Social Systems and Sex Allocation among Fishes

为了研究冲绳雪子岛珊瑚礁和伊豆半岛礁石上几种鱼类的社会/交配系统与性别分配之间的关系，进行了实地和水族馆实验。我们发现了以下关系：1。在一夫一妻制和雌雄同体的海葵鱼Amphiprion spp.中，已经进行了饲养2只雌性的实验，但雌性到雄性的性别变化尚未得到证实。实验将继续进行。在雌雄同体的濑鱼Labroides dimidiatus和天使鱼Centropyge ferrugatus中，当失去配偶的雄鱼相遇时，较小的雄鱼会变回雌性，因为它是从属的。在蝶翅鱼中，通过去雄实验，发现了雌-雄的性别变化。还发现了体型更小、没有领地意识的雄性，不知道雄性是否会变回雌性。在一夫多妻和雌雄同体的黑濑鱼、虾虎鱼和金雀鲷中，雄性没有变回雌性，可能是因为隶属的较小的雄性也有机会获得繁殖成功。在一夫多妻的虾虎鱼fuscus Bathygobius和雀鲷Dascyllus trimaculatus中，我们没有发现这种雄性领地访问交配系统中性别变化的迹象。

Field and aquarium experiments were carried out in order to investigate relationships between social/mating systems and sex allocation among several fish species on coral reefs of Sesoko Island, Okinawa and rocky reefs of Izu Peninsula. The following relationships were found.1. In the monogamous and protandrous anemone fishes Amphiprion spp., experiments keeping 2 females have been conducted, but female-to-male sex change has not yet been confirmed. The experiments will be continued.2. In the haremic and protogynous wrase Labroides dimidiatus and angel fish Centropyge ferrugatus, when males that had lost their mates met together, the smaller male changed back to female as it became subordinate.3. in the haremic trigger fish Sufflamen chrysopterus, we found female-tomale sex change by male removal experiments. Smaller, nonterritorial males were also found, and it is unknown whether males change back to females.4. In the polygamous and protogynous wrasse Halichoeres melanurus, goby Plerosicya muscarum and damselfish Dascyllus aruanus, males did not change back to female probably because subordinate smaller males have also opportunities to get reproductive success.5. In the polygamous goby Bathygobius fuscus and damselfish Dascyllus trimaculatus, we found no sign of sex change in such male-territory-visiting mating systems.