Mitochondrial mutations may decrease population viability

It is ironic that an organelle that is pivotal for the function of male gam etes is inherited by sons only from their mother. A recent study of human f ertility has provided the first definitive evidence that mitochondrial DNA mutations can reduce male fertility but with little or no effect on females , These results present the possibility that the viability of small populat ions might be reduced by increases in the frequency of mtDNA genotypes that lower the fitness of males.