Maternal Inheritance of Mitochondria as a Constraint on Male Adaptation

虽然细胞核基因从父母双方遗传，但只有雌性会将线粒体DNA传给后代。由于雄性不传递线粒体，基于线粒体的雄性生存和/或繁殖成功差异的遗传力为零，排除了任何直接的进化反应，即选择作用于线粒体突变，从而降低或增强雄性适应性。本研究将以蜘蛛Cordylochernes scorpioides为模型系统，研究天然线粒体变异对精子受精能力的影响。该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综合分析、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，其中将使用基于母亲和父亲的选择制度来评估精子选择的进化反应。线粒体的单代遗传产生了雄性/雌性不对称，这对从雄性适应到种群生存能力、性选择和物种形成以及人类健康和疾病等进化过程具有深远的影响。线粒体突变，包括核苷酸替换、缺失和插入，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参与具有深远实际意义的基础进化研究提供了一个令人兴奋的背景。

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.