Maternal Inheritance of Mitochondria as a Constraint on Male Adaptation

Board Of Regents, Nshe, Obo University Of Nevada, Reno, Reno NV

Investigators

Abstract

Whereas nuclear genes are inherited from both parents, only females transmit mitochondrial DNA to offspring. Because males do not transmit mitochondria, heritability for mitochondrial-based differences in male survival and/or reproductive success is zero, precluding any direct evolutionary response to selection acting on mitochondrial mutations that either reduce or enhance male fitness. In this study, the arachnid, Cordylochernes scorpioides, will be used as a model system to investigate the effects of natural mitochondrial variation on the fertilization capacity of sperm. The research will encompass whole-mitochondrial genome sequencing, comprehensive analysis of physiological and morphological sperm characteristics important in fertilization success, an experiment designed to identify the target of selection acting on sperm traits, and a multi-generation study in which the evolutionary response to selection on sperm will be assessed using both maternally- and paternally-based selection regimes. Uniparental inheritance of mitochondria creates male/female asymmetries in response to selection that have profound implications for evolutionary processes ranging from male adaptation to population viability, sexual selection and speciation, as well as for human health and disease. Mitochondrial mutations, including nucleotide substitutions, deletions and insertions, are known to be a primary cause of low sperm count and poor sperm motility in humans. The proposed research thus provides an exciting context for engaging both educators and students in basic evolutionary research with far-reaching practical implications.