DISSERTATION RESEARCH: Evolution of Sperm Conjugation

精子具有巨大的多样性，但人们对精子形态变异的进化意义知之甚少。一种更不寻常的变异是接合，即两个或多个精子在头部结合形成一个功能单元。接合通常被解释为对精子竞争的适应，并且在负鼠、蜗牛和潜水甲虫等不同群体中独立出现。这项研究探讨了精子结合的进化途径和适应性后果。 研究人员将利用行为观察、生物化学和细胞学来（i）比较有和没有精子结合的物种中精子竞争的强度，（ii）检验结合提供保护免受杀精环境影响的假设，以及（iii）量化精子长度和结合物大小对活力的影响，这是受精成功的重要相关因素。该研究项目的智力价值包括它有可能揭示精子形式和功能之间的关系，并提高对精子选择性环境的理解，这极大地促进了对精子选择性环境的理解。性选择中被忽视的一个方面。该项目将为博士生提供培训，并为本科生提供宝贵的实验室和实地研究机会。 结果数据将提交给公共数据库以促进研究，项目过程中收集的标本将存放在博物馆藏品中（例如 NMNH）。

Sperm have tremendous diversity, but the evolutionary significance of variation in sperm form is poorly understood. One of the more unusual kinds of variation is conjugation, where two or more sperm join at the head to form a single functional unit. Conjugation is commonly interpreted as an adaptation to sperm competition and has independently arisen in groups as diverse as opossums, snails, and diving beetles. This study examines the evolutionary pathways and fitness consequences of sperm conjugation. The researchers will use behavioral observations, biochemistry, and cytology to (i) compare the intensity of sperm competition in species with and without sperm conjugation, (ii) test the hypothesis that conjugation provides protection from spermicidal environments, and (iii) quantify the effects of sperm length and conjugate size on motility, an important correlate of fertilization success.The intellectual merit of this research program includes its potential to reveal the relationship between sperm form and function and to improve understanding of the selective environment of sperm, a greatly neglected aspect of sexual selection. This project will provide training for a PhD student and valuable laboratory and field-based research opportunities for undergraduates. Resultant data will be submitted to public databases to facilitate research, and specimens collected during the course of the project will be deposited in museum collections (e.g. NMNH).