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Thu September 13, 2012
Dr. Richard Lankau, University of Georgia – Native and Invasive Plants
In today’s Academic Minute, Dr. Richard Lankau of the University of Georgia reveals how some native plants are responding to an ecological shift caused by invasive species.
Richard Lankau is an assistant professor of plant biology at the University of Georgia where his research is focused on the ecology and evolution of plant and fungal communities. Particularly, Lankau is interested in the interactions between plants and soil microbial communities, especially mycorrhizal fungi, in determining competitive interactions between plants. He holds a Ph.D. from the University of California Davis.
Dr. Richard Lankau – Native and Invasive Plants
Some invasive species can devastate ecosystems, and it is often assumed that native species will not be able to mount a successful defense. Because native species have had no experience with the invaders during their evolution, they never evolved counter-measures to the combat the new species.
Garlic mustard, a familiar invasive plant to many in the Northeast, provides a classic example of this phenomenon. Garlic mustard produces toxic chemicals in its roots that hurt native plants indirectly, by killing the beneficial soil fungi that the native plants use to acquire resources. Since these chemicals are new to North America, native plants had no defense against them when garlic mustard first arrived over 100 years ago. In my research, I wanted to determine whether any native plants have started to evolve resistance to this invader over that time.
To do this, I compared populations of a common native plant, clearweed, that grew in areas that have yet to be invaded by garlic mustard, and in areas that have been invaded to various degrees. As I suspected, native clearweed plants from an area that had never been invaded were the most vulnerable to garlic mustard. However, native clearweed plants collected from areas where garlic mustard was present and producing high amounts of its toxic chemicals were more tolerant of the invader. They were able to tolerate the invader partly by reducing their dependence of the beneficial soil fungi that the invader kills.
Despite our best efforts to remove them, invaders like garlic mustard are probably here to stay. It is encouraging, therefore, to find that native plants may be able to evolve to tolerate the invaders, and eventually integrate them into the larger ecological community. Future research should consider how to promote this process and minimize the damage done while we wait for this evolution to occur.