Young biologists meet Faculty-Led projects

At OTS’ La Selva Biological Station, we were fortunate to work with PhD researchers and perform experiments under their leadership. Over the course of two days, OTS students collected data for two separate projects simultaneously. Two pairs of students presented the results of our studies to the rest of our peers and also professors. From the luck of the draw, I was chosen to present our findings along with another fellow student for the cane toad project.

Dr. John Aho talked to us about something that we normally don’t have much regard for: the importance of parasites to ecosystems and their conservation. Aren’t they invaders that cause harm to their hosts? Well yes, but in our study we actually found that cane toad endurance is not affected by parasite load. In order to get to this result, we needed to catch some toads.

We looked for toads in areas likely exposed to agrochemicals and likely not exposed (or less exposed).  The next morning we ran endurance tests by placing them into a treadmill and recording the time it took for them to become exhausted (stop hopping and slide). Dr. Aho drew blood from the individuals for us to see whether their red blood cells were parasitized. After hours of watching toads and counting over 5,000 blood cells, it was time to analyze our data and put together a presentation.

Originally, we had predicted that toads exposed to agrochemicals were not going to perform as well. It turned out there wasn’t a difference in endurance between the two toad groups, even though the toads exposed to agrochemicals had more parasites in their blood. Furthermore, we found a negative correlation between the proportion of white blood cells and endurance in the toads from the agrochemical site. We can now suggest that cane toads are not being affected much by their parasites, since their immune systems are not putting out soldiers for defense, and even more, the endurance of the two groups was not different.

What does all of this mean? Well first, cane toads are pretty hearty and they can support very drastic conditions and parasites in their blood. Second, and most importantly, parasites have a bad reputation; here we found, in this particular case, that they are not impacting the toads performance as was expected. Perhaps parasites aren’t so bad after all – or at least not for these toads. Besides all the sciency research; in two days, I came to learn more about cane toads than I ever thought I would; so much that I was able to put a presentation together with a fellow student and be confident while presenting. Looking back, I imagine my friends and I, wearing  headlamps, chasing toads, being startled as they urinated just after being caught. I smile at all the cool things we are exposed to here. I have also found a new appreciation for parasites, which is something I never thought possible.
Yocelin Brito Bello
University of Illinois, Champagne-Urbana