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

小行星9623690 马里波萨百合和它们的亲戚（Calochortus）是北美西部最大和生态最多样化的植物属之一。 它们的花朵通常非常美丽，从开放的郁金香状花朵到华丽的点头球，再到花瓣内表面上有一层浓密的毛发的奇异形式。 大多数物种有狭窄的，不重叠的分布，在栖息地从沙漠到chapparal，针叶林，亚高山草甸。 有几个物种生长在蛇纹石、石膏或其他不寻常的基质上;许多物种现在已接近灭绝。 主要研究人员Givnish（主管）和Patterson（博士生）将通过从以前和新鲜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。 他们计划基于DNA序列推导出植物的分子家谱，确定基于DNA序列的树木与基于形态特征的树木之间的一致性，并确定彼此接近的物种是近亲还是远亲。 他们还将评估某些特征是否在马里波萨百合的家族史中出现过一次或多次;例如，可以在蛇纹土壤上生长的百合是否是密切相关的（该特征的一种外观，仅在第一种具有这种能力的植物的后代中表达）或远亲（该特征的多次外观）。 研究将集中在Calochortus的三个部分中的两个，合作者计划研究剩余的部分。 这些调查应该揭示西部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.