Worldwide population genetics of reed canarygrass: Who s Invading? Andrew R Jakubowski Randall D Jackson Michael D Casler 1
Outline Brief introduction to reed canarygrass Describe hypotheses, objectives, & results European and Asian populations Early North American herbarium specimens Present-day North American populations Discussion and Conclusions 2
Introduction Cool-season grass native to North America, Europe, and Asia Planted for forage since early 1800 s Identified as a potential cellulosic biofuel feedstock Today, a dominant wetland invader >200,000 ha in Wisconsin 3
Origin of invasion Major hypotheses: Hybridization among formerly distinct Eurasian pops (Lavergne & Molofsky 2007) Cultivars are more aggressive than wild pops (Dore & McNeill 1980) Eurasian pops are more aggressive than native North American pops (Lavergne & Molofsky 2004) 4
Objectives Is there geographic structure in Europe and Asia? Does genetic analysis of herbarium specimens support a distinct native North American subpopulation? What is the geographic origin of present-day invasive populations in North America? Was there a genetic bottleneck during introduction of Eurasian populations into North America? 5
Objectives Is there geographic structure in Europe and Asia? Does genetic analysis of herbarium specimens support a distinct native North American subpopulation? What is the geographic origin of present-day invasive populations in North America? Was there a genetic bottleneck during introduction of Eurasian populations into North America? 6
Objectives Is there geographic structure in Europe and Asia? Does genetic analysis of herbarium specimens support a distinct native North American subpopulation? What is the geographic origin of present-day invasive populations in North America? Was there a genetic bottleneck during introduction of Eurasian populations into North America? 7
Objectives Is there geographic structure in Europe and Asia? Does genetic analysis of herbarium specimens support a distinct native North American subpopulation? What is the geographic origin of present-day invasive populations in North America? Was there a genetic bottleneck during introduction of Eurasian populations into North America? 8
Plant Collections Europe and Asia 84 wild accessions from Europe and Asia North America 40 herbarium specimens from North America 231 present-day North American populations 24 cultivars from Europe and North America P. caesia (6x) & P. aquatica (control) 9
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Genetic Analysis Genetic markers 15 short sequence repeats (SSR) Developed from P. canariensis (Li et al. 2011) Structure software Clusters subpopulations using MCMC Discriminant analysis of principal components (DAPC) Maximize separation between groups while minimizing variation within groups BIC used to determine # of subpops 11
Results Is there geographic structure in Europe and Asia? Does genetic analysis of herbarium specimens support a distinct native North American subpopulation? What is the geographic origin of present-day invasive populations in North America? Was there a genetic bottleneck during introduction of Eurasian populations into North America? 12
Little geographic structure in Europe & Asia 13
Minimal spatial autocorrelation in Europe & Asia 14
High within and among cultivar diversity 15
Results Is there geographic structure in Europe and Asia? Does genetic analysis of herbarium specimens support a distinct native North American subpopulation? What is the geographic origin of present-day invasive populations in North America? Was there a genetic bottleneck during introduction of Eurasian populations into North America? 16
Support for a distinct native North American subpopulation 17
Geographic distribution of native North American subpopulation 18
Results Is there geographic structure in Europe and Asia? Does genetic analysis of herbarium specimens support a distinct native North American subpopulation? What is the geographic origin of present-day invasive populations in North America? Was there a genetic bottleneck during introduction of Eurasian populations into North America? 19
Classification system for Eurasia and North America subpopulations 20
99% of present-day North American populations are of Eurasian origin 21
Location of present-day native North American populations 22
Location of present-day native North American populations 23
Results Is there geographic structure in Europe and Asia? Does genetic analysis of herbarium specimens support a distinct native North American subpopulation? What is the geographic origin of present-day invasive populations in North America? Was there a genetic bottleneck during introduction of Eurasian populations into North America? 24
All Eurasian population are present in North America with similar admixture 25
Invading populations are as diverse as Eurasian populations 26
Little geographic structure in either region 27
Revisit hypotheses of invasion Hybridization among formerly distinct Eurasian pops (Lavergne & Molofsky 2007) No, significant admixture present in Europe Likely due to use in agriculture since 1800 s Invasive pops look similar to Eurasian pop s 28
Revisit hypotheses of invasion (cont d) Cultivars are more aggressive than wild pops (Dore & McNeill 1980) Unlikely Doesn t seem to matter where in Eurasia the plants came from But, continuous introduction of Eurasian pops for forage, soil stabilization, phytoremediation, etc.? Cultivars no more productive or fecund than wild pops in wetlands (Jakubowski et al. 2011) 29
Revisit hypotheses of invasion (cont d) Eurasian pops are more aggressive than native North American (Lavergne & Molofsky 2004) Yes, but why? Differences in competitive ability? No evidence for increase in competitive ability after introduction (all Eurasian pops present) Better adapted to eutrophic wetlands? Analogous to the Phragmites story? Why no hybrids between the two regions? 30
Conclusions Native North American populations were present throughout the continent Eurasian populations have replaced native North American populations No genetic bottleneck Similar population structure in Eurasia and North America How should management be influenced? 31
Acknowledgements GLCI grant 941-3 RC Johnson & Jinguo Hu Hasan Khatib USDA-GRIN Aberystwyth University NordGen IHAR IPK Gatersleben University of Wisconsin Herbarium University of Alaska Museum of the North Bell Museum DAO Canada Iowa State Herbarium Universitѐ Laval Herbarium 32
Questions? Questions? 33