Okay fish followers; get ready for a quick lesson in genetics! Selective breeding is the process of breeding for specific genetic traits. The percentage of progeny (offspring) with the wanted traits depends upon the traits fo the parents. This information is true in all organisms, but I'm going to explain it in terms of our goldfish. Offspring receive two copies of the same gene, one from the mother and one from the father, which determines any and every aspect of their life. I'm going to focus on the genes that determined the color of the first gold carps now called goldfish. The normal color is a dominant trait, meaning that the presence or absence of this trait ultimately determines the color of the fish. The gold color is a recessive trait, meaning that both parents need a copy of the trait in order for some of the offspring to be gold, otherwise, if the offspring has one copy of the dominant trait and one copy of the recessive trait the dominant trait will hide the recessive trait and the fish will be the normal color.
In this case both parents have one dominant and one recessive trait. Therefore 1/4 of the offspring will be gold and the rest will be normal colored
For those visual learners out there I'm going to also use what's called a Punnet square to explain this. A Punnet square is simply a way of determining all the possible genetic traits of the offspring using the traits in the parents. I'm going to call the dominant trait G (for gray) and the recessive trait g (for gold). Remember, the dominant trait is the normal color and the recessive trait is the new gold color.
In this case one parent has two dominant traits and the other parent has one dominant and one recessive trait. Therefore all of the offspring will be the normal color because all of the offspring have received a dominant trait from either one or both parents.
In this case one parent has two dominant traits and the other parent has one dominant and one recessive trait. Therefore all of the offspring will be the normal color because all of the offspring have received a dominant trait from either one or both parents.
In this case both parents have one dominant and one recessive trait. Therefore 1/4 of the offspring will be gold and the rest will be normal colored In this case one parent has one dominant and one recessive trait, and the other parent has both recessive traits. Therefore 1/2 of the offspring will be gold and the other 1/2 will be normal colored.
Furthermore in theory, if both parents had two dominant traits then all of their offspring would be normal colored, and if both parents had two recessive traits then all of their offspring would be gold. Pretty amazing, huh? And this is just scratching the surface! Just think of all the different varieties of goldfish there are! Mutations occur not only in color but also in size, shape, absence or presence of fins, location of eyes, shininess, etc. And once a mutation occurs, selective breeding to continue that mutation can begin.
Stay tuned for the next fish blog entry...we'll use our knowledge of genetics to try and solve who the parents of our own baby goldfish are!
Laramie
Stay tuned for the next fish blog entry...we'll use our knowledge of genetics to try and solve who the parents of our own baby goldfish are!
Laramie
Life Science Assistant
"Resident Fish Expert"
