TitleEvolutionary and demographic processes in the invasive weed Microstegium vimineum
NameNovy, Ari E. (author), Hartman, Jean Marie (chair), Bonos, Stacy (internal member), Struwe, Lena (internal member), Smouse, Peter E. (outside member), Rutgers University, Graduate School - New Brunswick,
Invasive plants--Molecular aspects,
DescriptionMicrostegium vimineum (Trin.) A. Camus (stiltgrass) is considered among the most invasive plants in the eastern United States. There has been considerable study of this species’ ecology and management though far less attention has been paid to its molecular ecology and the evolutionary processes which may influence its invasion success. Here, I describe a newly developed molecular marker system (microsatellite) which I used to examine M. vimineum’s genetic population structure and diversity in both its native and introduced ranges. I found clear signals that M. vimineum’s mating system is the most important determinant of the species’ population structure and variability. The invasive range had lower genetic diversity overall, probably due to founder effects. Also, population and regional genetic differentiation appeared to be ‘in process’ in the invasive range. Furthermore, M. vimineum’s mixed cleistogamous/chasmogamous mating system allowed for the near fixation of microsatellite genotypes in a given population by high rates of selfing, while still permitting the persistence of allelic diversity and generation of new genotypes at low frequency via occasional outcrossing. Thus, this mating system may confer adaptive advantage to the species as it settles upon fit genotypes in a given area while retaining evolutionary potential for range expansion into new habitats. I also attempted to discern adaptively significant phenotypes in M. vimineum through the measurement of phenological variation of plants originating from across the species’ invasive range under manipulated light treatments. Flowering time and biomass were both strongly correlated with the latitude of population origin such that populations collected from more northern latitudes flowered significantly earlier at lower biomass than populations from southern locations. This pattern suggests rapid adaptive evolution of phenology over a period of less than one hundred years, and such changes have likely promoted the northward range expansion of this species. Interestingly, barriers to gene flow, including bottlenecks and inbreeding, have apparently not forestalled adaptive processes for this plant. Based on literature review and these new data, I hypothesize that adaptive evolution of phenological traits may be widespread in many invasive plant species and an essential process during range expansion.
NoteIncludes bibliographical references
Noteby Ari E. Novy
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.