Oral Presentations

Rhinoceros Beetle Courtship Dancing Analyzed with DeepLabCut Technology

Author Information

Andrea NewbroughFollow

Presentation Type

Presentation

Faculty Mentor’s Full Name

Doug Emlen

Faculty Mentor’s Department

DBS

Abstract / Artist's Statement

In species with large male weapons (e.g. antlers, horns, claws), female choice has traditionally been considered relatively weak since males establish dominance among themselves, and the best fighters were presumed to be the best mates. In Japanese rhinoceros beetles (Trypoxylus dichotomus), males with long horns win fights over feeding territories visited by females and females were thought to be passive. However, it is now clear that females routinely reject males – even large males with long horns — and males must court females with stridulatory songs and trembling, oscillating dances. Why? We hypothesized that hours of repeated battles might exhaust males, depleting their stored energy reserves, and females may be using courtship to select mating partners based on their body condition. Here we tested whether the trembling dances performed by males could signal body condition to females. We restricted food intake for a subset of males and compared the head-dipping and trembling rates of 40 nutrient-stressed and 40 well-fed males. We observed and filmed male courtships and then used DeepLabCut, an estimation algorithm technology, to analyze the courtship dances. Using multiple markers on both the male’s and female’s body, we were able to determine the displacement of their bodies during dances and calculate the speed of their back-and-forth movements. We found that well-fed males trembled faster than the stressed, food-restricted males. While the Emlen Lab is still determining all of the factors that play a role during a courtship, my study utilizing DeepLabCut paints a clearer picture of the function of the trembling dance. Female insects continue to amaze us with the sophistication of their mate choices, and this study reminds us that it isn’t always all about body or weapon size.

Category

Life Sciences

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Apr 19th, 4:15 PM Apr 19th, 4:30 PM

Rhinoceros Beetle Courtship Dancing Analyzed with DeepLabCut Technology

UC 331

In species with large male weapons (e.g. antlers, horns, claws), female choice has traditionally been considered relatively weak since males establish dominance among themselves, and the best fighters were presumed to be the best mates. In Japanese rhinoceros beetles (Trypoxylus dichotomus), males with long horns win fights over feeding territories visited by females and females were thought to be passive. However, it is now clear that females routinely reject males – even large males with long horns — and males must court females with stridulatory songs and trembling, oscillating dances. Why? We hypothesized that hours of repeated battles might exhaust males, depleting their stored energy reserves, and females may be using courtship to select mating partners based on their body condition. Here we tested whether the trembling dances performed by males could signal body condition to females. We restricted food intake for a subset of males and compared the head-dipping and trembling rates of 40 nutrient-stressed and 40 well-fed males. We observed and filmed male courtships and then used DeepLabCut, an estimation algorithm technology, to analyze the courtship dances. Using multiple markers on both the male’s and female’s body, we were able to determine the displacement of their bodies during dances and calculate the speed of their back-and-forth movements. We found that well-fed males trembled faster than the stressed, food-restricted males. While the Emlen Lab is still determining all of the factors that play a role during a courtship, my study utilizing DeepLabCut paints a clearer picture of the function of the trembling dance. Female insects continue to amaze us with the sophistication of their mate choices, and this study reminds us that it isn’t always all about body or weapon size.