eventual local extinction of
both populations. Such risks should be evaluated with each new transgenic
anim= al before release. 



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