Study of reproductive ecology and sociality of Lake Tanganyika cichlids : a model system of social evolution of vertebrates

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In this year, Kohda and Takeyarna as a cooperator studied in Lake Tanganyika. Kohda researched breeding ecology of cooperatively polyandrous cichlid Chalinochramis brichardi, especially on the spawning sites in wedge-shaped nests. He found further examples where egg clutches were deposited at the point in the nest to which large alpha males can reach. These were similar to depositing sites observed in previous years. These results may indicate female selectively spawn eggs at the site to which large alpha males can reach, and may lead the hypothesis that through selection of spawning sites by females of this fish, they may control paternity distribution in this fish.In laboratory experiments at the Mpulungu City, female choice of nest shape, wedge-shaped nests and wide nests was examined. AS predidted from field observation in previous years, female tended to choose wedge-shaped nests in which female can control paternity distribution. From field observation of C.brichardi, we obtained … More further examples of egg clutches. Of 11 egg olutches 10 were deposited at the site in nest to which a large alpha male can enter. We made a hypothesis that females can control paternity distribution by selecting such sita as spawning site. Female control of paternity distribution in cooperative breeding vertebrates has been suggested, The test of this hypothesis will be the first example of female control of paternity distribution in extra-fertilizing animals.N.savoryi is known as a haremic cichlid. We found that this fish has helpers, probably related. Cooperative breeding with related helpers has been reported in birds as well as cichlids, but both in birds and cichlids breeding members are of pairs. Thus ; the cooperative breeding of N.savoryi will the first example in haremio mating system. We will examine the relatedness between adults and helpers using samples. We brought ca. 40 individuals of N.savoryi to the laboratory of Osaka City University. Using these live fish, we will conduct aquarium experiment on the cooperative breeding of this fish, Less