I'm particularly interested in understanding how animals assess and make decisions during critical life-history scenarios. I study this by focusing on assessment of competitiors during contests and assessment in mate choice. To better grasp mechanisms of assessment, I integrate across behavior, biomechanics and physiology.
Contest assessment and resolution
I study how animals assess ability and safely resolve contests, using the mantis shrimp Neogonodactylus bredini, which compete over access to territories in coral rubble. During contests, N. bredini exchange visual displays and high-force strikes using their spring-powered raptorial appendages. These strikes are some of the fastest movements in the animal kingdom, able to crack open snails and dismember crabs. How do competitors use these weapons to resolve contests without killing each other?
I've found that N. bredini resolve body length-matched contests by ritualistically exchanging strikes on each other's tailplates (telsons). Contest winners did not have greater peak strike force than losers; instead, winners struck a greater number of times during contests. By studying both behavior and biomechanics, I showed that N. bredini use their deadly weapons to resolve contests without injury. This work was published in 2015 in Biology Letters. Find out more on the publications page.
Theoretical models of contest resolution describe the rules animals follow to resolve contests. When and how do animals decide to give up? To answer these questions, I've matched N. bredini contest dynamics to theoretical models. I’ve tested these models at both the level of the contest (how long do contests last?) using correlation analysis, and at the level of contest behaviors (how do behaviors themselves progress through contests?) using network analysis-based sequential analysis. I found that mantis shrimp make decisions by assessing both their own ability as well as that of their competitor - a similar "mutual assessment" strategy as red deer. This work was published in 2018 in Proceedings of the Royal Society - B. Find a copy of the paper on the publications page.
Energetics and performance across contexts
I am also interested in how animals achieve variation in performance across the myriad tasks they must complete. I've been investigating this by using high-speed video techniques to test how mantis shrimp vary strike kinematics and energetics across contexts.
I pair competitors in contests, film their sparring strikes at 40,000 frames/second, and use R and a MatLab-based mathematical model to analyze strike kinematics and the energy required to deliver a strike. I also allow individuals to strike prey items (snails) and take the same analysis approach to establish the kinematics and energetics of feeding strikes. This work (in preparation for Journal of Experimental Biology) will help understand how and why animals power movements differenlty across behavioral contexts.
Perception and assessment
Classic models of sexual selection assume that receivers of signals perceive and respond continuously to continuous variation in signal form. However, this may not be the case. In categorical perception, continuous variation is perceived as lying in in discrete categories, and stimuli compared across a category boundary are more easily discriminated than those within a category. Categorical perception of signaling traits may fundamentally alter models of sexual selection. I'm currently working with the Nowicki Lab at Duke to test hypotheses related to categorical perception. In zebra finches, we've found that females show categorical perception of carotenoid-based coloration used in mate choice. These results may necessitate a shift in our current understanding of sexual selection. We are following up on these results by testing the prevalence of categorical perception across stimuli (signaling versus non-signaling stimuli) and sex (males versus females), among other continuing projects.