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
Phrynobatrachus africanus Throat is dark grey in males but spotted with brown in females. "Phrynobatrachus africanus" occurs in lowland swampy forests. It can survive in somewhat degraded forests, but not in open habitats outside forest. Males call from cavities and holes near streams. Breeding takes place in pools with standing water along streams. It is a very common species. It can be negatively affected by loss of its forest habitat caused by logging, agricultural encroachment, and human settlements. It occurs in several protected areas. Phrynobatrachus africanus Phrynobatrachus africanus (common name: African swamp frog) is a species of frog in the family Phrynobatrachidae.