Author(s): W M Muir, D Howard
Any release of transgenic organisms into nature is a concern because ecological relationships between genetically engi¬neered organisms and other organisms (including their wild-type conspecifics) are unknown. To address this concern, we developed a method to evaluate risk in which we input estimates of fitness pa¬rameters from a founder population into a recurrence model to predict changes in transgene frequency after a simulated transgenic release. With this method, we grouped various aspects of an organ¬ism's life cycle into six net fitness components: juvenile viability. adult viability, age at sexual maturity, female fecundity. male fertility. and mating advantage. We estimated these components for wild-type and transgenic individuals using the fish, Japanese medaka (Oryzia, !wiper). We generalized our model's predictions using various cont. binations of fitness component values in addition to our experi¬mentally derived estimates. Our model predicted that, for a wide range of parameter values, transgenes could spread in populations despite high juvenile viability costs if transgenes also have sufficiently high positive effects on other fitness components. Sensitivity analyses indicated that transgene effects on age at sexual maturity should have the greatest impact on transgene frequency. followed by juvenile viability, mating advantage, female fecundity, and male fertility, with changes in adult viability, resulting in the least impact.