How does the chromosome count disparity between the Plains zebra and the domestic donkey lead to Zonkey infertility?

The resulting odd number (around 53) causes severe complications during meiosis, preventing balanced gamete formation.

The biological inability of Zonkeys to establish self-sustaining populations is fundamentally rooted in their differing chromosome counts. A Plains zebra typically has 44 chromosomes, while a domestic donkey possesses 62 chromosomes. When these combine, the Zonkey inherits an approximate total of 53 chromosomes, which is an uneven or odd number. This imbalance presents a critical failure point during meiosis, the specialized cell division process required to produce reproductive cells, known as gametes. Because 53 cannot be divided evenly into balanced haploid sets, the resulting cells lack the necessary genetic structure to produce viable offspring, rendering the Zonkey infertile. This genetic hurdle is a common characteristic among most equid hybrids.