Killer ants in the Peruvian Amazon

Earlier this year, Professor Ray Jayawardhana, Canada Research Chair in Observational Astrophysics, was named the University of Toronto President’s Senior Advisor on Science Engagement and since then, Jayawardhana has been building partnerships with groups in the Greater Toronto Area aimed at promoting outreach by U of T scientists.

“I feel strongly about the value of scientists reaching out and engaging with the wider community, not only to report on our discoveries but also to share the excitement and challenges of the scientific process, to inspire kids and to encourage innovation,” Jayawardhana says.

Among the events organized so far: a series of public talks hosted by the Toronto Public Library. Next up in the series is a talk about ants in the Amazon by Assistant Professor Megan Frederickson, of ecology and evolutionary biology.

U of T News asked Frederickson to provide a glimpse of what her audience can expect from Tales of Cooperation from the Peruvian Rainforest at the Palmerston Public Library Nov. 15. 

What drew you to this area of research?

I have always been interested in understanding why animals, plants, and even microbes cooperate in nature, when evolution is basically selfish (the line "nature, red in tooth and claw" is often used to describe Darwin's theory of evolution). ‘How does cooperation evolve?’ is a fundamental and enduring question in evolutionary biology, and many scientists—myself included—have looked to ants for the answer.

Why ants? Well, ants are some of the most cooperative animals on Earth. Not only do they live in colonies and work together to build a nest, gather food, and raise more ants, they also frequently cooperate with other species—a type of interaction known as mutualism. I have spent the last decade studying mutualisms, including the one between ants and plants in “devil’s gardens,” in order to understand how natural selection can favour the evolution of cooperation, and not conflict, between species. 

What drew you - from Stanford and Harvard - to U of T?

I’m Canadian, but I went to high school in Hong Kong, university in Massachusetts, grad school in California, and then back to Boston for a postdoc—not to mention my many research trips to Peru. After all that time abroad, when I was offered a job at U of T, I jumped at the chance to move back to Canada and to join Canada’s only Department of Ecology and Evolutionary Biology, where so many of my colleagues are internationally renowned scientists.

You mentioned "Devil's Gardens" - can you explain what they are?

Many years ago, a Peruvian friend of mine took me to see a strange clearing in an otherwise pristine Amazonian rainforest. It looked like an orchard, with nothing but one species of tree growing there, in stark contrast to the dense, diverse forest around the clearing. Local people call these places “devil’s gardens,” after an Amazonian legend that tells that they are the work of an evil forest spirit. I was already studying ants at the time, and I noticed that the trees that grow in devil’s gardens are ant-plants, which house ant colonies in their hollow, swollen stems. This made me wonder what role, if any, ants might play in creating devil’s gardens.

So I did a very simple experiment. I got a large number of Spanish cedar saplings from a local nursery that was selling them for reforestation projects. Spanish cedar grows in the forests surrounding devil’s gardens, but never in the gardens themselves as only ant-plants grow there and Spanish cedar is not an ant-plant. I planted the saplings in pairs inside many devil’s gardens and I used a sticky barrier to prevent ants from walking on one plant in each pair. The ants immediately attacked the unprotected saplings, but the plants that I protected from ants survived and grew normally, showing that it is the ants that make these so-called “devil’s gardens.” I also discovered that these ants use formic acid as an herbicide to kill all the plants in devil’s gardens, except the plants they live in.

What is it like to do research in the Peruvian Amazon?

There are few places on Earth where humans haven’t impinged on nature, but some remote parts of the Peruvian Amazon come close. Out on the trails in the conservation areas and national parks where I do research, I’m more likely to have a surprise encounter with a spider monkey or a tapir than with another human being. And at night, there is so little light pollution that the Milky Way looks like a big, bright smear of stars in the sky. Of course, the Amazon Basin is also a hot, humid, muddy place with lots of insects. Personally, I don’t mind the mosquitoes, but I find the sweat bees exasperating because they try to fly up my nostrils and into my ears while I’m collecting data.

There are very few roads in the region, so I get around mostly by boat, which means long, hot days spent making slow progress up rivers. Most Amazonian field stations are “off the grid”; researchers get electricity from solar panels or power generators, or just go without. The cabins have thatch or tin roofs that either leak or make a huge racket when it rains, which is often, and we sleep under mosquito nets that also protect us from spiders, possums, geckos, and other critters. But if I’m reading quietly on the porch, tamarins sometimes jump from nearby trees onto the railings and keep me company for a while.

How do your students adjust/adapt to doing research in a rainforest?

Between teaching field courses and supervising undergraduate and graduate research projects at field sites in Peru, I’ve taken more than 40 U of T students to the Amazon in the last three years. Almost all of them have regarded the experience as the opportunity of a lifetime. I’ve even had several repeat customers, who’ve now been back to Peru two or three times.

You might think that students would get bored, cut off from the rest of the world at a remote field station and without TV or movies for entertainment. But nothing could be further from the truth. They fill their free time by birdwatching, hiking, climbing the 60-meter observation tower to look out over the forest canopy, or searching a swamp to try and catch a glimpse of the anaconda that lives there. One year, my students wrote a whole bunch of jungle-themed songs and entertained us all by singing and playing them on the guitar. There was a very funny one about tracking jaguars.

Your upcoming talk at the TPL is part of Professor Ray Jayawardhana's series of events aimed at engaging the broader public, including youth, in science. How important is science engagement?

Science engagement is very important. The basic science behind environmental issues like biodiversity conservation and climate change is the science of ecology, but most people do not learn much about ecology or biodiversity in school. This is a shame, because biodiversity isn’t found only in the Amazon; there is a lot of biodiversity in and around Toronto, too.

Many people I talk to are surprised to find out that there are even ant-plant mutualisms here. For example, ants disperse the seeds of many Ontario wildflowers, like trilliums and violets. In fact, the flower that appears on Ontario health cards and driver’s licenses depends on ants to disperse its seeds. I have a research project on seed dispersal by ants currently going on at the Koffler Scientific Reserve at Jokers Hill, which is U of T’s biological station and only an hour’s drive from campus.

I hope my upcoming talk will make people see ants in a new light, and maybe even encourage a few people to stop and watch them sometime.