Milkweed Adaptation

Got Milkweed? Research and Teaching About Local Adaptation in Common Milkweed 

Contact: Professor Emily Mohl, 

Monarch caterpillars only eat one kind of plant–milkweed. As monarch butterfly populations are declining and more people are planting milkweed, what is important to understand about this food source?


This project investigates local adaptation in common milkweed, Asclepias syriaca, one of the most important food sources for monarchs. In particular, we ask whether local populations of milkweeds outperform nonlocal populations.  Alternatively, certain populations may outperform other populations everywhere.  Understanding these patterns should help us make better decisions about how to manage and plant milkweed populations.

We are engaging educators and students in a replicated, distributed investigation of local adaptation.  Participating institutions are distributed across the range of common milkweed.

Participants collected seeds from naturally occurring local populations of Asclepias syriaca (common milkweed) in the fall of 2017, and then they established experimental plots with about 20 milkweed plants, some from their local area, and some from distant populations. For the next years, they will measure and record data on milkweed growth and herbivory annually in the spring and fall (and optionally during the summer) to determine whether local populations perform better in general.  Our results should help us predict the impacts of moving milkweed to new locations.

One of the unique aspects of the project is that all participants can access datasets for use in their classes and contribute to publications.

The map below shows the distribution of current participants.


We have also developed a series of lesson plans to motivate the project and support student learning in connection with the Next Generation Science Standards.  They are shared with project participants and available to others on request.

Lesson Theme Activities
1. Monarchs and their Decline Introduction to monarch life cycle and population decline Brainstorming, role playing
2. Monarch Population Decline Debate Multiple hypotheses for population decline Read research article, guided debate
3. Milkweed Milkweed traits and measurements Stations to learn about milkweed, discuss the lab
4. Evolutionary Principles Learn/review evolutionary processes, connect to predictions about milkweed adaptation Guided worksheet with video, vocab review, identify questions/predictions for lab
5. Data Analysis Using data to answer questions/test predictions Data entry, visualize and interpret data
6. Applying Local Adaptation Apply learning: is it risky to plant non-local milkweed? Evaluate risks, scientific argumentation
7. Citizen Science Share arguments and evidence with the community Data jam


We expect to be expanding the project soon to include opportunities for collecting observational data.  Some of our main findings indicate that phenology is important for understanding milkweed adaptation, so we’re developing new protocols so that participants can measure and record the timing of milkweed growth and interactions at sites around the country.  If you’d like to be a part of this project, please contact Professor Mohl!