A study of reproductive ecology of Lake Tanganyikan cichlid fishes as the model systems of cooperative breeding in vertebrates

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In the last year, Drs. S. Awata, K Ota and S Morita conducted field observations. In this year, the cooperative breeding cichlid fish, Julidochromis ornatus is mainly studied. As the studies during the three years, it will be newly confirmed that (1) within a population this fish has most varieties of mating systems, e. g., monogamy, polygyny, classical polyandry, cooperartive polyandry, and polygynandry. This variety will be most in vertebrates, and has been reported from the acorn woodpecker. (2) These variations will be induced by the largest females that can dominate over males. Thus, these females physically control or manipulate males. Thus, not only the sperm competition and a variation of social mating systems, this fish will be good subject animals for the study of female control of paternity, deception, intra- and inter-sexual confficts, reciprocal altruism and mutualism, all being the interesting themes for future research in behavioral ecology. Thus, we are going to make ex … More perimental studied in laboratory using this species during the future 5-10 years.Another cooperative breeding cichlids Chalinochromis brichardi has been studied also in this year. This fish was studied for ca,. 10 years. The mating systems of this fish consist of monogamy, cooperative polyandry and polygynandry. This variation in mating system is smaller than that of J. ornatus partly because that female size was smaller than large alpha males. Thus socially most dominant individuals were males. Thus, dominant order resemble that of the bird dunnock, in which most dominant individuals are alpha males and the cichlid breeding systems also resemble that of the dunnock where cooperative polyandry, monogamy, polygynandry are predominant. Thus, it will be shown that in cichlid fishes of cooperative breeding degree of variations in mating systems are different between species.In Telmatochrmis vittatus, it has been observed that this study population consisted of multiple male reproductively parasitic male-mating tactics: sneaking tactics, satellite-male tactics and pirate male tactics. We hypothesized that sneaker males can evolve to beta males, if they become to conduct paternal care after fertilization, and pirate males can be alpha males, if they target monogamous breeding pair (where pair males to be beta males with parental care). DNA phylogeny analyses may suggest that the genera Telmatochromis, Julidochromis and Chalinochromis will be closely related (but some reports do not support this). If this will be the case, we may say that the alternative male reproductive tactics will have the same root in their origin species. Additionally speaking, the alternative male reproductive tactics in species of these three genera are not genetically determined but changeable according to their growth. Less