Reproductive isolation from a cross between a horse and a donkey or between a mare and a donkey, respectively. These animals are nearly always sterile due to the difference in the number of chromosomes between the two parent species. Both horses and donkeys belong to the genus "Equus", but "Equus caballus" has 64 chromosomes, while "Equus asinus" only has 62. A cross will produce offspring (mule or hinny) with 63 chromosomes, that will not form pairs, which means that they do not divide in a balanced manner during meiosis. In the wild, the horses and donkeys ignore each other and do not
Equus (comics) been captured in the same story. Equus reappeared under Mr. Orr's command in "Countdown" #36 (2007), clashing with Karate Kid and Triplicate Girl. After receiving a beating from Karate Kid, Equus was enraged that Mr. Orr, under Desaad's orders, would let them go. Equus severs the railroad tracks on which Karate Kid and Triplicate Girl's train is traveling, after having phoned the police, telling them that the derailment is a metahuman attack, and that the metahumans themselves are bio-weapons, leading the officers to shoot first and not ask questions. Karate Kid and Una eventually are able to beat Equus, disabling