Genetically-Engineered Death Carp

angkor writes "Kinda cool... Carp that produce only male offspring. They do something like this with sterile fruitflies as well."

Comments

Let's do the math

[geoswan]

Okay, let's play out your thought experiment.

There are complicating factors -- like the hangers on from previous generations that are still fertile, and that with fewer carp eggs are hatched maybe more of them will survive, since they won't have as many other carp to compete with. Let's ignore those factors, and, for the sake or argument, work with thought carp that only breed once.

Your assumptions were 250 normal females, 200 normal males, and 50 males with the daughterless gene, correct?

Generation 1, 40% female, 40% male, 20% daughterless males

Generation 2, 33% female, 33% male, 33% daughterless males

Generation 3, 25% female, 25% male, 50% daughterless males

Generation 4, 8% female, 16% male, 75% daughterless males

Generation 5, 2% female, 4% male, 93% daughterless males

And each generation from generation 2 on, since there are less females there are fewer eggs laid, and therefore fewer fish reaching maturity. Ignoring those factors I mentioned above generation 3 would be down a third to 333 adult fish, 81 of which would be female. Generation 4 would be 162 adult fish, with about a dozen females. Generation 5 would be about two dozen adult fish.

Okay, they only plan to introduce males with the daughterless gene representing less than 1% of the current population, during the first year.

I don't have the right tools to do the math for an addition of 1% per year of males with the daughterless gene. Maybe when I get home.