How many fish does it take for guppies to invasively breed its way into dominating an ecosystem?
Biologists at the University of St. Andrews and the University of the West Indies did the experiment and came up with the startling number: just 1 female guppy.
Dr. Deacon explained, “Usually only one or a few fish are released. We know that the vast majority of species introduced to a new habitat in this way are unable to survive, let alone establish a population, which left us with a huge question mark.”
To try to solve the mystery, the researchers conducted a simple experiment, in which single wild female guppies were placed into outdoor tanks. After two years, they discovered that almost all of the tanks contained populations of guppies, each founded by just one female.
Dr. Deacon explained how the finding might explain the guppy’s success as an invasive species, “Sperm storage is an excellent adaptation for living in constantly changing habitats, and it might also explain the guppies’ global success. Female guppies can store sperm in their reproductive tracts for many months after mating, and this enables single fish to establish populations, even when no males are present.