Disentangling the effects of male age and mating history: contrasting effects of mating history on pre-copulatory mating behaviour and paternity success

Many studies ask whether older males are better at acquiring mates. Even so, how age affects reproductive success is still poorly understood because male age and mating history are confounded in most studies: older males usually have more mating experience. To what extent does mating history rather than age explain variation in male mating success? And how do mating history and male age determine paternity when there is also post-copulatory sexual selection? Here we experimentally manipulated the mating history of old and young males in the eastern mosquitofish (Gambusia holbrooki). We then recorded male mating behaviour and share of paternity (1259 offspring from 232 potential sires) when they competed for mates and fertilizations. Old males, and males with no mating experience, spent significantly more time approaching females, and attempting to mate, than did young males and those with greater mating experience. Male age and mating history interacted to affect paternity: old males be...