Medicago Invasion Project

This project is a collaboration between the Friesen lab at MSU, the Porter lab at Washington State University Vancouver, and the von Wettberg lab at Florida International University with funding from the National Science Foundation.

Our big goal is to understand whether mutualisms become less beneficial in the process of species invasions. This project will test the hypothesized trade-off between partner breadth and mutualism benefit across legume hosts and symbiotic rhizobium genotypes from the native and invasive range for two invasive Medicago species that have colonized North America from Europe.

Aim 1: Compare genetic diversity in native vs. invaded host range mutualists. We will use high marker density genotyping to assess genomic patterns of diversity for hosts, and whole-genome sequencing to assemble and annotate rhizobial pan-genomes.

Aim 2: Assess divergence in mutualism properties between the native & invaded range. We will test hypotheses of reduced specialization, partner choice and mutualism dependence in invaded range mutualists using cross-inoculation trials.

Aim 3 : Test the impact of invasion on symbiont genome dynamics and mutualism. We will simulate symbiont invasions in soil mesocosms to compare experimentally evolved symbionts under contrasting host density and host diversity to test whether divergence in mutualism properties over short time scales mirrors shifts in natural populations.

Aim 4: Identify the molecular underpinnings of mutualism specialization. We will take a transcriptomic approach to nominate host-symbiont pathways mediating specialization, illuminating the underlying trade-off structure.

Accomplishments to date:

  • Huge new Medicago and Ensifer collection!
  • Characterizing symbiont distributions in the invaded range
  • First pass genetic diversity characterization of collection

People Involved:


  • Stephanie Porter
  • Zoie Lopez
  • Josh Faber-Hammond


  • Ellie Siler (PhD student)
  • Emily McLachlan (UG)
  • Chandra Jack (BEACON postdoc)
  • Haley Gmutza (UG)
  • Jordan Priebe (UG)


  • Eric von Wettberg

Previously involved personnel:

  • Melissa Boland (UG)
  • Megan Baxter (UG)
  • James O’Neill (UG)
  • Jimmy Woodward (Tech)
  • Carissa Zielinski (Tech)
  • George Davis (Tech)
  • Melanie Arvelo (UG)
  • Evan Kurtz (UG)
  • Thilani Jacobi (UG)
  • Katie Wozniak (UG)