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A Publication on Ants

Louis & Bessie Stein Family Fellowship awardee Sean O’Donnell, PhD, College of Arts & Sciences of 2019 gets published for the data

September 10, 2020

Tell me a bit about your research you did in connection with the Louis & Bessie Stein Family Fellowship (Stein Fellowship) last summer. Who were your collaborators? 

I want to start out giving a background to the work that I usually do. We use social insects as models to see how variation in climate allows animals to handle this varying climate. We measure the ant’s physiology to see if there is a connection between that and the climate variation. We use ants specifically because they are small bodied and typically exposed to this variation. We have been doing this for a few years but usually in the tropics and on mountain sides. I saw the call for proposals for Stein and though it would be interesting to shift this study to the desert climate as well. I saw that Drexel had a relationship with Ben Gurion University of Negev (BGU) and found, with further research, that they have labs and do work in the desert. I looked to work with Itamar Giladi does research with plant stability in the desert, but who had a side project researching ants. There are ants there that harvest seeds, and they are seed predators eating the plants, and this could have an impact on the plant’s abilities to reproduce. I reached out to see if there was an interest of his to work together on the Stein fellowship and research the temperature variation impact on these ants and to see if it impacted the way they affect the plants through this seed predation. We also got some of my students and my research project to go and we got great data. For my studies it was a big ecological and geographical shift and was very interesting – it is a fascinating place to work and I am really hoping to keep this going.




This is the crew hiking in Ein Avdat park, left to right: PhD student Karmi Oxman, Israeli collaborator/host Itamar Giladi, research associate Dr. Susan Bulova, PhD student Virginia Caponera


How did the Stein Fellowship help you accomplish this work? How did you involve students in your work?

The fellowship was critical and provided the support to make this project happen. We had boosts from Itamar and his lab and other folks on the campus in Israel once we were there but it would not have happened overall without Stein. It has been huge for my lab! It has not only lead to this very exciting data set and publication for my lab, but I also got two PhD students and a research assistant to come with me. Everybody on the crew was heavily involved in data entry while we were there, and one of my PhD students who was with me on the trip – Karmi Oxman – is probably going to now end up doing her PhD research in Israel, much of it likely based at the Sede Boker campus where we worked. She will be working on these crazy isopods (crustaceans like our roly-polies) that we collected some data on as a side project, that are social and love in monogamous family groups. We got potential for not only long-term communication between me and Itamar and our labs but also for my PhD student who will get her thesis work started all because of those two weeks in Israel through Stein.

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(Left) PhD students Karmi and Ginny collecting temperature data at an ant colony in the field at Sede Boker. (Right) PI Sean O'Donnell collecting research subjects (Messor arenarius ants) on the Sede Boker campus.


What have been some of the outcomes of your Stein Fellowship? What are your future plans for the research project?

I was really impressed with my students and everyone involved with the project. We collected tons of data, so much so that the editors and reviewers of our publication all commented on how they were all impressed by the size of the data set we collected, especially given the amount of time that we were there collecting it.

I think the data that we collected was also very interesting as an outcome. We collected data of two different ant species that are related to each other (in the same genus) and they co-occur in the desert with their nests intermingled with each other. They also harvest the same resource which is the seeds of the plants that Itamar studies. We are trying to see through the data whether they differ in their thermal physiology and it turns out that they do. The two species differ in their body size ranges, so the workers within each species and colony range very widely in body size. It turns out that the body size variation in the smaller species predicts their thermal physiology quite dramatically. The smaller ones are more sensitive to heat than the large ones. The small ones’ sensitivity to heat suggests that temperature variation could play a role in restricting when these ants can get out and forage for seeds and therefore affect how they compete with each other and partition the resources in the desert.

We are very happy with these findings and that we were able to get them published in a good journal. Longer term goals for Itamar and I are to take that data set and that initial publication and use it to build a larger grant proposal to extend the work.



Nest entrance of the ant Messor ebeninus, one of our research subjects. Note the variation in worker ant body size.


What is something that you would pass along to future Stein Fellowship applicants?

For me what was valuable and important is if you do not have a potential collaborator in mind already – and this was the case for me as I did not know Itamar at all before this collaboration – I think It is important to think carefully about who you might want to work with. I have colleagues in Israel but they all work on systems different enough from mine and so it would not make sense to work together. I would say find someone who has overlap in mutual interests and get in touch with them and try to find common interests. I think that maybe I was lucky but I wish that Itamar and I had met 20 years ago, I think that we could have been friends and collaborators the whole way through. It has turned out to be a fantastic connection for us and for our labs to work together.

I think that this is what the Stein fellowship is all about, you know, it is meant to help people form unexpected or maybe unanticipated new connections. Again, it is not only connecting with this lab but for us it is branching out into a whole new ecosystem and I feel that it is going to open up a whole new line of work for my lab group.

How do you think you will carry your experience and work with the fellowship into your future interests and work?

It depends now on us to be able to get that grant at this point. It looks likely that Carmi will go back for the social isopods so that is already progress and an already directly impactful experience for her to go forward with her interests and work. For Itamar and I, we are really hoping for a grant and to continue collecting data on these ants and I will carry what we collected during Stein forward to achieve this.

Anything else you would like to mention that we did not talk about?

Just speaking on the country itself, there are lots of institutions throughout Israel that would be great for collaboration. The way that the country changes ecologically throughout the country: Jerusalem is Mediterranean, further north even wetter, but the further south it gets hotter and drier. This provides an amazing gradient in a country about the size of NJ that gives so much opportunity for varied research. There are universities and opportunities scattered everywhere, and I was particularly impressed with BGU. The research facilities that they have in the desert are great, I highly recommend.

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This is Ein Avdat national park- adjacent to the BGU Sede Boker campus where we worked. Stunning! (Right) A large male Ibex- these were common around campus.