Male sterility promotes

Male sterility promotes Outbreeding.
The presence of male sterility leads to heterozygosity in a species as it promotes outbreeding and reduces homozygosity due to the elimination of inbreeding.
Male sterility results from the action of nuclear genes or cytoplasmic genes or both. Male sterility is caused due to pollen or anther abortion.
Outbreeding refers to matings between individuals from different populations, subspecies, or species. Outbreeding can result in a decline in reproductive fitness known as outbreeding depression, but this is less common than inbreeding depression.