Social Systems and Sex Allocation among Fishes

通过野外和水族箱实验，研究了冲绳珊瑚礁和伊豆半岛岩礁上几种鱼类的社会/交配系统与性别分配的关系。发现以下关系。1.在一夫一妻制和雄性先熟的海葵鱼类双锯鱼属中，已经进行了保持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。在雌雄同体和先雌后雌的濑鱼中，当失去配偶的雄性相遇时，较小的雄性变回雌性，成为从属。在黄鳍笛鲷（Sufflamen chrysopterus）中，通过雄性去除实验发现了雌性-雄性的性别变化。也发现了较小的，无领土的男性，不知道男性是否会变回女性。在一夫多妻和先雌先孕的濑鱼中，雄性没有变回雌性，可能是因为从属的较小雄性也有机会获得生殖成功.在一夫多妻的虾虎鱼Bathygobius fuscus和雀鲷Dascyllus trimaculatus中，我们没有发现这种雄性领地访问交配系统的性别变化迹象。

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.