Ellen Simms, Professor

Closed (1) Do rhizobia adapt to herbicide exposure?

Applications for Spring 2019 are now closed for this project.

Legumes benefit from symbiotic relationships with nitrogen-fixing bacteria called rhizobia, which colonize nodules in legume roots. Chemical herbicides are used to control weeds in both agriculture and horticulture. Rhizobia are exposed to these chemicals when they are used to control weeds in leguminous crops or to control leguminous weeds. The goal of this project is to determine whether rhizobia exposed to herbicides adapt to this stress by evolving the ability to grow in the presence of these chemicals. If we find evidence that rhizobia have adapted to herbicide exposure, we might also test if herbicide adaptation involves a fitness trade-off, i.e., whether rhizobia able to grow in the presence of herbicides grow more slowly in the absence of herbicide.

You will collect rhizobia from legume populations that differ in their history of exposure to herbicides and test these rhizobia for their ability to grow in the presence of one or more herbicides. If you identify rhizobia that differ in their ability to grow in the presence of herbicide, you will then test for a fitness trade-off by comparing their growth rates in the absence of herbicide.

You will be expected to keep meticulous field and laboratory notebooks, attend lab group meetings, and write a project report by the end of the semester.

The project includes a small amount of field research (digging up plants) on campus and in city parks, followed by a large amount of laboratory work (isolating and growing rhizobia).

Day-to-day supervisor for this project: Jannick Van Caughenberghe, Post-Doc

Qualifications: You must have a strong work ethic and an interest in microbiology and ecology. You must be dedicated to learning from and contributing to the project, which involves meticulous laboratory procedures, attention to detail, continuous care of bacteria, and sometimes boring and repetitive protocols, but exciting and rewarding results. Experience with sterile technique and bacterial culturing is a plus, but not required. Applicants with a genuine interest in biology will be favored. We prefer that you be at least a sophomore in a Biological Science major with a minimum GPA of 3.0.

Weekly Hours: 9-11 hrs

Related website: http://www.simmslab.org/

Closed (2) Have invasive rhizobia escaped their bacteriophage enemies?

Closed. This professor is continuing with Fall 2018 apprentices on this project; no new apprentices needed for Spring 2019.

Introduced plants can become invasive when they escape the insect and microbial enemies that control native plant populations. Legumes benefit from symbiotic relationships with nitrogen-fixing bacteria called rhizobia, which colonize nodules in legume roots. We have found that three invasive leguminous plant species (French broom, Spanish broom, and Scotch broom) host rhizobia more closely related to European rhizobia than to California rhizobia, which suggests that European rhizobia may have co-invaded California with their legume hosts.

Invasion theory predicts that invasive species might proliferate in a novel habitat if they have escaped the natural enemies that control their populations in their native range. Bacteriophages (phages, for short) are viruses that attack bacteria and can control bacterial population densities.

In this project, we ask if introduced rhizobia are less often attacked by phages than are native rhizobia. If so, then introduced rhizobia might also enjoy enemy escape.


With guidance and support from the project supervisor, you will participate in experimental design, culturing bacteria, isolating and characterizing bacteriophages, and collecting and analyzing data. Over the course of the semester, you may learn sterile technique, initiation and maintenance of bacterial cultures, phage isolation, DNA extraction and handling, and proper data management techniques.

Day-to-day supervisor for this project: Jannick Van Caughenberghe, Post-Doc

Qualifications: You must have a strong work ethic and an interest in microbiology and ecology. You must be dedicated to learning from and contributing to the project, which involves meticulous laboratory procedures, attention to detail, continuous care of bacteria, and sometimes boring and repetitive protocols, but exciting and rewarding results. Experience with sterile technique and bacterial culturing is a plus, but not required. Applicants with a genuine interest in biology will be favored. We prefer that you be at least a sophomore in a Biological Science major with a minimum GPA of 3.0.

Weekly Hours: 9-11 hrs

Related website: http://www.simmslab.org/

Related website: http://www.simmslab.org
Related website: http://kimberlylapierre.weebly.com/

Closed (4) Genetic mechanisms of flowering time in Ipomoea morning glories

Closed. This professor is continuing with Fall 2018 apprentices on this project; no new apprentices needed for Spring 2019.

The timing of flowering influences which animals are available to transport pollen from one plant to another. Plants vary in flowering time among seasons, but also differ in whether they flower during the day or at night. Morning glories are particularly interesting because each flower lives only about 12 hours and some morning glory species flower in the evening and some species flower in the morning. This project focuses on the genetic mechanisms that determine evening versus morning flowering.

Pollinators differ in what kinds of plant traits they prefer, which affects the natural selection they impose on other plant traits. Later goals of the project might be to determine the genetic mechanisms of some of these other, correlated traits.

With guidance and support from the project supervisors (Professors Ellen Simms and Noah Whiteman), you will grow and maintain plants in the greenhouse, pollinate flowers, collect seeds, propagate seedlings, and collecting and analyzing the resulting data. You will also conduct library research on flowering time in Ipomoea. Over the course of the semester, you will learn proper greenhouse and data management techniques. Finally, you may also learn DNA extraction and handling.


Qualifications: You must be dedicated to the project, which involves meticulous laboratory procedures, attention to detail, continuous care of plants and bacteria, sometimes boring and repetitive protocols, but exciting and rewarding results. We are looking for students who are team players. Ideally, you already love plants.

Weekly Hours: 9-11 hrs
Related website: http://noahwhiteman.org/