Dissertation Research: Maintenance of a Color-pattern Polymorphism in Green Swordtails, Xiphophorus helleri: Natural and Sexual Selection

动物和植物物种在许多特征上都有显著的差异，例如雪雁的身体颜色和牵牛花的花瓣颜色。生物学中的一个基本问题是如何在野生种群中保持遗传变异。剑鱼属的许多物种都表现出统一的灰色形态，以及具有不同黑色色素图案的形态；这种变异具有简单的遗传基础。在这项研究中，罗斯玛丽·格兰特博士和克里斯蒂安·迈耶通过对自然种群的实地调查以及对配偶选择、捕食和依赖季节的能见度的相互作用的实验室实验，研究了斑点和灰色形态在黑纹伊蚊中的维持。X.helleri是一个合适的模型系统，因为这些鱼很容易在实验室繁殖，也可以在它们自然栖息地的清澈、浅水中进行研究。剑尾鱼的颜色模式在生物体的外部特征和潜在的遗传机制之间提供了有形的联系，并提供了一个易于处理的系统来探索基本的生物现象。该项目将在伯利兹和新泽西州对非专业人员、年级学生和大学生进行研究的理论和实践方面的教育，并培训研究助理。

Animal and plant species are remarkably variable in many characters, e.g., body coloration in snow geese and petal color in morning glories. A fundamental question in biology is how genetic variation is maintained in wild populations. Many species in the fish genus Xiphophorus show uniformly gray forms as well as forms with different black pigment patterns; this variation has a simple genetic basis. In this study Dr. Rosemary Grant and Christiane Meyer investigate the maintenance of spotted and gray forms in X. helleri with field surveys of natural populations as well as laboratory experiments testing hypotheses on the interplay of mate choice, predation, and season-dependent visibility. X. helleri is a suitable model system because these fish are easily bred in the laboratory and can also be studied in the clear, shallow waters of their natural habitat.The color pattern in Xiphophorus provides a tangible link between the external characteristics of an organism and their underlying genetic mechanisms, and furnishes a tractable system with which to explore fundamental biological phenomena. This project will educate laypersons, grade schoolers and college students in theoretical and practical aspects of the research and train research assistants, both in Belize and New Jersey.