While most of the time eukaryotes get their mitochondrial genome from their female parent, the presence of paternal mitochondrial DNA has been occasionally reported, especially in hybrids. But leakage of this DNA during fertilization is often considered a failure of the mechanisms that normally ensure that solely the maternal mitochondrial genetic information gets transmitted to the offspring.
For example, in some species, mitochondria in sperm have a molecular tag that’s recognized by the fertilized egg, which then proceeds to degrade the unwanted genome. In hybrids, where the differences between the two mates are larger than those between a pair from the same species, research suggests that recognition process may not be as effective. This could increase the chances for the male’s mitochondrial DNA (mtDNA) to escape destruction and survive in the newborn.
However, recent theoretical and experimental studies suggest that this failure may not always be maladaptive. Hybrids, for instance, ...
