McGlaughlin, Mitchell E , Wallace, Lisa Ellen , Helenurm, Kaius .
Lineage sorting and the interpretation of phylogeographic patterns in Lotus (Fabaceae) from the California Channel Islands.
The California Channel Islands represent a unique system to study insular plant evolution due to variability in island age, size, and separation, and the proximity of the entire island chain to the continental mainland. The geographic distribution of these islands affords the potential for recurrent colonization and gene flow from the mainland. However, the same factors that make these islands interesting also presents a substantial challenge due to the lack of genetic isolation from mainland populations and hence the potential for incomplete lineage sorting to obscure evolutionary relationships. The evolutionary diversity created by the California Channel Islands is exemplified in the island endemic taxa of the genus Lotus (Fabaceae). Lotus argophyllus consists of six varieties, three of which are endemic to the Channel Islands, and primarily occur on the drier southern islands. Lotus dendroideus consists of three varieties endemic to the Channel Islands, and primarily occur on the wetter northern islands. These species are close relatives and members of the same subgenus, but they are not believed to be sister taxa. This suggests that they two species have independently colonized the islands and should independently exhibit monophyly. Using chloroplast sequence data we aim to untangling the complex evolutionary history of this group in spite of ancestral polymorphism and incomplete lineage sorting. The chloroplast data indicates that two Lotus lineages have colonized the Channel Islands, one of which is composed solely of populations of L. argophyllus and one that includes members of both L. argophyllus and L. dendroideus. This suggests that there have been multiple dispersals events from the mainland and among islands.
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1 - University of South Dakota, Department of Biology, 414 E. Clark St, Vermillion, SD, 57069, USA
2 - Mississippi State University, Department of Biological Sciences, P. O. Box GY, Mississippi State, Mississippi, 39762
Presentation Type: Oral Paper:Papers for Topics
Location: Williford A/Hilton
Date: Tuesday, July 10th, 2007
Time: 3:45 PM