Jacobs, Bridget , Willyard, Ann , Wallace, Lisa Ellen , Nepokroeff, Molly .
Population genetic analysis and chloroplast capture in Schiedea stellarioides and Schiedea spergulina.
The genus Schiedea (Caryophyllaceae) represents an adaptive radiation of 32 extant species that are endemic to Hawaii. Schiedea species exhibit a wide range of morphologies, breeding systems, and habitats making this an excellent model group for understanding insular evolution, including shifts to different breeding systems in plants. Recent nuclear genealogies inferred for Schiedea conflict with chloroplast histories and suggest past reticulate evolution. Recent phylogenetic studies suggests that an ancestor of Schiedea spergulina from Oahu colonized Kauai and captured the chloroplast genome of a congener lineage (S. stellarioides) already on Kauai, but retained its own nuclear genome. We examine the population structure of both rare species using nuclear microsatellites, and evaluate chloroplast haplotype polymorphism in naturally occurring populations of both S. spergulina and S. stellarioides. Levels of genetic variation in microsatellite loci are consistent with a past population bottleneck in S. stellarioides, which had been thought to be extinct, but was rediscovered on Kauai recently. PCA analyses of microsatellite data indicate that the Lawai Valley population of S. spergulina is well differentiated from other populations of that species on Kauai, which may support previous classifications recognizing the Lawai population as separate variety. The Lawai population of S. spergulina has a distinct chloroplast haplotype from populations of S. spergulina found in Waimea Canyon. This result was unexpected because Waimea Canyon populations are in close proximity to S. stellarioides populations inland, whereas the Lawai population is more distantly located near the coast. However, suitable habitat for either species is extremely fragmented and represents only a fraction of the estimated potential range for either species, based on habitat suitability models. Potential ranges might have been much more extensive and could have overlapped significantly before human occupation of Kauai.
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1 - University of South Dakota, Department of Biology, 414 East Clark Street, Vermillion, South Dakota, 57069, USA
2 - The University of South Dakota, Biology, 414 E. Clark St., Vermillion, SD, 57069, USA
3 - Mississippi State University, Department of Biological Sciences, P. O. Box GY, Mississippi State, Mississippi, 39762
Presentation Type: Poster:Posters for Topics
Location: Event Tent/Cliff Lodge
Date: Monday, July 27th, 2009
Time: 5:30 PM