Mating System Analysis of Native Populations of Taeniatherum caput-medusae (Medusahead): Potential for Post-Introduction Evolution During Biological Invasions

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Faculty Mentor Name

Stephen J. Novak

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Student Presentation


Taeniatherum caput-medusae (medusahead) is a highly invasive grass in the Western United States (U.S.). Using enzyme electrophoresis, I determined the mating system of native populations using two approaches: the Inbreeding Coefficient (F) method and progeny array analysis. These results were compared with data for invasive populations to determine whether an evolution of mating system is associated with this invasion. Previous data indicated that 10 invasive populations were 99.8% self-pollinating, with a 0.2% outcrossing rate. Both approaches I used were in agreement, and indicate that the 10 native populations I analyzed are 100.0% self-pollinating (and 0.0% outcrossing). These data indicate an extremely high self-pollination rate for both native and invasive populations, and do not suggest a mating system shift has occurred. Rather, high levels of self-pollination within native populations suggest that this highly selfing mating system may be a pre-adaptation contributing to the invasion of T. caput-medusae in the Western U.S.


This project was part of the Student Research Initiative (SRI) program in the summer of 2013 and was presented during the 3rd Annual Summer Undergraduate Research Conference at Boise State University.

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