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.
