| Budget Amount *help |
¥5,330,000 (Direct Cost: ¥4,100,000、Indirect Cost: ¥1,230,000)
Fiscal Year 2013: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2012: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000)
Fiscal Year 2011: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
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| Research Abstract |
The degree of seasonal synchronization in the appearance of mature individuals were compared among latitudinal species/populations from the tropic to the temperate, using the genus Oryzias as a model system. Laboratory rearing experiments revealed that clutch sizes and spawning intervals are larger and longer, respectively, in higher-latitude species/populations than lower-latitude ones. Besides, periodical field collections revealed that mature females and males tend to appear in synchrony within a seasonally-shorter period in higher-latitude species/populations, and therefore, the operational sex ratio tend not to be biased throughout a year, than lower-latitude populations. These results strongly suggest that sexual selection pressures are weaker in higher-latitude species/populations as a result of life-history adaptations to seasonal environments.
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