Dissertation Research: Molecular Evolution, Adaptive Radiation, and Geographic Diversification in Calochortus (Liliaceae)

9623690吉夫尼什马里波萨百合及其近亲(Calochortus)组成了北美西部最大和最具生态多样性的植物属之一。它们的花通常非常美丽，从开放的郁金香般的花朵，到艳丽的点头球状花朵，再到花瓣内表面覆盖着浓密毛发的奇怪形状。大多数物种具有狭窄的、不重叠的分布，分布在从沙漠到小岛屿、针叶林和亚高山草甸的生境中。有几个物种生长在蛇纹石、石膏或其他不寻常的基质上；许多物种现在濒临灭绝。首席研究员吉夫尼什(主管)和帕特森(博士生候选人)将通过从以前和新收集的标本中提取叶绿体和核DNA来评估马里波萨百合之间的关系。他们计划根据DNA序列推导出植物的分子谱系树，确定基于DNA序列的树和基于形态特征的树之间的一致性，并确定彼此生活得很近的物种是近亲还是远亲。他们还将评估某些性状在马里波萨百合的家族史上是否出现过一次或不止一次；例如，能够生长在蛇形土壤上的百合是否有密切的亲缘关系(一种性状，只在从第一次具有这种能力的植物中表现出来)或远缘关系(多次出现这种性状)。研究将集中在Calochortus的三个部分中的两个部分，合作者计划研究剩余的部分。这些调查应该能揭示WestOS最大、但消失最快的植物群之一的多样性背后的过程。

9623690 GIVNISH Mariposa lilies and their relatives (Calochortus) comprise one of the largest and most ecologically diverse plant genera in western North America. Their flowers are often strikingly beautiful and vary from open, tulip-like blossoms, to showy nodding globes, to bizarre forms with a dense layer of hairs over the inner surface of the petals. Most species have narrow, non-overlapping distributions, in habitats ranging from deserts to chapparal, coniferous forests, and subalpine meadows. Several species grow on serpentine, gypsum, or other unusual substrates; many are now close to extinction. Principal investigators Givnish (supervisor) and Patterson (doctoral candidate) will evaluate the relationships among Mariposa lilies by extracting chloroplast and nuclear DNA from previously- and freshly-collected specimens. They plan to derive a molecular family tree for the plants based on DNA sequences, determine the amount of agreement between trees based on DNA sequences and those based on morphological traits, and establish whether species that live in close proximity to each other are near or distant relatives. They will also assess whether certain traits have appeared once or more than once in the family history of Mariposa lilies; for instance, whether lilies that can grow on serpentine soils are closely related (one appearance of the trait, expressed only in plants descended from the first to have this ability) or distantly related (multiple appearances of the trait). Research will focus on two of the three sections of Calochortus, with collaborators planning to study the remaining section. The investigations should shed light on the processes underlying the diversity of one of the WestOs largest - but most rapidly disappearing - groups of plants.