Abstract
Horned beetles are emerging models in the study of coevolution between novel morphologies and behavior. In Onthophagus beetles, large males use horns to fight other males in brood tunnels while small males with higher mobility sneak around the large males to gain access to females. Mating tactics have rarely been described in other dung beetle genera. We studied the horned dung beetle Sulcophanaeus velutinus that exhibits two parallel horns on the prothorax and one on the head. We put two males of different horn lengths, but similar mass, in observation chambers and found that the large male with longer horns won access to the female in physical competition. Speed tests in artificial tunnels show that locomotion is impeded in large males, suggesting an advantage in mobility for males with small horns. This work contributes to the limited existing evidence on the function of alternative morphologies in horned dung beetles taxa.
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Acknowledgements
We are grateful to Pablo Allen, Robert J. Knell and anonymous reviewer for helpful comments and suggestions on earlier versions of this manuscript. We also thank Eylen Fuentes for dung delivery, Erick Rockwell access to his pig farm, Félix Salazar for photos, the Monteverde Biological Station for allowing data collection in their property and the Costa Rican National Conservation System for allowing us permission to conduct research in Costa Rica (RESOLUCION SINAC-SE-GASP-PI-R-052-2016).
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All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. The study was conducted according to ethical legislation of the Costa Rican National System of Conservation Areas (permit SINAC-CUS-PI-R-0065-2017).
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Cummings, M., Evans, H.K. & Chaves-Campos, J. Male Horn Dimorphism and its Function in the Neotropical Dung Beetle Sulcophanaeus velutinus. J Insect Behav 31, 471–489 (2018). https://doi.org/10.1007/s10905-018-9693-x
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DOI: https://doi.org/10.1007/s10905-018-9693-x