New Paper in ‘Functional Ecology’

Response of bluebunch wheatgrass to invasion: differences in competitive ability among invader‐experienced and naïve populations.

Gibson, Nelson & Atwater


I am very excited to have been a part of this publication, in which Alexis Gibson, once a fellow graduate student with me at the University of Montana, investigated evidence of evolutionary responses of bluebuch wheatgrass plants to invasion. Her findings contribute to a growing body of research showcasing the enormous potential for native plants to evolve changes in competitive ability in response to invasion.

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Research Featured in Editorial in Nature

Our recently published paper documenting shifts in the climatic niches of introduced species has been featured in an Editorial published in Nature today. A link to the article can be found here!

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New Paper in ‘Nature: Ecology & Evolution’

Climatic niche shifts are common in introduced plants.

Atwater, Ervine, Barney (link) (pdf)


I am very excited to announce that our paper has just been accepted for publication by Nature: Ecology & Evolution. In it, we show that almost 1000 invasvie plant species occupy much different climates in their introduced range than in their native range.

This finding is significant for several reasons. First, it means that species do not necessarily occupy the same environments everywhere they are found on Earth. Second, it casts doubt on the viability of using information about species’ native-range habitat preferences to predict where they will invade.

However, we found that niche shifts depended upon species growth form, life expectancy, and degree of cultivation, suggesting that ‘niche shifts’ might be predictable.

Particular congratulations go to Carissa Ervine, who contributed to this manuscript as an undergraduate student. She was responsible for assembling the first version of our database of 13 million occurrence records for 1135 species–a major undertaking!

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New Paper in ‘Invasive Plant Science and Management’

Competition and propagule density affect sexual and clonal propagation of a weed.

Atwater, Kim, Tekiela, Barney


This study was pioneered by Wonjae Kim, an undergraduate student at Virginia Tech who designed and executed it on a grant from the Fralin Life Sciences Institute.

Wonjae confirmed that Johnsongrass establishes readily both from seed and from buried rhizome fragments, although these two modes of reproduction differed in their sensitivity to competition and soil quality. In fact, a single plant produces enough seeds and rhizomes to establish over more than a hectare (if spread out evenly)!

Wonjae’s results show that effective management of Johnsongrass must limit spread from both seeds and underground rhizomes.

A great way to ring in the new year!


New Paper in ‘Biological Invasions’

Ecotypic diversity of a dominant grassland species resists exotic invasion

Yang, Callaway, Atwater

In this study, Lixue Yang showed that bluebunch wheatgrass (Pseudorogneria spicata) populations with greater within species diversity were pound-for-pound more resistant to invasion by spotted knapweed (Centaurea stoebe) than populations with less species diversity, by an order of magnitude.

Dr. Yang attributed this to two processes: 1) as seen in our previous study,  more diverse bluebunch populations had greater yield, and 2) even accounting for their increased yield, diverse populations were more resistant to invasion than suspected.

The causes of this phenomenon remain mysterious, but they may have something to do with root recognition among related bluebunch or with activity of soil communities.

This paper takes an important step towards demonstrating the extreme–yet cryptic–effects that within-species diversity has on plant communities.


New Paper in ‘Journal of Plant Ecology’

Evidence for fine-scale habitat specialization in an invasive weed

Atwater, Fletcher, Dickinson, Paterson, Barney (pdf)

In previous studies, we found evidence for striking genetic and phenotypic differentiation in Johnsongrass (Sorghum halepense) populations collected throughout the United States. Here, we report that Johnsongrass may be adapting to local habitat variation.

Johnsongrass from non-agricultural populations competed better in a field community than Johnsongrass from agricultural populations. Agricultural and non-agricultural populations were separated by less than a kilometer, suggesting that this species may be adapting to habitat variation at extremely fine spatial scales.

These results contribute to a growing list of studies revealing the importance of fine-scale habitat specialization in invasive species, with possible ecological and management implications.


New Paper in ‘PLoS One’

Multi-phase US spread and habitat switching of a post-Columbian invasive, Sorghum halepense

Sezen, Barney, Atwater, Pederson, Pederson, Chandler, Cox, Cox, Dotray, Kopec, Smith, Schroeder, Wright, Jiao, Kong, Goff, Auckland, Rainville, Pierce, Compton, Lemke, Philips, Kerr, Mettler, Paterson (pdf)

I’m happy to announce that PLoS One has accepted Uzay Sezen’s paper documenting the population genetics of colonizing Johnsongrass (Sorghum halepense).

Using a panel of almost 500 Johnsongrass accessions from 70 sites throughout the US, Dr. Sezen showed that Johnsongrass was introduced to the US at two locations. It has subsequently colonized much of North America, demonstrating surprising genetic variation even at range margins.

Johnsongrass populations have also differentiated strikingly along habitat boundaries, with genetic clusters segregating strongly between crop populations and those found in roadsides and other disturbed environments.


New Paper in ‘Annual Reviews’

The mechanisms and consequences of interspecific interactions among plants

Aschehoug, Brooker, Atwater, Maron & Callaway (pdf)

I’m very pleased to announce that Annual Reviews of Ecology, Evolution and Systematics has accepted our review article documenting recent advances in our understanding of interspecific plant interactions.

I am proud to have been a part of this group. Erik spearheaded this effort and has worked very hard to bring the finished product together. I look forward to the publication of our review in November!


New Paper in ‘Ecology’

Intraspecific diversity buffers the inhibitory effects of soil biota

Luo, Callaway & Atwater (link)(pdf)


In sterilized soil, bluebunch grew the same regardless of the soil that was used. In unsterilized soil, bluebunch did not grow well in soil from the low-richness plots.

Congratulations to Wenbo Luo for recently having a paper accepted to Ecology! In this paper, Wenbo shows that soil microbes inhibit the growth of related bluebunch wheatgrass plants (Pseudoroegneria spicata).

To do this, he collected soil from bluebunch populations varying in their genetic diversity. He then grew bluebunch seedlings in that soil and compared their growth.

Seedlings did not grow well in soil from populations with low genetic diversity. This effect went away when the soil was sterilized, suggesting that soil microorganisms were responsible.

Soil feedbacks such as these are thought to result from adaptation by soil pathogens. Wenbo’s results suggest that soil pathogens specialize not only on species but on related individuals. This also provides a mechanism affecting the high productivity we see in genetically diverse bluebunch wheatgrass populations.