Molecular evolution and ecological adaptation of male- and female-transmitted mtDNA genomes in bivalves

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My long-term objectives are to understand the origin and factors maintaining a highly unusual system of mitochondrial DNA inheritance present in bivalve mollusks. This system is called “doubly uniparental inheritance” (DUI) of mitochondrial DNA. Unlike all other animals, many groups of bivalves possess two distinct sex-associated mtDNA lineages rather than just a single, female-transmitted mtDNA lineage. My short-term objectives are to test various hypotheses that have been proposed to explain factors associated with the developmental controls and evolutionary dynamics of the male- and female-transmitted DNA genomes. These hypotheses include the proposal that DUI allows for natural selection to improve sperm performance in these mussels, or that these gender-associated genomes might play a role in sex determination. The distinct male and female transmitted mtDNA genomes found in marine mussels also undergo recombination, a phenomenon that was, until recently, not thought to occur in animal mtDNA genomes. My approach to studying this unusual system of mitochondrial DNA inheritance includes a combination of sperm motility analyses, whole mitochondrial genome sequencing assays, and bioinformatics/in silico analyses. The anticipated outcome of my research is to advance our understanding of basic biological processes, primarily in bivalves, but this knowledge will also apply to other animal groups. My research will advance our understanding of fundamental cellular processes and will be of general interest and value to geneticists, invertebrate biologists and zoologists. The advancement of pure knowledge in the area of sex determination in bivalves may have applications in the field of aquaculture and in the development of biological controls for invasive freshwater mussel species through artificial control of sex ratios. My research also has broad implications for interpreting the evolution of mitochondrial DNA. For example, my research program will provide essential data for interpreting DNA sequences for a particular gene known as Cox1, which is used as the basis of the "Consortium for the Barcode of Life" initiative. This is an attempt to use DNA sequence data to identify all species of animals in the world using a simple, inexpensive test. The correct interpretation of DNA Barcodes of native marine and freshwater mussels will be increasingly important as these species face threats from global climate change and global transport of invasive bivalve species.