Carleton Externs – Sarah’s Final Update

Hello flog, one last time!

Today marks the end of my three weeks here on Team Echinacea, and I’m certainly sad to say goodbye! Nevertheless, it was exciting and rewarding to culminate this externship with a week of data analysis, poster creation, and presentation of findings to the team. While Tris chose to analyze data from Michael’s Echinacea pollen limitation experiment, Julie and I decided to delve into the worlds of Liatris aspera and Solidago speciosa, two other Asteraceae common to prairie ecosystems. Lea has been working with these species for her PhD project over the past few years, studying how timing and location of flowering influences reproductive success, so she was a great help as we commenced our analysis!

After having meticulously cleaned, counted, and classified innumerable Solidago and Liatris flowering heads, Julie and I wondered how the vast differences in head count between these two species may impact each plant’s fecundity (when Liatris plants generally have 10-20 heads, and many Solidago plants have hundreds or even thousands) . Further, knowing that human populations have largely suppressed the occurrence of natural fires in today’s prairies, we were also interested in analyzing the effects of prescribed burns on these common prairie species. We put these two questions together in our data analysis by forming a statistical interaction model–one in which the effect of fire would interact with the effect of flowering head count to influence reproductive success–and fitting it to our Liatris and Solidago data. Interestingly, we did not uncover the same results for these two closely-related plants! For Liatris, the interaction model was highly supported by our data: the head count of plants seemed to have more effect on seed set (a measure of fecundity) in plants that had not been recently burned than in plants that had been recently burned. Yet, for Solidago, this pattern was not present. Our findings suggest that prairie management strategies, of which prescribed burns are an integral part, should carefully consider the species composition of a prairie before burning, because different species may react to burn treatment in different ways. Check out our poster, attached here, for a more detailed analysis, as well as plots of our models!

Before I sign off, I want to send a huge ‘thank you’ to every member of Team Echinacea! This opportunity was incredibly influential for me–this was my first real research experience, and I learned so much about ecology, networking, career paths, data collection, statistics, and more. I had an amazing time, and I hope to see some team members again someday!

Thank you again,


PDF version below:

Soliatris2018 Poster

Carleton Externs Update

Hi Flog!

As we near the halfway point of our externship with Team Echinacea, it’s time for a progress update! Julie, Tris and I have been knee-deep in data collection for the past week and a half: this includes both the “ACE” protocol with Echinacea achenes (cleaning, re-checking, scanning, counting, randomizing to create X-ray samples) and similar processing with Liatris and Solidago specimens. We quickly learned that the pappuses (papi? – the fluffy bits designed for wind dispersal) of Liatris and Solidago achenes adds a new level of difficulty to the counting and randomizing processes. Any air movement–including breaths–can cause major disruption to our work spaces, and the achenes themselves are often frustratingly small.

Though we finally made it through the Liatris samples by the end of last week, with this week commenced the Great Solidago Counting Problem of 2018. With minuscule achenes, of which there may be many hundreds on any given sample, Solidago is not easy to work with–especially when you’d like to estimate achene count per plant. We spent much of our afternoon workshopping several methods of estimation and randomization with Lea and Stuart, hoping to make the process as efficient as possible while also providing reasonably accurate achene counts for Lea to use in her ultimate data analysis. Our final method (still subject to change and optimization) consists of counting the number of heads on each sample, then randomly selecting five heads from which to count achenes. This way, we can extrapolate average achene count per head to the number of heads, then to the number of total florescences of the plant. We hope to power through the remainder of the Solidago samples within the next few days, then begin analysis of all the data we’ve collected!

Until then,


Julie, happy to randomize some Echinacea rather than count Solidago

Carleton College Extern Sarah Allaben

Hello! My name is Sarah Allaben, and I’m a sophomore from Carleton College. I’m excited to be working with Team Echinacea for three weeks as part of Carleton’s winter break externship program. Along with Tris and Julie, I have been cleaning and processing many, many Echinacea angustifolia and Liatris aspera heads in support of projects examining the extent of pollen limitation of Echinacea and the effects of spatial and temporal factors on Liatris and Solidago fitness. However repetitive it may be, I find this process is strangely satisfying (though I do look forward to switching it up a little bit next week and hopefully analyzing some data).

Especially because I’m not quite sure what I’d like to pursue after graduating, this experience is hugely valuable for developing a better understanding of careers in biological research (and receiving advice from accomplished scientists and grad students!). I have yet to delve into too many biology classes, but I’ve found myself most interested so far in paleontology, especially in that it allows for extrapolation of past evolutionary and climatic changes to predict future outcomes of anthropogenic climate change. Yet, after learning more about Carleton’s restored tallgrass prairies, working in the campus greenhouse, and now spending time with Team Echinacea, I’ve developed a strong interest in ecology and plant biology as well! The plan is to gain as much experience in these different fields as I can over the next few years, and see where it takes me. In the meantime, I enjoy rock climbing, art, hiking, and dogs; I’m also a cross country and track runner and love trail running. I’m grateful and excited for the opportunity to work with Team Echinacea, and look forward to my next two weeks here!