Dissertation Research: Maintenance of a Leaf Shape Polymorphism in Ipomoea Hederacea

紫薇牵牛花（Ipomoea hederacea）的自然种群含有两种不同的叶子形状：一些植物的叶子有三个裂片，而另一些植物的叶子没有裂片。这种程度的叶形差异已被证明会影响叶温调节（叶状叶更有效地散热）和食草动物偏好（一些昆虫利用叶形来识别可食用植物）。然而，叶片形状变化对田间植物性能的影响从未得到证实。对该植物的初步野外观察结果表明，分叶植物和无分叶植物在不同的环境条件下具有特异性。该研究将使用大规模的田间试验来量化植物在自然环境中叶片形状的功能。本研究还将利用温室实验对相关环境因子进行精确控制。这种方法可以确定叶片形状对植物性能的影响；可以解释这种奇特的多态性是如何维持的；并可能提供一些关于叶子形状对植物在不同环境中生存的重要性的见解。

9624051 Rausher Natural populations of the ivyleaf morning glory (Ipomoea hederacea) contain two distinct leaf shapes: some plants possess leaves with three lobes, while others possess unlobed leaves. Leaf shape differences of this magnitude have been shown to affect leaf temperature regulation (lobed leaves dissipate heat more effectively), and herbivore preference (some insects use leaf shape to recognize edible plants). However, an affect of leaf shape variation on plant performance in the field has never been demonstrated. Preliminary results from field observations of this plant species suggest that lobed and unlobed plants are specialized for different environmental conditions. The study will use large scale field experiments to quantify plant performance as a function of leaf shape in a natural setting. The study will also use greenhouse experiments to precisely control relevant environmental factors. This approach allows the determination of the effect of leaf shape on plant performance; may lead to an explanation of how this peculiar polymorphism is maintained; and may provide some insights into the importance of leaf shape for survival of plants in different environments.