Male Field Cricket Songs Are Altered After Aggressive Interactions

Jamie E Bunting,Ann V Hedrick

doi:10.3389/fevo.2018.00164

Abstract

To address the hypothesis that male acoustic sexual advertisement signals might be indicators of aggressiveness, in addition to chemical signals, we examined the relationship between levels of aggression/dominance status and acoustic sexual advertisement signals in the field cricket Gryllus integer. Males were paired in aggression trials and recorded the night before and the night after the trial. This allowed us to test whether aggression is inherently linked to song phenotypes, or whether aggressive interactions cause males to alter their songs. We found that dominant (winning) males signaled with higher energy, amplitude and power the night after winning an aggressive encounter, but not before the encounter. Time spent calling and the number of calling bouts were unrelated to aggression, whereas whereas winning males increased their bout lengths after winning, and losing males decreased their bout lengths after losing.

Highlights

Sexual selection theory proposes that the selective sex selects mates because of preferences for particular traits in the selected sex, allowing the traits to spread within a population even when those traits appear maladaptive (Darwin, 1874)
A model containing an interaction between dominance status and pre-trial song energy carried the most weight, with significant effects of pre-trial values and significant interaction, indicating dominant males signaled with higher energy after an aggressive interaction but not before (Figure 5)
We tested two alternative hypotheses for how male acoustic signals were related to aggression: (1) that more aggressive and less aggressive males had intrinsically different signals, or (2) that the signals would change depending upon the result of an aggressive interaction

Summary

Introduction

Sexual selection theory proposes that the selective sex (usually females) selects mates because of preferences for particular traits in the selected sex (usually males), allowing the traits to spread within a population even when those traits appear maladaptive (Darwin, 1874). Getty (2006) theorized that high-quality males do not “handicap” themselves by investing larger amounts of energy into their signals, but rather are more efficient at converting energy into signals, which reduces the cost of producing a large or extravagant signal. Another hypothesis states that it is not the cost of the signal, but rather the potential cost of cheating that keeps these signals honest (Számadó, 2011). Most males are able to produce a high-quality signal indicating, for example, that they are very large, but only large males are able to bear the cost of being challenged by other large males responding to their signals (Számadó, 2011)

Methods

Results

Conclusion