Behaviour 2019
Male age and mating experience are highly correlated, but which determines their reproductive success?
Upama Aich, Megan L Head, Timothee Bonnet, Rebecca J Fox, Michael D Jennions. The Australian National University, Canberra, ACT, Australian Capital Territory, Australia

Older males often perform poorly during reproductive behaviour. It is unclear, however, whether such senescence is due to male age itself or the accumulated costs of the higher lifetime mating effort that is usually associated with male age. This begs two questions: Is it male age or their mating history that affects male mating behaviour? And, how does it ultimately affect male paternity success? The answer requires an experimental approach, but few such studies exist. Here, we experimentally manipulate male mating history to tease apart its effects from that of age on mating behaviour, and paternity success in the mosquitofish, Gambusia holbrooki. Intriguingly, we found that older males, and males with lower past mating effort spent significantly more time chasing females and made significantly more mating attempts than younger males and males with higher past mating effort. We also found a complex interaction between male age and mating history that affected their overall paternity success. Our results highlight that the general pattern of male reproductive senescence described in many taxa may often be affected by male mating history, rather than male age itself.