In rabbit, white coat color is recessive in relation to gray, and wavy coat dominates over smooth coat.
In rabbit, white coat color is recessive in relation to gray, and wavy coat dominates over smooth coat. A gray wavy rabbit is crossed with a gray smooth-haired female. The offspring are half white wavy rabbits. How to cross further in order to get more white wavy rabbits? How to test the cleanliness of a first generation white wavy rabbit line.
Let’s designate the gene for white color of rabbit fur as in, then the gene for gray color of rabbit fur will be designated as B. Let’s designate the gene for wavy rabbit hair as C, then the gene for smooth wool will be c.
Since white rabbits with the cc genotype were obtained in the offspring, a conclusion should be drawn about the heterozygosity of the parent individuals for coat color – Bb.
The gray smooth-haired rabbit will be ВвСС, she will produce eggs Вс and bс.
Wavy cubs will be heterozygous for coat structure because they can only get the smooth coat gene from a rabbit. Thus, white wavy rabbits are bbСс.
To get more wavy white rabbits, you should cross the resulting rabbits when they reach puberty with each other. Given the heterozygosity of their genotype for the second trait, some of the F2 offspring will nevertheless have smooth hair.
Rabbits bCc obtained in F1 produce bC and bc germ cells.
F2 offspring from such rabbits will be represented by the following options:
white rabbits with wavy hair (bbcc) – 25%;
white rabbits with wavy hair, heterozygous for the second trait (2 bbСс) – 50%;
white rabbits with smooth hair (bbcc) – 25%.
Thus, 75% of F2 offspring will have white wavy hair.
In order to check the purity of the F1 rabbit line, one should resort to the method of analyzing crossing – crossing these BBC rabbits with white smooth BBC rabbits producing the same type of sex cells.
The offspring will look like:
white rabbits with wavy hair (bbСс) – 50%;
white rabbits with smooth hair (bbcc) – 50%.
The resulting cleavage indicates that the F1 rabbits are not purebred.
Purebred rabbits are homozygous. For example, bbCC (gametes of the same type – bC) obtained in F2, when crossed with bbcc rabbits, will not split in the offspring, which will be 100% uniform – bbCc, and have white wavy hair.
