| In this dissertation research I addressed several phylogeographic and population genetic questions, and their conservation implications for a long-lived perennial plant, Lilium philadelphicum L. (Wood Lily, Red Lily, or Prairie Lily). First, using chloroplast DNA sequences and a nested clade analysis, I inferred the minimum number of glacial refugia during the last glacial maximum and post-glacial migration patterns of L. philadelphicum in North America. The results suggest there were at least two glacial refugia, one located in the southeast, and one located on the east coast of the United States. Moreover, extant western and northwestern populations were most likely founded from populations in the southeast and Midwest, indicating a general southeast to northwest post-glacial migration pattern.; Second, using novel nuclear microsatellite loci that I developed, I assessed the potential effects of habitat alteration on gene flow between populations. I estimated the level of population differentiation and gene flow on local spatial scales on both natural and highly disturbed landscapes. On natural landscapes in the western U.S., I did not detect any genetic structure or isolation by distance, and high gene flow between patches. In contrast I found a low level of genetic structure and isolation by distance, and low levels of gene flow between patches on a highly urbanized Midwest landscape. My results suggest that fragmentation alone may not affect gene flow between patches and that genetic patterns may indicate panmixia on an undisturbed (yet fragmented) landscape. In contrast, gene flow may be reduced and population substructure may increase between fragmented patches distributed on a highly urbanized landscape. |
