- 秋田大学教育文化学部研究紀要 自然科学 = Memoirs of Faculty of Education and Human Studies, Akita University. Natural sciences (ISSN:24334960)
- vol.73, pp.23-27, 2018-02-23
In the present study, the fluctuations in the sex ratio of the ostracod Vargula hilgendorfii (Müller, 1890) were studied. Specimens of stage-5 juveniles (last instar) were collected from Akita Port every 5 or 7 days and were reared until they reached maturity. The sex of the adults was identified under a stereomicroscope to determine the sex ratio. The sex ratio varied among collection dates, whereas at the beginning of the generation, the sex ratio was 1:1, a female-bias was apparent in the middle of the generation. These fluctuations were also observed in the second generation. This same sex ratio fluctuation was also observed in 2010 and 2011. These results revealed that the sex ratio varied among collection dates and suggested that sex determination is related to some specific environmental factors.