Transgenic fishes are nearing commercialization for aquaculture around the
world. Farmed transgenic fish would likely escape from typical production facilities and
interbreed with wild relatives. We tested methodologies for predicting the risk of gene
flow from transgenic fish.
We conducted the first study of gene flow in confined populations of transgenic
animals. In two experiments several generations long, we released growth-enhanced
transgenic (T) Japanese medaka (Oryzias latipes) into populations of wild-type (W)
medaka in semi-natural environments. Transgene frequencies varied in the first
experiment, but transgene frequencies all decreased in the second experiment. We
measured six fitness traits in both genotypes, and found that T males were more fertile
than W, but W males obtained more matings than T males.
Next, we compared fitness traits of W and T medaka under four environments:
(A) high food availability, predation absent; (B) high food availability, predation present;
(C) low food availability, predation absent; and (D) low food availability, predation
present. Overall, T females were more fecund than W, and fecundity was highest in
Environment B. Offspring of TW and WT crosses had higher survival to sexual maturity
than offspring of two W parents. Fish in Environment A reached sexual maturity sooner
than fish in all other environments. W males had a mating advantage in Environments B
and C. Finally, we observed gene flow in populations of T and W medaka in Environments
A-D for 210 days. The final transgene frequency in Environment A was greater than in
Environments C or D. We parameterized a demographic model with fitness trait values
collected under the same environments, which predicted that transgene frequency in
Environment A would be the highest, but also overestimated transgene frequency
compared to observed results. Predicted transgene frequencies overlapped with
observations in Environments B and C but not in the more extreme Environments A and
Our results suggest that risk assessment of gene flow from T to W fish ought to
consider the impact of limiting environmental factors on fitness components. Before
using models to inform ecological risk assessments, predictions should be confirmed with
data collected under relevant environmental conditions.
University of Minnesota Ph.D. dissertation. January 2010. Major: Conservation Biology. Advisor: Anne R. Kapuscinski. 1 computer file (PDF); x, 151 pages.
Pennington, Kelly Marie.
Experiments and models to understand gene flow from transgenic fish in different environments..
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