Maternal Inheritance of Mitochondria as a Constraint on Male Adaptation

虽然核基因是从父母双方继承的，但只有雌性将线粒体DNA传递给后代。由于男性不传递线粒体，基于线粒体的男性存活和/或生殖成功差异的遗传率为零，排除了对线粒体突变的选择的任何直接进化反应，线粒体突变降低或增强了男性的适合度。在这项研究中，将以蜘蛛纲天蝎为模型系统，研究自然线粒体变异对精子受精能力的影响。这项研究将包括全线粒体基因组测序，对受精成功至关重要的精子生理和形态特征的全面分析，旨在确定选择作用于精子特征的目标的实验，以及一项多代研究，其中将使用母系和父系两种选择制度评估对精子选择的进化反应。线粒体的单亲遗传造成了男性/女性对选择的反应不对称，这对从男性适应到种群生存、性选择和物种形成等进化过程以及对人类健康和疾病都具有深远的影响。线粒体突变，包括核苷酸替换、缺失和插入，已知是人类精子数量低和精子活力差的主要原因。因此，拟议的研究为教育工作者和学生提供了一个令人兴奋的背景，使他们参与具有深远实践意义的基础进化研究。

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.