ヒメダカの性行動展開の順序について〔英文〕

ONO, Yoshiaki and Tatsumi UEMATSU (Kagawa Univ., Taka matsu) Sequence of the mating activities in Oryzias latipes. Jap.J.Ecol. 18,1-10 (1968). The quantitative research on the chain reactions among the behaviour unit patterns recognized during development of the mating behaviour patterns was made as a preliminary step to study both the mechanism and meaning of the chain reactions in Oryzias latipes. One hundred and twenty one full-grown pairs of both sexes were observed. Each experimental material was isolated and feeded sufficiently for 72 hours before the experiment. Then a male and a female of the same body length were introduced simultaneously in the glass aquarium under the condition of controlled light in the dark room and their behaviour patterns observed for 30 minutes were recorded. No bait was given to them during the observation. The results obtained are as follows. 1) Fifty of the 121 pairs observed developed to copulation (M7) and spawning (M8). 2) From the quantitative research on the chain relation among the mating behaviour patterns the sequence of development of the mating behaviour is concluded to be as follows. Approaching (S1)→following (S2)→courting orientation (M1)→head-up I (M2)→courting round dance (M3)→head-up II (M4)→floating-up (M5)→crossing (M6)→copulation (M7)→spawning (M8)→ejaculation (M9)→fertilization (M10). 3) Considering both the degree of development of each mating behaviour pattern and the mean time from the beginning of the observation to the first occurrence of each behaviour pattern, the mating behaviour seems to develop along two following main processes. S2→M1→M3→M5→M6→M7-10 S2→M1→ M5→M6→M7-10 Regarding S_2→M1→M3 as phase I and S2→M1→M5→M6 as Phase II, the above mentioned processes are represented as follows. Phase I→latter part of phase II→copulation Phase II→copulation 4) Phase I has the biological significance of the promotion of the sexual drive of both sexes. 5) The female behaviour patterns, head-up I and II, are regarded as the avoiding behaviour due to insufficient sexual drive. These behaviour patterns result in the repeating of the male courting behaviour. Then the sexual drive of both sexes is promoted and the synchronization of copulation results. 6) There was observed the repeated phase I when the sexual drive of bath sexes was too low to copulate. Phase II occurred frequently when the sexual drive of the male is high, but that of the female is not so high. When the sexual drive of the male is low, the frequency of the occurrence of the mating behaviour is low or zero. In the pair prepared sufficiently to copulate, there are few repeated occurrences of both phases, or phase I is omitted.