Mcglaughlin, Mitchell , Bresowar, Gerald , Helenurm, Kaius , Wallace, Lisa .
Isolation among islands as a driver of divergence in the endemic Lotus (Fabaceae) of 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 evolutionary diversity created by the California Channel Islands is exemplified in the island endemic taxa of the genus Lotus (Fabaceae). Lotus argophyllus consists of five 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. Both species are close relatives and are members of the same subgenus, but they are not sister taxa. Based on morphology, the two species are believed to have independently colonized the islands and should independently exhibit monophyly. Population level sampling of sequence data from the low copy nuclear region Adh-A has been used to examine the evolutionary history of the island taxa and close relatives that occur on the mainland. Of the sampled island taxa, neither L. argophyllus or L. dendroideus are monophyletic. Despite clear morphological differences, evolutionary history appears to be determined by island of occurrence, not taxonomic designation. In general, varieties were found to be monophyletic within islands or among adjacent islands, but when two or more varieties occuron a single island, they tend to have a sister relationship. Interestingly, L. argophyllus var. niveus, which is endemic to Santa Cruz Island, was found to be very distinct from other island Lotus taxa,showing a strong affinity to the mainland L. heermanii. Overall, this research illustrates how genetic data can resolve evolutionary histories that are significantly different than those inferred from morphology.
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1 - University of Northern Colorado, Biology, 501 20th St, Greeley, CO, 80639, USA
2 - University Of Northern Colorado, 501 20th Street, Greeley, CO, 80639, USA
3 - University Of South Dakota, Department Of Biology, Vermillion, SD, 57069, USA
4 - Mississippi State University, Biological Sciences, 295 Lee Blvd., Mississippi State, MS, 39762, USA
California Channel Islands
single copy nuclear gene
Presentation Type: Oral Paper:Papers for Topics
Location: Portland Room/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 10:15 AM