Systematics Section / ASPT
Streit, Angela , Hufford, Larry , Webster, Michael .
Phylogeography of the Synthyris missurica complex (Veronicaceae/Scrophulariaceae) in the North American Pacific Northwest.
Synthyris missurica (including subspecies missurica, stellata and major) is a forest margin perennial in the Pacific Northwest (PNW). The species complex consists of three geographically disjunct groups that include populations in (1) the Columbia Gorge (west group), (2) northeastern California/south central Oregon (south group), and (3) western Idaho/eastern Washington/northeastern Oregon (east group). Fragmentation of once widespread populations caused by (1) drying of the Columbia Plateau after Miocene uplift of the Cascades and/or (2) dispersal from Pleistocene refugia are implicated in the origins of biogeographic complexity in the PNW. We used plastid haplotypes (psbA-trnH) to infer which processes may be responsible for the geographic distribution of populations. Ten individuals in each of thirteen populations throughout the range of S. missurica were examined. Twenty-seven of thirty-five total haplotypes were unique to individuals. One haplotype shared between the south and east groups was very common in the south; two haplotypes were shared between the east and west groups. A minimum spanning network revealed two common and widespread, but divergent haplotypes indicating a major split between south and east groups or among all three groups. Most genetic diversity is centered in the east, although the south group contains several unique haplotypes. Two populations sampled in the most geographically restricted west group consist of two different haplotypes. Populations in the Clearwater Mountains and other areas in Idaho and northeastern Oregon exhibit haplotype diversity, perhaps indicating refugia. Nested clade analysis inferred restricted gene flow/dispersal with some long-distance dispersal to low elevations in the Columbia Gorge. Restricted gene flow with isolation by distance was inferred between populations in northeastern Oregon and west-central Idaho. There is no clear correspondence between subspecies and haplotype structure in the complex. This complex may be too young for lineage sorting to have completed or it retains ancient, widespread haplotype diversity.
1 - Washington State University, School of Biological Sciences, P.O. Box 644236, Pullman, Washington, 99163, U.S.
Presentation Type: Paper
Location: Cottonwood A (Snowbird Center)
Date: Wednesday, August 4th, 2004
Time: 8:30 AM