BEACON Researchers at Work: Mating behavior in treefrogs

This week’s BEACON Researchers at Work blog post is by NC A&T undergraduate Darian Mollock, who worked as an Undergraduate Research Apprentice (URA) at MSU’s Kellogg Biological Station in summer 2014.

getty labMy name is Darian Mollock, I am a junior double major in Lab Animal Science and Animal Science at North Carolina Agricultural and Technical State University. This summer I worked with Michael Kuczynski as an Undergraduate Research Apprentice at the Kellogg Biological Station studying sexual selection and communication in gray treefrogs. The project I worked on was investigating how male calling behavior may change based on an individual’s physical condition and age, and also how female mating preferences and choosiness are influenced by these factors. 

I arrived at the biological station shortly after the beginning of the gray treefrog breeding season. During this time of year, male frogs gather in large choruses where they call to attract females who then choose mates based on certain properties of the calls (length, rate, etc.). Part of our research involved examining female preferences and choosiness in mate selection. In order to assess female mating behavior we had to capture sexually receptive females in the field so we could bring them back to lab for behavioral testing. To ensure that females were sexually responsive we could only collect mated pairs that were already in amplexus (the mating position). Prior to coming to KBS I had never done late night field work in ponds before, so I was excited for my first night to begin. Strapping on my chest waders and head lamp, I headed into the pond to search for the mated pairs. After getting over the initial fear of being in a pond at night not knowing what was lurking in the abyss (I had heard stories of large snapping turtles…), I went in. It was a thrill collecting the gray treefrogs in their natural habitat, and the noise from all of the calling males was deafening. My first night we collected fifty mated pairs – one hundred frogs in total.

photo 3 (1)After we collect the mated pairs we bring the frogs back to the lab and store them in Tupperware containers until the females can be tested. To examine female mate choice we used a series of playback tests that we ran in a small sound chamber. The chamber consisted of a flat tabletop surrounded by sound-dampening blankets with a speaker placed at both ends of the chamber. We would place females in the center of this chamber and observe their response to different frog calls that we could broadcast from the speakers. Specifically, we broadcast attractive (long duration) calls and unattractive (short duration) calls from opposing sides of the chamber. Across multiple trials we would lower the playback volume of the attractive call relative to the unattractive call. A lower playback level would simulate the attractive male calling from farther away making it a more costly choice for the females. We examined whether females would switch their preference and move towards the unattractive call when the attractive call was played at lower volume. We then investigated whether a female’s age, size, or physical condition influenced whether she would switch her preference.

Now that the mating season has come to an end we are in the process of analyzing the data we have collected throughout the summer. With our data we will determine whether larger, better condition females are willing to travel greater perceived distances to reach a more attractive mate than smaller, poor condition females.

The overall ten week internship has been remarkable; I have grasped a vast amount of knowledge about field research hands-on. When you are around someone that is passionate about their research you cannot help but get inspired. I am glad I was able to assist as an undergraduate in Michael’s research project. I have picked up valuable skills during my internship that I will carry with me in my future endeavors.

This entry was posted in BEACON Researchers at Work and tagged , , , , , . Bookmark the permalink.

Comments are closed.