The function of multiple ejaculations in bitterling

0428869 - ÚBO 2015 RIV GB eng J - Článek v odborném periodiku
Smith, Carl - Warren, M. - Rouchet, Romain - Reichard, Martin
The function of multiple ejaculations in bitterling.
Journal of Evolutionary Biology. Roč. 27, č. 9 (2014), s. 1819-1829. ISSN 1010-061X. E-ISSN 1420-9101
Grant CEP: GA ČR GA13-05872S
Institucionální podpora: RVO:68081766
Klíčová slova: Acheilognathinae * alternative mating tactics * fertilization * mating system * sneaking * sperm competition * territoriality
Kód oboru RIV: EG - Zoologie
Impakt faktor: 3.232, rok: 2014

In some taxa, males perform multiple ejaculations, which may function in sperm competition or in maintaining a baseline density of spermatozoa in the female reproductive tract to ensure fertilization, a process that has been termed "topping up". We investigated the function of multiple ejaculations in two species of bitterling, the European bitterling (Rhodeus amarus) and Chinese rose bitterling (Rhodeus ocellatus). Bitterling oviposit in living freshwater mussels, with fertilization taking place within the mussel gill cavity. Thus, although fertilization is external, the mussel is analogous to the female reproductive tract in an internally fertilizing species. We measured the frequency of ejaculations and mussel inspections by individual males of two bitterling species in 28 replicated mesocosms and examined focal male responses to rival ejaculations and the presence of females in spawning condition. We used a model of ejaculatory behaviour to simulate the temporal abundance of spermatozoa in mussels. Male R. amarus exhibited high rates of ejaculation and inspection of the siphons of mussels and increased their ejaculation rate in response to the presence of females in spawning condition. Rhodeus ocellatus showed lower overall rates of ejaculation, but significantly elevated ejaculation rate in response to rival ejaculations. The ejaculatory strategy of R. amarus is one that maintains a minimum level of spermatozoa in mussels, which is elevated when the probability of oviposition increases. In contrast, R. ocellatus engages more directly in sperm competition with rivals. We discuss these results in the context of the function of multiple ejaculations and male mating tactics.
Trvalý link: http://hdl.handle.net/11104/0234105