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。其中一种比较不寻常的变异是接合，即两个或更多的精子在头部结合形成一个单一的功能单位。接合通常被解释为对精子竞争的适应，并独立地出现在不同的群体中，如负鼠、蜗牛和潜水甲虫。这项研究考察了精子结合的进化途径和健康后果。研究人员将使用行为观察、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)检验结合提供杀精环境保护的假说，以及(Iii)量化精子长度和结合大小对精子活力的影响，这是受精成功的一个重要相关因素。这个研究项目的智力价值包括它可能揭示精子形状和功能之间的关系，并提高对精子选择环境的理解，这是性别选择中被严重忽视的一个方面。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。产生的数据将被提交到公共数据库，以便于研究，在项目过程中收集的标本将被保存在博物馆收藏品中(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).