ASFB Home > 2003 > Biological Invasions: Consequences for Parasites, Pathogens, Emerging Diseases, and Fisheries in the Marine Environment.

The population genetics of Daughterless Carp

Dr Dean Gilligan

NSW Fisheries, Narrandera Fisheries Centre, Po Box 182, Narrandera NSW 2700
Email: Dean.Gilligan@fisheries.nsw.gov.au

Daughterless gene technology under development by CSIRO Marine Research, is believed to be a highly effective and novel way of controlling pest fish species such as carp. Release of genetically modified carp into wild populations is predicted to skew the sex ratio of the population, resulting in reduced productivity and eventual extinction. Because daughterless carp can have equivalent reproductive success to wild-type fish, the daughterless gene is predicted to escape natural selection, rapidly spreading through the wild population. However, previous attempts to use a populations own genes as bio-control agents in a range of species have failed. To date, models of the probable efficiency of daughterless gene technology have not addressed the fundamental issue of population genetic processes. A simple population genetics model was developed which models the frequency of daughterless phenotypes within a population and the impact of potential selection against daughterless carriers. This model suggests that extinction is inevitable if daughterless carriers are as fit as wild-type fish (similar mating success, recruitment success and survival to maturity). Further, the effectiveness of daughterless technology is extremely robust to stocking densities and effort. However, population extinction is unlikely if daughterless carriers are less fit than wild-type. Despite the low probability of extinction, a resultant stable skewed sex ratio may permanently reduce carp numbers.

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