00:01
This question, we have flies and they have offspring.
00:06
In the ratio, there's 200 and two female flies.
00:11
And they only produce 98 males.
00:15
So normally we expect a one to one ratio for sex.
00:20
And so you should expect that if you have 200 females, that you have 200 males.
00:27
But this ratio here looks more like a two to one.
00:31
So there's two times as many females compared to males.
00:36
And so what this tells me is that there is a x -linked recessive allele that's hiding in the females.
00:52
And so she would have a genotype that looks like this, but with a normal phenotype.
00:58
So she would appear to be normal, but this little sneaky recessive allele is getting into the offspring and killing half of the males.
01:06
And so if we take this female, so say a female from the offspring, and we breed her with a normal male, what we would get, let's do a quick punant square so we can see what we're talking about here...