Size variation, allometry and mating success in Aotearoa|New Zealand kelp flies (Coelopidae)

Abstract The need to respond quickly the presence of an ephemeral resource required for breeding is often a feature scramble competition mating systems. Scramble systems can extreme levels sexual conflict and coercive by males. As result, selection act on various traits used males overcome female resistance behaviours. Selection these may result in significant intra intersexual size variation dimorphism. Additionally, that influence success show positive static allometry. Kelp flies (Coelopidae) are small family Diptera which specialise wrack (beach cast marine macroalgae), highly resource. system involves high conflict, with females rejecting all male attempts. In this study we describe allometry two Aotearoa|New Zealand’s species, Coelopella curvipes Chaetocoelopa littoralis . addition, investigate behaviour C. under ecologically relevant conditions. We found both species evidence dimorphism across measured littoralis, mid tibia length Furthermore, exhibits disproportionally larger males, suggesting trait particular be strong selection. attempt mate significantly more likely successfully demonstrating large-size advantage similar findings Coelopidae. However, only non-significant trend towards longer mid-tibiae. discuss reference population dynamics ecology species.