I am looking for up to two students to work on research projects that will combine laboratory and greenhouse experiments to study reproductive biology of morning glories (Ipmomoea purpurea) for the spring and/or summer semester of 2016.
Students will conduct experiments that are part of a larger study examining natural and sexual selection on floral traits in plants. Most flowering plants have hermaphroditic flowers and, as such, can gain fitness through both female (ovules/egg) and male (pollen/sperm) functions. However, empirical studies thus far have mainly focused on how natural selection works through the female functions. As a result, we know relatively little about how pollen (male) success may affect overall fitness of a plant. Our research group uses quantitative genetics, molecular marker techniques as well as field studies to investigate BOTH male and female fitness of morning glories and with a particular focus on what factors may influence success of pollen grains. In previous studies, we have identified an important male trait – pollen size that varies in natural populations of morning glories. Particularly, we found that larger pollen size grains are more successful than smaller pollen grains during pollen competition – a process commonly occurring in nature when both types of pollen are brought to the same stigma by pollinators. We are now designing further studies to dissect whether/which environmental factors may influence the competitive ability of pollen grains. For example, can the relative quantity of large- vs small-pollen grains used in the pollen competition influence the relative success of different pollen sizes? Does the growing conditions, such as moisture or fertilizer, affect the competitiveness of pollen grains that a plant produces? Finally, does the growing conditions of the maternal plant affect who the winner of pollen competition would be?
This project-based course (PBIO4960) will provide useful pre-professional experience for students in plant biology, biology, horticulture, genetics, and related disciplines. Students will work in a team environment, including Dr. Chang and her graduate students.
Students participated in this project will earn research credits through their active participation in the research project. A research paper in scientific journal format is expected at the end of the semester. Grades will be assigned basing on the performance throughout the semester (80%) and the final paper (20%).
I am looking for a student for the spring semester 2016 to work on research project that will use laboratory methods to study pollen dispersal in Geranium maculatum.
G. maculatum is a gynodioecious species, in which female and hermaphrodite plants are present in the species, and G. maculatum populations range from 0-50% female. G. maculatum is primarily outcrossing; that is, a plant must receive pollen from another individual in order to produce seeds, thus pollinator choice and how a pollinator moves through a population is very important for plant fitness. Previous work in the lab has shown that pollinators discriminate against female plants (Van Etten and Chang 2014); female plants receive 50% fewer visits than hermaphrodites. This may have strong effects on the distance that pollen travels in a population. For example, in a population with high female frequency, pollinators may avoid female flowers, only landing on hermaphrodite flowers that are further apart. But in a population with only hermaphrodites, pollinators may land on every flower, thus pollen dispersal distances might be reduced in hermaphrodite-only populations.
In this project, we will quantify the distance that pollen travels in hermaphrodite-only populations vs. populations with both hermaphrodites and females. I have previously collected maternal plants and seeds, as well as mapped the location of every plant, from 10 populations that range from 0-35% female. We will extract DNA and genotype these individuals. Using this genetic data, we will be able to infer if any of these seeds share the same father, and we can then estimate the distance that pollen travels. We will compare the pollen dispersal distances between populations to see if they differ between population types. Finally, we will use this information to assess how pollinator behavior and movement may differ between populations and the role that female plant presence plays in these behavior differences.
This course will provide training that will be useful experience for students in plant biology and genetics. The lab techniques developed in this project will be an important skill for a student interested in continuing on to graduate school or professional programs. The student will work closely with me to learn the techniques, and be a part of the Chang lab, which broadly researches topics in reproductive biology.
The student in this course will earn credit through participating in the research project. At the end of the semester, the student will write a paper in scientific journal format that includes the results from this project. A grade will be assigned based on participation throughout the semester (80%) and the final paper (20%).