Elizabeth Mendoza, a PhD student at UC Irvine in the Department of Ecology and Evolutionary Biology, discusses with us her paper “What explains vast differences in jumping power within a clade? Diversity, ecology, and evolution of anuran jumping power”, along with her journey into ecology, her current research interests, and hobbies.

Elizabeth Mendoza. Photo credit: UC Irvine Graduate Division
Elizabeth Mendoza. Photo credit: UC Irvine Graduate Division

What is the background behind your paper?

Some animals can move with exceptional speed by first storing energy into the stretch of tendons (and other stretchy tissues) and then releasing this energy at rates faster than what muscle could do alone. This mechanism works similar to using a bow to launch an arrow. First, energy from our muscles is stored in the deformation of the bow as we draw back on the string. Then, when we release the arrow all of the work stored in the deformations of the bow is released at a faster rate than the rate at which it was generated. The rate at which energy is transformed is power, so by redistributing the energy done by muscles and releasing it at a faster rate, elastic structures essentially “amplify the power”. Several animals use this mechanism for jumping locomotion (and other ballistic movements), and it has been shown that if we accounted for all the muscles that could contribute to these movements they still could not account for the power outputs of these movements. In other words, the power generated by the muscles responsible for the movement does not match the power of the movement. Even more interestingly, studies showed that there was substantial variation in the utilization of this mechanism across organisms and within clades, yet the reasons for this variation remained unknown. Our paper examines this variation across body mass and microhabitat within the anuran (frogs and toads) clade.

What are the big questions still to answer?

Pictured are two Great Plains toads (Anaxyrus cognatus) moving across a dirt road during a rainstorm. Photo credit: Elizabeth Mendoza
Pictured are two Great Plains toads (Anaxyrus cognatus) moving across a dirt road during a rainstorm. Photo credit: Elizabeth Mendoza

I think some really important and interesting big questions that need to be answered are how did these systems evolve? Does evolving these elastic mechanisms result in an adaptive radiation, or are elastic mechanisms key innovations? Many studies have come out in the past 30 years that have shown evidence that this mechanism is quite ubiquitous. Additionally, more robust evolutionary trees and comparative analyses are becoming available that will allow us to answer these and other evolutionary questions.  

About the Author

How did you get involved in ecology?

Searching for Cope’s gray tree frogs (Hyla chrysoscelis) at Teal Ridge Wetland in Stillwater, OK. Photo credit: Dalton Hanson
Searching for Cope’s gray tree frogs (Hyla chrysoscelis) at Teal Ridge Wetland in Stillwater, OK. Photo credit: Dalton Hanson

During my last year of undergraduate school at UC Riverside I met the Higham lab while taking a course on the functional anatomy of vertebrates. I learned that they studied the biomechanics of animal locomotion in a lab and field setting and I was very curious to try it out. Dr. Tim Higham invited me to join in on a fieldwork expedition with his then graduate student, Dr. Clint Collins, and collaborator Dr. Rulon Clark and his lab. We spent a month in a remote town called Rodeo, New Mexico studying predator-prey interactions between rattlesnakes and kangaroo rats in the wild. I remember being mesmerized after seeing my first in person rattlesnake-kangaroo rat interaction. This field experience was so transformative for me. It really cemented the idea of pursuing graduate school and trying to merge my interests in biomechanics and ecology.

What are you currently working on?

My current work focuses more on the mechanistic side of elastic energy storage and how these systems respond to perturbations. In particular, my work focuses on resolving the prediction that elastically powered movements shouldn’t be affected by changing temperatures with the observation that frog jump performance does change with temperature, even though we know they use elastic mechanisms. I use bullfrog (Rana catesbeiana) muscles to understand how temperature affects their ability to store and release energy during a jump. I find this project really exciting because it’s helping us understand what the relative contributions of both muscle and elastic energy are in getting a frog to jump.

What’s your current position?

I’m a second year PhD student in the department of Ecology and Evolutionary Biology at the University of California, Irvine and I work under the mentorship of Dr. Emanuel Azizi.

What do you do in your spare time?

In my spare time I like to read books that resonate with my life experiences like The House of Broken Angels by Luis Alberto Urrea or Undocumented by Dan-el Padilla Peralta. I also like to stay active. I regularly go on long runs with my dog, or I ride my bike along the coast. I also really love getting out to the desert when I can to look for cool reptiles. During long school breaks I like to go camping with my girl friends.

You can read Elizabeth’s paper here.

Photo: Elizabeth Mendoza. Photo credit: UC Irvine Graduate Division

Photo: Searching for Cope’s gray tree frogs (Hyla chrysoscelis) at Teal Ridge Wetland in Stillwater, OK. Photo credit: Dalton Hanson

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