2013 Fiscal Year Final Research Report
Latitudinal gradient in sexual selection pressure and reproductive isolation in the genus Oryzias
| Project/Area Number |
23570031
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Ecology/Environment
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| Research Institution | University of the Ryukyus |
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Principal Investigator |
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| Project Period (FY) |
2011 – 2013
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| Keywords | 性淘汰 / 緯度 / 実効性比 / メダカ |
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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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