Breeding. How does it happen

Roman

Geneticist
Staff member
#1
Well, we looked at all the genes of unicorns that was clarified in the genetic laboratory of the project to the current moment. It's time to discuss how unicorns mate for the offspring. According to the legends, when two unicorns love each other (well, or just like each other, it's much easier in this respect), they approach each other, touch the horn to the horn, a magnificent rainbow flashes (this is some kind of quantum effect, connected, most likely, with higher dimensions, but so far this is only my hypothesis), and a new unicorn appears. He is already an adult and ready for anything his parents can do.

Let's see how this happens. Our unicorns are diploid creatures, that is, each of them has double set of genes. You already had to understand this — each gene has two alleles, one dominant, and one recessive, and they are located on different chromosomes (it should be understood that on one chromosome are dominant values of some genes and recessive others — there is no dominant chromosome, as there is no recessive; of course, if it turns out that only the dominant values of all genes will be on one chromosome, then such a chromosome can be called «dominant», but it's pointless).

So. To obtain offspring, one chromosome is taken from each of the parents. This is an absolutely random process — just like the dice fall. Two chromosomes, one from each parent, constitute the genotype of the new unicorn. This genotype is further expressed in the phenotype in accordance with all previously described rules. What does it mean? Oh... This has very serious consequences when applied to physical characteristics and appearance. Let's look at the example of one gene, as it can be. Let breed two unicorns with the following values of the WNGFRM gene:
  • Parent 1: race = 0, WNGFRM = (12, 213). This means that his wings are straight.
  • Parent 2: race = 5, WNGFRM = (76, 34). This means that his wings are nimble.
What are the wings of the offspring? There are four inheritance possibilities (types of wings are indicated for the case if the descendant has inherited the race = 5, for the race = 0 everything has to be recalculated taking into account the shifts according to the preference for the wing form classifier):
  • Option 1: WNGFRM = (12, 76), the wings are nimble.
  • Option 2: WNGFRM = (12, 34), the wings are massive.
  • Option 3: WNGFRM = (213, 76), the wings are cute.
  • Option 4: WNGFRM = (213, 34), the wings are cute.
Thus, in four variants of the offspring, three variants of the wings can be obtained. Having set aside the process of expression of the descendant genes in a new phenotype, now we consider with the help of general formulas how any gene is inherited. Let the gene of parent 1 be equal to (x, X), and the same gene of parent 2 is (y, Y). By tradition, recessive alleles are denoted by lowercase letters, and dominant ones by uppercase. And also for the sake of definiteness x < y <Y < X, although this order does not affect the conclusions, we fix it for definiteness (other possible orders: x <y <X <Y and x <X <y <Y to within a shift roles of parents). Then there are four options:
  • (x, y), and y is manifested.
  • (x, Y), and Y is manifested.
  • (X, y), and X is manifested.
  • (X, Y), and X is manifested.
Thus, the weakest allele of the four parental alleles is never manifested (although it is inherited in half the cases), the second and third are manifested in 25 % of cases, and the strongest allele is manifested in half of the cases. And so for each gene. And it's great, because suddenly an offspring can display a phenotypic trait, which none of the parents had (for example, a grandmother or great-grandfather had).

So it goes.