Invasivore Sean Hoban recently attended the annual meeting of the Botanical Society of America in Boise, Idaho, which featured a session an afternoon session on some recent studies in plant Invasion Biology. Six researchers presented their latest ecological and genetic findings, from the interactive effects of Amur honeysuckle and white-tailed deer to hybridization among multiple species of knapweed. Overall, the studies give us better knowledge of how and why some species invade, as well as how invaders affect the invaded communities. Here, Sean highlights some interesting findings from each presentation.
Erica Case from UC Davis talked about impacts of goatgrass on the fragile serpentine grasslands of California. These unique habitats only make up 1-2% of California land area but have 10% of the total species! Unfortunately these habitats are being invaded, partly due to increasing use of off-road vehicles, which disperse seeds, and gopher activity, which disturbs the soil and opens a place for the introduced seeds to take hold. Erica talked about how species might be lost from certain local habitats due to invaders, but sometimes they persist in other local habitats. This rare persistence prevents their overall extinction. Her research will help understand what factors help natives persist in some locations but not others.
Next, Gina Marchini from Portland State University presented experimental results working on the invasive bunchgrass Brachypodium sylvaticum (slender false brome), which is native to Western Europe but is invading the Northwest United States. Interestingly, the plant receives much less rain in its invasive locations, so Gina’s aim is to determine exactly what factors allow it to tolerate higher this greater dryness. She found, among other results, that invading individuals can maintain their leaf shape better and their cells are also more elastic than the native source populations, allowing them to keep better hydrated during drought. This drought tolerance ability may be partly due to evolution during the invasion process.
Then, Peter Guiden and Jessica Peebles-Spence from Miami University gave a pair of talks on white-tailed deer and Amur honeysuckle. Using 40,0000 hours or radio-tracking data, Peter showed evidence that deer can eat and then transport honeysuckle seeds up to 8 kilometers. He also found that 31% of pellets germinated even after passing through the deer’s digestive system. Thus, invasivore deer could help disperse, intensify and spread the invasion. Jessica was interested on how the native forest will recover if deer and/or honeysuckle were excluded from plots. She found higher species richness in plots where both of thse invaders were excluded, though it took several years for this native plant community to begin to recover.
The last two talks used genetic tools for different uses. Tomáš Závada from University of Massachusetts Boston used genotypes to determine how many introductions occurred of two knapweed species on Nantucket Island, and to identify hybrids. Lastly, Hannah Marx of the University of Idaho used very large genetic datasets and large computational power to determine how different combinations of species can develop into a community. Specifically she was interested to determine whether evolution of traits that help a species escape competition might be an important mechanism that helps invasive species establish.
Throughout the conference there were many other presentations, posters and discussions on various aspects of plant biology. The next Botany conference will be in Edmonton, Canada in July 2015.