Why are zonkeys unable to produce fertile offspring, such as eggs or sperm?
The uneven chromosome count prevents the successful formation of viable gametes during meiosis.
The inability of a zonkey to reproduce stems directly from the mathematical disparity in chromosome sets inherited from its parents. The donkey provides 31 chromosomes, and the zebra provides either 22 or 23, resulting in an irregular total count (e.g., 53 or 54). During meiosis, the process required to create reproductive cells, chromosomes must pair up identically. Because the zonkey's chromosome set is uneven and irregular, the necessary alignment and separation do not occur correctly, meaning viable sperm or eggs cannot be formed. This sterility confirms that while zebras and donkeys are close enough within the *Equidae* family to cross, they have diverged into biologically distinct reproductive groups.
