Research Interests

General Interests
I am interested in research questions which investigate the morphology, biomechanics, and physiology of animal structures and their movement. I aim to connect these topics to the ecology of these organisms and how this affects how they live in their natural environment. During my Ph.D. work, I have developed a fascination with reptiles, especially chameleons, whose unique specializations provide powerful opportunities to explore the evolution of form and function.

Below are several research projects I am working on, as well as direction that I hope to pursue in the future:


Mechanisms and the evolution of different feeding strategies
Chameleons are well-known for feeding via ballistic tongue projection, which allows them to capture prey items up to 2.5 body lengths away. This mechanism is highly specialized, and requires the functional integration of many different tissue types. Given this degree of specialization, it would seem that this system might not easily be coopted to perform other behaviors. However, several species have been described to feed on certain prey items by directly capturing them using their jaws. My research analyzes the kinematics and associated muscle activation patterns that are used by chameleons feeding by ballistic tongue projection and direct prey capture to identify whether these strategies are constrained to the same kinematic and muscle patterns, or if direct prey capture necessitated the evolution of novel feeding patterns. By comparing multiple species across chameleon genera and closely related agamid species, I am assessing whether these patterns are a reversion back to the ancestral mode of feeding in iguanian lizards.

Effects of temperature on prey choice
As ectotherms, chameleons are strongly influenced by environmental temperature. Their direct prey capture feeding strategy uses muscle powered movement to capture prey. The rate dependent properties of muscle are thermally dependent, meaning their performance is directly related to temperature. As temperature decreases, it takes more time for muscles to perform a task. In contrast, the ballistic projection feeding strategy in chameleons utilizes elastic mechanisms to project the tongue. Previous research has shown that tongue projection in chameleons maintains performance in low temperatures, demonstrating that systems which use elastic mechanisms are less thermally dependent than those powered by muscle alone. I am conducting trials to determine whether these physiological tradeoffs influence behavioral decisions, specifically, whether chameleons prefer to use ballistic projection as temperatures decrease, regardless of prey type. 

Underlying mechanisms and physiology of the tongue and hyoid apparatus
Muscle contraction occurs when sarcomeres shorten; thin actin filaments and thick myosin filaments slide past each other, creating length change and generating force to power movement. However, the movement of these filaments are limited by physical characteristics of the muscle, including z-discs, which act as barriers on either end of the sarcomere. To circumvent limitations imposed by these z-discs, some muscles have evolved supercontraction. Supercontracting muscles have perforated z-discs, which allow the filaments to slide past these barriers, into adjacent sarcomeres, and continue to interact. This modification of the muscle architecture enhances the performance of these muscles, as they can produce force over greater lengths. Previously, there was only one known supercontracting muscle among vertebrates: the m. hyoglossus or retractor muscle in the chameleon tongue. We investigated additional muscles in the tongue and hyoid of the chameleon which also undergo considerable length change, to determine if these muscles also exhibit supercontractile properties, and discovered the second known supercontracting muscle in vertebrates: the m. sternohyoideus superficialis (read more here!).

Morphological variation in reproductive genitalia
I aim to explore the degree of covariance between female and male reproductive morphology and how this covariance changes through phylogeny. It is common in chameleon identification to use male genitalia to differentiate between closely related species. Female reproductive anatomy, however, is far less studied, and little is known about this system in chameleons. Chameleons are additionally a great model system for this study because of their mode of parturition, which varies across the phylogeny. Some species give live birth (viviparity), while others lay eggs (oviparity). This research is critical in understanding the evolution of reproductive mechanisms, and how these traits effect behavior, physiology, and morphology of species.
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Work in Progress: More projects coming soon!​