Oral Paper

         Symbioses: Plant, Animal, and Microbe Interactions

The effects of plant inbreeding on mutualisms

Presenting Author
Isabela Lima Borges
Description
One of the major concerns for the persistence of small isolated populations is inbreeding depression. When investigated in plants, the severity of inbreeding depression often depends on the environment in which it fitness is assessed. Here, I use the legume Chamaecrista fasciculata to explore how plant inbreeding combines with mutualistic interactions to affect plant fitness. I conducted two generations of experimental crosses to obtain C. fasciculata that differ in their extent of inbreeding, then planted the resulting seeds in a common garden where they were exposed to mutualist soil bacteria (rhizobia) and ants. I assessed how plants at different inbreeding levels interacted with rhizobia by observing root nodules, and did ant and extra-floral nectary surveys to assess plants’ mutualism with bodyguard ants. Throughout the experiment, I measured different plant fitness metrics, including total seed count. I found that plant inbreeding decreased plants’ investment in the mutualism with ants and with rhizobia. Plant fitness also decreased with inbreeding, yet the slope of that decline varied by trait and was different for plants that did or did not interact with rhizobia. Overall, I find that mutualisms are affected by plant inbreeding, and that mutualist presence or absence can change the severity of fitness losses in inbred populations.