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New Paper in ‘Oecologia’

An exotic invasive plant selects for increased competitive tolerance, but not competitive suppression, in a native grass

Fletcher, Callaway & Atwater (pdf)


At each of four sites, bluebunch from knapweed invaded plots (I) had much better ability to tolerate knapweed than those from uninvaded plots (U). However they were not better at suppressing knapweed.

Many congratulations to Rebecca Fletcher, who just had a paper accepted into Oecologia. Her paper shows that spotted knapweed, an invasive plant, selects for bluebunch wheatgrass plants that are tolerant of knapweed competition, but not for ones that are better at competitively suppressing knapweed.

This is the first direct test of the hypothesis that neighbor suppression does not provide fitness benefits to competing plants. Her finding is important because it challenges long-held notions of what makes a plant a good competitor. Becky performed this research as an undergraduate student at the University of Montana, on a grant she wrote for the Montana Integrative Research Experience for Students (MILES) program.



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New Paper in ‘Weed Research’

Propagule pressure alone cannot always overcome biotic resistance: The role of density-dependent establishment in four invasive species

Barney, Ho & Atwater (link)
I am very pleased to announce that we have just had a paper accepted for publication into Weed Research. This paper documents Master’s Student Matt Ho’s research into the role of propagule pressure in invasion. He found that negative density-dependent germination probability causes diminishing returns for species that broadcast a large number of seeds. His results suggest that site conditions and species interactions play an important role in determining invasion probability even when propagule pressure is intense.


Invasion probability increases as the number of seeds (aka propagule size) increases. When germination is density dependent (solid line), invasion probability increases much more gradually than when it is not (dashed line). This means that site conditions play a very important role in determining invasion probability, even when propagule pressure is high.

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NEPPSC 2016 – Philadelphia

Pictured, left to right: Big Dan, Morgan, Little Dan (top); Jacob and Benjamin Franklin (bottom)

I recently presented the results of my niche modeling work at the 2016 Northeastern Plant Pest and Soils Conference in Philadelphia. I went the the conference along with most of the rest of my postdoc advisor’s (Jacob Barney’s) lab and we had a great time. I met a lot of people, including the First American, Benjamin Franklin, who looked great despite being only a week away from his 310th birthday.

At the conference, I presented the results of our study of climatic niche shifts in introduced species. Jacob and I have found that species experience major niche shifts as they cross continents. This work is in preparation for submission.

Also, congratulations are in order for “Little” Dan Tekiela, who won the Robert D. Sweet Outstanding Graduate Student Award and placed first in the Student Paper Contest. Virginia Tech also won the NEPPSC quiz bowl, besting teams from Cornell, Penn State, UMass, Maine, NC State, and Delaware, as well as the EB-ESA Linnaean Games. Graduate students Morgan Franke and Dan Tekiela both gave excellent presentations of their research.