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Abstract Detail


Molecular Ecology and Evolution

Meimberg, Harald [1], Rice, Kevin [2], McKay, John [1].

Multiple introductions and selection as facilitators of plant invasions: Barbed goatgrass invasions of serpentine soils in California.

The capacity of invasive plants to spread into new habitats despite extreme genetic bottlenecks during introduction is difficult to explain. Reductions in additive genetic variance should reduce the capacity of introduced species to adapt to new environments and expand their range. Multiple introduction of a species remains the most obvious mechanism to reduce the severity of a bottleneck. When two or more genotypes are introduced, there is a potential for recombination to generate heritable variation in ecological traits for selection to act upon. There are an increasing number of examples where invasive species show evidence for multiple introductions that interbreed after introduction. However, it remains untested whether this increased genetic variability is the cause for the invasiveness, or if recombination occurred after the lineages became established in their new range.
We conducted a comparative study in Aegilops triuncialis (barbed goatgrass) between invasive populations in California and accessions from its native range in Eurasia. Barbed goatgrass is currently invading serpentine soil outcrops in California and represents a serious threat to serpentine endemic plant communities. Using microsatellite polymorphisms we identified three independently introduced lineages in California with no detectable introgression among introduced lineages. All three lineages exhibited higher fitness on serpentine soil than on loam soil within a reciprocal sowing experiment on the two soil types. For each lineage this increase in fitness involves different sets of traits, suggesting independent evolution of serpentine tolerance. Eurasian genotypes showed a high variability in the traits we measured but only a few accessions exhibited increased fitness on serpentine soil. These findings support the hypothesis that either selection on pre-adapted genotypes or independent, parallel adaptation of three invasive lineages occurred during the invasion of Ae. triuncialis in California, with no evidence for the role of recombination among these multiple introductions.


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1 - Colorado State University, Bioagricultural Sciences and Pest Management, Plant Sciences Bldg., University Ave. 307, Fort Collins, co, 80523, usa
2 - University of California Davis, Department of Agronomy And Range Science, One Shields Avenue, Davis, California, 95616-8515, USA

Keywords:
Multiple introduction
Selection
adaptation
Aegilops triuncialis.

Presentation Type: Oral Paper:Papers for Topics
Session: CP41
Location: Boulevard B/Hilton
Date: Wednesday, July 11th, 2007
Time: 8:00 AM
Number: CP41001
Abstract ID:1252


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