Research is being conducted on the evolution of sex-dependent mtDNA transmission in freshwater mussels. Some species, such as the semimytilus algosus, have been found to exhibit doubly uniparental inheritance of mitochondrial DNA, while others, like the brachidontes pharaonis, show no evidence of this phenomenon despite mitochondrial heteroplasmy. The study of mitochondrial epigenetics and mitogenomics in various bivalve species is providing new insights into this process.