Test of a novel eradication method for a population of an invasive fish in a spring system in the Chihuahuan desert

Authors: Laura E. Dugan

Year: 2008 (xl)

Abstract

Invasive species are the second greatest threat to global biodiversity. Potential impacts from invasive species range from such ecological effects as competition with and predation of native species to genetic effects such as hybridization and outbreeding depression. They can also potentially bring novel diseases with them which can spread to native hosts. While the best method for dealing with an invasive species is prevention, this is often not possible. Amelioration methods that have been commonly used to manage invasive populations include physical removal, which is often time-consuming and labor intensive, and chemical removal and biocontrol, both of which may have major deleterious effects on non-target species. Eradication is often not a possibility when invasive populations have grown too large or cover too great an area, but is sometimes possible when the invasive population is discovered early before it has spread, in smaller populations, or for populations in more isolated geographic areas. A recent theory, coined the Trojan Y-chromosome theory of eradication (Gutierrez and Teem, 2006, J. Theor. Biol. 241: 333-341), states that for a population of an invasive fish species, the repeated introduction of feminized super-males (individuals with two YY chromosomes that have been feminized with diethylstilbestrol) over a period of time will cause the sex ratio to become so skewed towards males that there will not be a sufficient proportion of females to sustain the population, and thus the population will crash. This research explores the feasibility of application of this theory on a real system, the invasive West African jewel cichlid, Hemichromis guttatus, in the Cuatro Ciénegas valley in the Chihuahuan desert in Coahuila, México. It is hypothesized that this fish competes with the endemic Cuatro Ciénegas cichlid, Herichthys minckleyi, upon which it is hypothesized to have a negative impact. Whether this method is usable for a particular species depends upon the sex-determining mechanism of the invasive fish. Microarray analysis and amplified fragment length polymorphism (AFLP) methods are being employed to determine if Hemichromis has the appropriate sex-determination mechanism for application of this theoretical eradication method.