What Prevents Horses And Donkeys From Hybridizing To Form A New Species?
a) reduced hybrid fertility
b) reduced hybrid viability
c) mechanical isolation
d) gametic isolation
e) behavioral isolation
thank you for the help
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A – reduced hybrid fertility
Horses have 64 chromosomes, while donkeys have 62. When horses and donkeys are mated, the mule offspring have 63 chromosomes. The gestation period in donkeys is 12 months on average, but it may vary from 11 to 14 months. Despite being considered sterile, mare mules and mare hinnies will have estrus cycles. These cycles can be regular, or erratic and variable. Female hinnies and mules can be used as embryo transfer recipients but care must be given to compatibility of donor and recipient. There have been documented cases of fertility in the female mule but not the female hinny (7). A report from Morocco indicates that a mule mare produced a foal with 62 chromosomes. The cells of the mule mare were a mosaic, some carrying 63 chromosomes while others carried 62.
The foal has 62 and is believed to be fathered by a donkey. This is the fourth female mule to be confirmed to be fertile (8).
Intact male donkeys and mules can be quite “stallion-like” or aggressive in behaviour. If they are not being used for breeding purposes or as a teaser, it is highly recommended that they be castrated. Castration must be performed by a veterinarian.
a. horse+ donkey=mule
mules can’t breed