Dissertation Research: The Slipper Orchids: Molecular, Morphological, and Ontogenetic Insights into the Evolution of Constrained Floral Diversity

在兰科(兰科)巨大的花卉多样性中，拖鞋兰属(塞浦路斯亚科)的四个属作为一个很容易定义的组合脱颖而出。它们千篇一律的花朵适合于通过暂时将昆虫困在猪笼状的嘴唇上进行授粉，然而，它们表现出了吸引各种传粉者的二级花朵修饰。由于拖鞋兰花的花部分在功能上是如此相似，只有形状和颜色可以作为建立基于花的关系的标准。植物体本身的结构并没有提供更多的数据，关于这一主题的最新工作可以追溯到1966年。叶绿体DNA分析已被证明有助于解决其他兰科植物和植物群之间的关系，将被应用于拖鞋兰花，希望揭示可用于更可靠地评估关系的众多特征(DNA突变)。叶绿体DNA与编码植物和花发育的染色体DNA分开存在，因此它应该是一个很好的内部关系指示器，在一个刻板的兰科植物群体中，这种外部特征很难定义，也很难相互联系。植物和花部分的特征将根据叶绿体DNA分析发现的关系进行研究，以期更多地了解它们的进化。还将研究植物的其他特征，以与分子作品进行比较，包括种子壁的外部雕刻。在研究拖鞋兰花的进化关系之后，我们将追溯它们的地理历史。拖鞋兰花表现出一种不寻常的分布，目前还没有对这种排列进行正式的研究。这项研究无疑将得到有关植物遗传关系(通过叶绿体DNA)的知识的帮助。塞浦路斯亚科没有化石记录，人们希望通过研究过去大陆运动的现代分布，可以获得它们起源的大致时间和地点。这项研究的另一个目的是试图了解一种进化机制，这可能是拖鞋兰花中出现的一些多样性的原因。在植物发育过程中发生的事件时间的变化可能会对植物和花部分的最终形状和大小产生严重的影响。两种相似的墨西哥拖鞋兰花的系统将被研究这种变化。一个物种似乎是另一个物种的幼年版本；这一假设将通过比较两个物种的花蕾和开放的花的部分的形状以及两种花的相对生长速度来检验。

Among the vast floral diversity of the orchid family (Orchidaceae), the four genera of the slipper orchids (subfamily Cypripedioideae) stand out as an easily defined assemblage. Their stereotyped flowers, adapted for pollination by temporarily trapping insects in their pitcher-like lips, nevertheless exhibit a secondary level of floral modifications attractive to a wide variety of pollinators. Because the floral parts of slipper orchids are so similar for functional reasons, only shape and color become available as criteria for establishing relationships based on flowers. Structure of the plant body itself offers little more data, the most recent work on this subject dating to 1966. Chloroplast DNA analysis, which has proven helpful in resolving relationships in other orchids and plant groups, will be applied to the slipper orchids in hopes of uncovering numerous characters (mutations in the DNA) that can be used to assess relationships more reliably. Chloroplast DNA exists separate from the chromosomal DNA that codes for plant and flower development, so it should serve as an excellent internal indicator of relationships in a stereotyped orchid group for which such external features are difficult to define and relate to one another. Characters of the plant and flower parts will be studied relative to the relationships uncovered with chloroplast DNA analysis in hopes of understanding more about their evolution. Additional features of the plants will also be examined for comparison to the molecular work, including external sculpturing of the seed walls. Following the work on evolutionary relationships of the slipper orchids, their geographic history will be traced. The slipper orchids display an unusual distribution, and no formal studies of this arrangement have yet been undertaken. This research will no doubt be aided by knowledge of the genetic relationships (by chloroplast DNA) of the plants in question. No fossil record exists for the Cypripedioideae, and it is hoped that by studying current distributions with respect to past continental movements, an approximate time and place of their origin may be obtained. An additional aim of this study will be an attempt to understand an evolutionary mechanism that may be responsible for some of the diversity seen in the slipper orchids. Changes in the timing of events that occur during the development of a plant can have drastic consequences for the final shape and size of both plant and floral parts. A system of two similar species of Mexican slipper orchids will be studied for such changes. One species appears to be a juvenile version of the other; this hypothesis will be tested by comparing shapes of flower parts in buds and open flowers of both species and by comparing the relative rates of growth of the two flowers.