Different degrees of lunar synchronization of ovary development between two morphs of a Tanganyikan cichlid fish
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The degree of lunar synchronization of spawning is thought to be related to a strategy that decreases predation on the brood in Tanganyikan substrate-brooding cichlids. Here, I examined the periodic change of ovary development in two morphs of Telmatochromis temporalis: the normal morph uses burrows under stones as spawning nests, whereas the dwarf morph uses holes within empty snail shells. The normal morph showed a significant lunar synchronization of ovary development, but the dwarf morph did not. In the normal morph, spawning prior to the full moon probably decreases the incidence of approaching brood predators and increases the guarding efficiency of parents. In the dwarf morph, however, lunar cyclic spawning may be dispensable, because the spawning nests within shells are probably highly effective for predator avoidance. These two morphs are closely related, and then will be a good model to clarify the widely observed phenomenon of lunar cyclic spawning.
KeywordsCichlidae Gonado-somatic index Lunar cyclic spawning Spawning nest Predator avoidance strategy
I express my sincere thanks to M. Hori for providing facilities for research; to H. Phiri, D. Sinyinza and other staff of the Lake Tanganyika Research Unit in Mpulungu for their full cooperation; to E. Nakajima and D. Sinyinza for comments on the manuscript; to T. Sota, S. Takeyama and K. Ota for advice on research; and F. Tashiro for assistance. This study was carried out in accordance with Guidelines for Animal Experimentation, Kyoto University. This study was supported by Grants-in-Aid for JSPS Fellows (No. 20188), for Special Purposes (No. 18779002) and for Young Scientists (No. 20770065), and Global COE Program (A06), MEXT, Japan.
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