Does the mating call of the male plainfin midshipman, Porichthys notatus, reflect mate quality?

Abstract

For signals in nature to be honest, they have to provide information about the sender’s body condition, size, or reproductive quality. The plainfin midshipman (Porichthys notatus) is a model for the study of acoustic signals due to their importance in its social and reproductive behavior. In order to test whether larger males produce louder and lower frequency calls, males were recorded at night and subsequently measured. Overall, loudness of the mate call was significantly positively correlated with body size and swim bladder volume. Body size and swim bladder volume were also significantly correlated with frequency of the first five harmonics; however this correlation was positive. Loudness of the second and the third harmonic relative to the first harmonic also increase with body size and tend to be louder than or the same as the fundamental frequency in larger males. Based on preliminary data, the plainfin midshipman does seem to exhibit honest signals that provide information about the sender’s size, especially in regards to amplitude.