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

Abstract

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.