Awardee: Justin Touchon
Semester of Award: Spring 2019
Materials Awarded: Audio equipment (speakers, an amplifier, an equalizer, and speaker cable)
Project Description:
Male frogs produce vocalizations (AKA calls) at night to both attract females for mating and to compete with neighboring males. I have a colony of Neotropical treefrogs at Vassar and we have previously used recording equipment already in the Biology department (by myself and Prof. Megan Gall) to record the calls of male frogs from the colony. With my Fergusson grant, I purchased approximately $1000 of audio equipment (speakers, an amplifier, an equalizer, and speaker cable) which allowed me to play back these recorded frog calls to male and female frogs in order to assess how they compete and make choices about potential mates. The equipment is essential for ensuring that calls reproduced accurately for the auditory system of the species and the projects described below would not have been possible without it.
The first project to use the equipment was my URSI project during summer 2019. Two students participated in the project which had two goals: 1) to assess if female frogs make the same decisions about potential mates when they are faced with two recordings of potential male suitors as compared with the actual males with whom they can interact with, and 2) to measure how males change their calls when in the presence of increasing numbers of competitors. Both of these projects were relatively successful and were presented at the 2019 URSI symposium, including being selected to be one of three URSI projects given time for an oral presentation. For the first project we determined that females do not necessarily make the same choices when faced with real frogs as compared to just the calls of those males, indicating that male behaviors and male-male interactions clearly have the potential to influence female choices. For example, when played calls of two males females showed a clear preference for calls that had higher pulse rates to the call production, but no such preference existed when females chose between two live male frogs. For the second project, we found that male frogs increased their call amplitude and duration (i.e. they made louder and longer calls) when facing increasing competition.
Building on his experience with URSI, one of the students then used the equipment to pursue his senior thesis research in fall 2019 and spring 2020. For his senior thesis, Ben Gregory was interested to know how female decisions about potential mates would be influenced by the presence of ambient anthropogenic noise, such as might be experienced when natural breeding habitats are located near roads. Ben spent countless nights in the basement playing frog calls to competing males and choosy females. His research determined that both the presence of a female and the presence of nearby competitors cause males to call at increasing rates, but these effects are largely masked by background noise. In other words, the presence of noise in the environment seems to make males less able to hear their competitors which causes them to call at a lower rate overall.
The research experiences gained by the students on these projects was invaluable. Both have graduated from Vassar and have been successfully employed in research technician positions, further preparing them for graduate school. We submitted Ben’s thesis work for publication but it was ultimately rejected from the journal we chose. We will revise and submit elsewhere this summer. Similarly, I hope to write up for submission the work from the URSI project this summer.
My lab will continue to make use of the audio equipment purchased with the Fergusson grant. For example, future research will explore how the presence of noise impacts female decisions about mates or the ability of females to discriminate between males that differ in their overall attractiveness. In a similar vein, I would very much like to teach an Intensive which would ask related questions and would teach students various techniques in experimental animal behavior.