Doubly Uniparental Inheritance and beyond: The contribution of the Manila clam Ruditapes philippinarum

The Manila clam, Ruditapes philippinarum (Adams & Reeve, 1850), is a widespread and commercially important bivalve species showing a peculiar way of mitochondrial inheritance known as Doubly Uniparental Inheritance (DUI), which is different from the strict maternal inheritance found in the broad majority of metazoans. DUI in R. philippinarum was discovered later than in mytilids and unionids. Nevertheless, this case keeps providing interesting data pertinent to the mechanism of this inheritance system. In this review, we discuss the contribution of this species, both in the context of the available knowledge on DUI and in the broader context of metazoan mitochondrial biology. Indeed, thanks to its unusual features, DUI can shed light on mitochondrial inheritance and biogenesis and, above all, on the relationship between mitochondria and germ line. Moreover, DUI is a unique experimental system for studying mitochondrial heteroplasmy, and two processes that shape genome evolution: genomic conflicts and mito-nuclear coevolution, which are at the very root of eukaryotic life.