Does sound matter? The influence of stridulation in competition for carrion resources in burying beetles (Silphidea: Nicrophorus)

Competitive ability in intrasexual contests contributes to differential mating success in many systems. Further, traits that confer advantage in gaining resources associated with survival may also confer an advantage in contests for mates. Thus natural selection can complement and even shape the effects of indirect sexual selection in some mating systems. During contests, individuals assess traits of their opponent to avoid conflicts which may result in energetically expensive fights leading to reduced fitness or death. These traits correlate with quality, and involve displays of armature, accentuation of body size, or acoustic displays that act as a proxy for fitness and signal competitive advantage. Often, body size correlates with competitive advantage and contributes to differential mating success; in general, larger individuals win contests for resources. Sound characteristics often correlate with size and can therefore reveal the competitive ability of an opponent. Nicrophorus burying beetles use sound during contests for carrion breeding resources, but whether acoustic cues act as signals in contests remained to be tested, especially in light of varied body size across populations. Here, we examined the role of sound and body size in resource competitions in N. marginatus, investigating whether stridulation or size influences the outcome or duration of contests. We intrasexually contested like-sized and asymmetrically sized beetles, with and without ablated stridulation, and found that sound does not contribute competitive advantage in any context. Body size, however, is a predictor of contest outcome, and so the question remains as to why Nicrophorus beetles stridulate during contests for resources.