Male-male courtship behaviour, not relatedness, affects the intensity of contest competition in the field cricket

Males often compete intensely against rival males because access to females is a major factor contributing to their reproductive success. However, there is controversy over whether male-male competition is weakened when rival males are related, with reduced aggressiveness leading to inclusive fitness benefits. Furthermore, same-sex sexual behaviour is also expected to mitigate male-male contests. Here, I examined how relatedness, developmental familiarity (i.e. males reared in the same container or not) and same sex sexual behaviour affect the intensity of male-male competition in wild-caught field crickets, Teleogryllus occipitalis. Relatedness and familiarity had no significant effect on the intensity of male-male contest behaviour. However, same-sex sexual behaviour did weaken male-male competition. In conclusion, my results indicate that same-sex sexual behaviour in this cricket has adaptive significance by mitigating risky male-male contest behaviour.