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Vol. 52, 2013
Reproductive behavior of the male rose bitterling Rhodeus ocellatus as influenced by the
operational sex ratio
Cai-Ping
Liao1,2, Dan Yu1, Yi-Yu Chen1
and Huan-Zhang Liu1*
1The
Key Laboratory of Aquatic Biodiversity and Conservation of Chinese
Academy of Sciences, Institute of Hydrobiology, Chinese Academy of
Sciences, Wuhan 430072, China
2University of Chinese Academy of Sciences, Beijing
100039, China
Abstract
Background: Game theory predicts
that as the operational sex ratio (OSR; the ratio of sexually active
males to fertilizable females) increases, reproductive males may adopt
alternative reproductive behaviors. Empirical studies indicated that
alternative behaviors may differ for different species. In the present
study, we investigated the influence of different male-biased OSRs on
male reproductive behaviors shown by a freshwater fish, the rose
bitterling Rhodeus ocellatus.
Results: Six levels of the OSR (1:1, 2:1, 3:1,
5:1, 7:1, and 9:1) were established, and male leading, aggression, and
preoviposition ejaculation behaviors were recorded. Our experiments
showed that at low OSRs, the leading behavior of male rose bitterling
increased with an increasing OSR, reaching a maximum at an OSR of 3:1,
and then decreased as the OSR further increased. In contrast,
aggression and preoviposition ejaculation behavior continually
increased with an increasing OSR. Notably, males possibly lost their
territorial position to other males and became sneakers when facing
more rivals.
Conclusions: These observations
suggest that at lower OSRs, male rose bitterling mainly rely on leading
behavior, while at higher OSRs, they increasingly adopt aggression and
preoviposition ejaculation. Therefore, for the rose bitterling, (1)
decreased leading behavior and (2) increased aggression and
preoviposition ejaculation are two alternative responses in the face of
an increasing OSR, which is a more straightforward strategy for facing
an increased risk of sperm competition than that adopted by its
congener, the European bitterling.
Key words: Game theory; Alternative behaviors;
Male mating behavior; Rose bitterling.
*Correspondence: E-mail: hzliu@ihb.ac.cn
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