A STUDY ON MATING STRATEGY BASED ON KIN DISCRIMINATION AND REPRODUCTIVE PHYSIOLOGY.

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This research is a part of a research plan to clarify conditions and factors for the coexistence of plural males in a reproductive group of Japanese macaques. For this purpose the research was planned based on the idea that the condition for multi-male group is greatly related to the reproductive success of subordinate males in the group The main subject animal group was the Wakasa group of Japanese macaques in a open enclosure in Primate Research institute. The data of mating behavior and blood samples of them were collected during mating season and blood samples were collected after the babies were born for the analysis of DNA.To analyze the factor influencing male fitness, male dominance order as an index of male-male competition was investigated. Degrees of female approach to males during the process of mating were also studied as the index of males attractiveness (female choice). The result in the present study showed that the male reproductive success was strongly related to female choice rather than to male competition. The participation of mating by subordinate males, that is formation of multi-male groups was found to be supported by female choice.The field study in Yaku island was under the process in collecting faeces and data on mating behavior. Possibility of collecting sampler of semen was improved.As the result of physiological study, the level of estrogen was found to be more than 100 mg/m as the condition of male estrous and 300 mg/m as the condition of ejaculation.Annual change of fecundity rate in the groups in Takasakiyama was analyzed to reveal the general tendency of reproductive rate in a population. Females reproductive success were found large ; female with fecundity rate from 0.3 to 0.9 were 70% in the population. Variation of female reproductive success should be also included in the next research plan in the study on reproductive strategy as well as of male reproductive success.