Rausch, Joseph H. , Novak, Stephen J. .
Hierarchical analysis of quantitative genetic variation in Taeniatherum caput-medusae (Poaceae): life-history and morphometric trait variation among introduced populations.
Quantitative genetic research on invasive species, when combined with information on the history of introduction and monogenic trait variability, provides information on ecological and evolutionary processes associated with biological invasions (e.g. founder effects, genetic bottlenecks, selection). This study was undertaken to determine how quantitative trait variation is partitioned at various hierarchical levels in 12 populations of the annual, self-pollinating, invasive grass Taeniatherum caput-medusae. A nested analysis of phenotypic variation of 20 life-history and morphometric traits was performed with the following levels: among regions, among populations, among families, and within families. Results indicate that the majority of quantitative genetic variability was partitioned among regions or among populations. Significant differences among populations and among families were observed for all traits, and significant differences among regions were observed for 12 of the 20 traits. Quantitative genetic variability among populations (mean QST = 0.80) shows similar patterns as those obtained by allozyme (GST = 0.93) and RAPD (GST = 0.89) analysis. Comparing QST values of each trait to GST values generated from allozymes and RAPDs allows assessment of selectional pressures of traits among populations. Results suggest that the observed levels of quantitative genetic variability are due to multiple introductions, subsequent intra-regional spread, and local adaptation of ecologically significant traits (e.g. days to flowering) after establishment.
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1 - Washington State University, School of Biological Sciences, Po Box 644236, Pullman, Washington, 99164-4236, USA
2 - Department of Biology, Boise State University, 1910 University Drive, Boise, Idaho, 83725-1515, USA
Presentation Type: Oral Paper
Date: Monday, August 15th, 2005
Time: 2:00 PM