Project 1 – Flower color variation in Castilleja coccinea

Flowers come in all shapes, sizes, smells and colors. Most of this variation is found between different

plant species, however some species demonstrate high levels of variation among individuals of the same

species, a phenomenon we call intraspecific variation. When this type of variation persists within a

species over time it presents an ever-fascinating question to biologists, driving our understanding of how

plants respond to different selection pressures in their environment and how new plant species form.

Selection for a particular flower by pollinators is often identified as an important driver of floral color

variation; however, the relative contribution of abiotic environmental factors in maintaining floral color

variation is less understood. Pigments that produce vibrant flower colors can have additional functions in

plant vegetative tissue related to mediating environmental stress. Thus, in some cases flower color

variation may be driven by the environment as well as pollinators.

The focal project of this internship seeks to examine the potential influence of environmental agents of

selection in maintaining variation for floral color in Castilleja coccinea (Orobanchaceae), commonly

known as the Indian Paintbrush. Previous range-wide surveys of C. coccinea collections have identified a

distinct flower color variation in this system that is associated with population level differences in soil

moisture and light conditions. To investigate this trend further, we will be studying the physiology and

morphology of this species in response to different light treatments in a common garden setting at the

Chicago Botanic Garden. Typical work tasks include monitoring the experimental plants for changes in

growth, using specialized physiology equipment to measure changes in photosynthesis and processing

plant tissue to measure plant chemical compounds.  

Project 2 – Understanding the role of the pitcher microbiome in physiological function of the carnivorous

pitcher plant Sarracenia purpurea

Carnivorous plants evolved in response to life in nutrient-poor habitats, and they receive the majority of

their nutrients by extracting them from prey using specialized leaves. Prior studies have addressed the

impact of prey capture on physiological function across a range of carnivorous taxa. However, the

obvious interaction between these plants and their prey often overshadows the equally fascinating

relationships they have with non-prey organisms, and there is a surprising lack of research on the impact

of these interactions on the plants’ ability to absorb nutrients and photosynthesize.

The morphology and ecology of the North American purple pitcher plant, Sarracenia purpurea, offer a

unique opportunity for investigating the role of microbial interactions in carnivorous plant success. Like

most pitcher plants, it feeds on insects that become trapped in its pitchers and drown. However, not

everything that enters a pitcher of S. purpurea dies—after initially sterile pitchers open and fill with rain,

they are colonized by a rich community of bacteria and other microbes that feed on trapped insects. Past

studies have largely approached the plant as a vessel for an easily manipulated ecosystem with little

attention paid to the impact microbial diversity has on plant fitness, despite the fact that community

structure is known to play a significant role in nutrient cycling and availability in pitchers and that S.

purpurea is known to be both nitrogen-limited and threatened by excess anthropogenic nitrogen

deposition. This study aims to characterize the diversity of pitcher microbial communities in Sarracenia purpurea across sites and measure the effect of that diversity on the physiological response of S. purpurea

in the presence of organic and inorganic nitrogen.

Throughout these projects, the intern will have the opportunity to learn techniques in genomics, data

collection, and greenhouse maintenance for plant physiology experiments and other aspects of

experimental design and data analysis. Projects will involve field, greenhouse, lab, and computational

work. Depending on the interests of the intern there will be other opportunities to assist with additional

ongoing research projects at the Botanic Garden to develop a diverse skill set related to plant ecology and

evolution research. The intern will also have the ability to participate in various professional development

workshops through the Chicago Botanic Garden during the course of the internship.