EVOLUTION AND SPREAD OF HERBICIDE RESISTANCE IN AGRICULTURAL WEEDS

One of the most challenging and costly problems facing agriculture today is the evolution of resistance to herbicides in cropland weeds.  Herbicides revolutionized agricultural production by markedly reducing human labor requirements and increasing crop yields and yield stability but their widespread and repeated use has selected for the evolution of resistance.  Research in my laboratory focuses on elucidating the processes underlying the evolution and spread of herbicide resistance in cropland weeds.  Current projects include:

• Assessing the abundance and distribution of glyphosate-resistant weeds
• Determining the genetic basis of glyphosate resistance
• Elucidating rates of resistance evolution associated with varying management practices
• Identifying pathways and mechanisms of resistance spread across the agricultural landscape

ESCAPE, ESTABLISHMENT AND SPREAD OF INVASIVE PLANTS WITH HORTICULTURAL ORIGINS

A major pathway of deliberate introduction of invasive plants to new geographical areas is the horticultural trade.  Worldwide, many invasive weeds have horticultural origins.  In California, more than half of the 78 most invasive weeds of natural areas are derived from ornamental or landscape plants.  My lab studies the genetic, demographic, and evolutionary processes contributing to plant ‘escape’ from cultivation and successful establishment and spread in natural, managed or urban ecosystems.  Current projects include:

• Inferring the introduction history of horticultural invasives
• Identifying the cultivated sources of invasive populations
• Determining the relative role of sexual versus clonal reproduction in invasive spread
• Assessing the demographic and genetic limitations of small population size
• Elucidating the effects of hybridization between native, introduced, and cultivated species on plant invasiveness